EBCS-10.pdf
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Ethiopian Building Code Standard
ELECTRICAL INSTALLATION OF BUILDINGS
Ministry of Works & Urban Development Addis Ababa, Ethiopia
1996
S661 ,,¢o~a
"'q"qy sWpy ~owdoloAoa tmcpn 19. S)Jl0A\.,J0 A.1lsMW
e
I
---~
E;BCS-lO Electrical 1'onallatloDof lIluitdings
Pr()ject toul1tll Mtmbtrs
'rethnfcal Members
Abashawl Woldemariam (ChaiI1mm) Aletnayehu tnzilwt Bekele Mekonnen Negussie Tebedge
Mohammed A
Seifu 8ir~e
Wouhib Kebede t I>eceaSedbefote ~mpletionofthe PrOject.
Editors
Electro Data Processing &, Publishing. Addis Ababa
B~kar (Secretary)
Alemayehut3izawt Admassu Gizaw tarekegn Abay tesfaye Bayou
FOREWORD
The Proclamation to defme the powers and duties of the Central and Regional Executive Organs of the 'Transitional Government of Ethiopia No. 41/1993 empowers the Ministry of Works and Urban Development to prepare the Country's Building Code, issue. Standards for design and construction works, and follow up and supervise the implementation of same.
In exercise of these powers and in discharge of its responsibility, the Ministry is issuing a .series of Building Code Standards of general application. The purpose of these standards is to serve as nationally recognized documents, the application of which is deemed to ensure compliance of buildings with the minimum requirements for design, construction and quality of materials set down by the National Building Code. The major benefits to be gained in applying these .standards are the harmonization of professional practice and the ensuring of appropriate levels of safety, health and economy with due consideration of the objective conditions and needs of the country. As these standards are technical documents which, by their very nature, require periodic updating, revised editions will be issued by the Ministry from time to time as.appropriate. The Ministry welcomes comments and suggestions on all aspect of the Ethiopian Building Code Standards. All feedback received will be carefully reviewed by professional experts in the field of. building construction with a view to possible incorporation of amendments in future editions.
Haile Assegidie Minister Ministry of Works and Urban Development 1995
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I N T ROD U C TI 0 N
This Code Standard for the Electrical Ins tallation of Buildings is part of the Building Code of Ethiopia: .
.
This Code Standard for the Electrical Installation of Buildings is mainly adopted from lEE Regulations for Electrical Installations and Canadian Electrical Code, Part 1, to suit the Ethiopian conditions. Other publications quoted are shown in the respective sections of the Code and the Ethiopian Authority for Standardization maintains registers of a national and international standards. number of, foreign . The Code embraces several aspects of electrical installation work and sets standards and provisions for safe utilization of electricity. The Technical Committee for Code Standards for the Electrical Installation of Buildings comprises of the following Institutions representing balanced interest of all segments of the public concerned with the subject matter: • Ministry of Works & Urban Development (MWUD) • Building Design Enterprise -(BDE) • Ethiopian Electric Light & Power Authority (EELPA) • Addis Ababa University, Faculty of Technology (AAU) • Ethiopian Authority for Standardization (BAS).
'ETHIOPJAN BU,LDING CODESTANDAAD
EBCS-10 ELECTRICAL.IN·STALLATION OF,
BUILDINGS
TAB:LE OF CONTENTS
Section 1 1.1
1.2 .1.)
Section 2 2.1
2.2
SCope And Definitions Scope '. . . . . . . . . . Nonnative references ' ,. Definitions..... . . . . .. . . . . . . . . . . . . . . .' . : . . . . . . . . . . .. • . . .' .' .. Gen~ral
1
1
2
Requirements
Acbninistrative.. . . . . . . . . . . . .' . . . .. . . . . • .. . . . . . . . . • . .' . . .. . . .. 2.1.1 Authority for rules . . ...•...•._• . . . . . •..". . . . . . . . . . , . " 2.1.2 Pennit ' .....•..........•..' _. . . . . . . .. 2.1.3 Application for inspection ......•. " . . . . . . . . ..'. . . . .' . . .. 2.1.4 Posting of permit .... ',_ .' . . . . . . . . . . . . . . . ...' .' .- .... . .' .- •.- •• 2.1.5 Notification re-inspection .....................•.•..... 2.1.6 Plans and specifications. . • . . . . . . . . • . . • . . .. . .. -. •. . . . . .. " 2.1.7 Connection authorization ......•...•....2.1.8 Re-inspeetion -•......•...-•., -...•..-., ..,... 2;L9 Renovation of existing installatiOn 2.1.10 Use of approved equipment . . . • . . . . • . . . . . . . . . . . • . . . . . .. 2.1.11 Deviation or postponement .................•.......... 2.1..12 PO-wers of rejection . . . . . . . . . .. '" . . . . . . . . . . • . .. . . . . . .. 2.1.13 InStallation of electrical equipment . . . .•...-. . • . . • . .' . . . .' • • .. 2.1.14 Damage and interfer""~e . • . • . . . . . . . • . . . ;, . . • . • . . . ~ • . . .. Technical 2.2.1 Conventional symbols . . . . . . . . . . . . . . . . ._. • . . . . . . . . . . . •• 2.2:.2 Co-ordination· -.........•' 2.2.3 Lo-cation and requirement of substation . . . . . . . . . . . . . . . . . ... 2.2.4 Rooms (spaces) required . . . • . . . . . . ~ . . . . . . . . . . . . . . . . . .. 2.2.5 Location and requirements of distribution boards . . . . . . . . . . . " 2.2.6 Location and requirements ofPBXlPAB-X rooms " o"
• • •-
• • • • • • • •-
• • • • • • •-
•••
-• • • •'
• • • • • • • •' .
20'
20
20
20' 20'
20~
21
21
21
21
22
22
22
22
22
2J;
n,
n
23
23
24
24
I;
2.3
Planning and designing ~....... . .-.......................... 2.3:1 General " . . . . . . . . . . . . . . .. 2.3.2 Layout and installation drawing 2.3.3 Design
25
25
25
25
2.4
'. . ,~ . . . . . . .. . . . .. . . . . . . . . . . . . .. Marking of equipment 2.4.1 General.......;.................................. 2.4.2. Workmanship and materials '. . . . .. 2.4.3 Material for anchoring' . . . . . . . . . . . . . .. . . . . . .. . . . . . . . .. ' 2.4.4 Protection of persons and property . " 2:4.5 Maintainability..................................... 2.4.6 Enclosures........................................
26
26
27
27
27
27
28
, Section 3
II
Dluminstion
3.1 3.2 3.3 3.4
Scope ' " Normative references. . . . . . . . . . . .. . . . . .. . . . . . . . . . . . . . . . . . .. Definitions , " Lighting requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. ,...... 3.4.1 Illuminance 3.4.2 Luminance ' ; , '. . . . . . . . . . . . . .. 3.4.3 Glare· ' 3.4.4 Light direction and modelling 3.4.5 Colour rendering
29
29
30
35
35
35
36
36
36
3.5
~ . . . . . . . . . . . . . . .. Emergency lighting requirements 3.5.1 Escapelighting 3.5.2 Safety lighting for particular hazardous workplaces 3.5.3 Standby lighting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..
37
37
37
38
3.6
Lighting requirements for various types of buildings . ,........... 3.6.1 General 3.6.2 Industrial......................................... 3.6.3 Offices ' ', . .. 3.6.4 Hotels and restaurants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 3.6.5 Educational establishments . '" . . . . . . . . . . . . . . . . . . . . . . . . . . ,......... 3.6.6 Hospitals ,
, 38
38
39
39
39
40
40
3.7
Outdoor lighting requirements 3.7.1 Illuminance....................................... 3.7.2 Colour rendering group. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. ,. 3.7.3 Limitation of glare 3.7.4 Lighting of outdoor fixed location work spaces
42
42
42
43
43
Section 4
Conducton
4.1 4.2 4.3 4.4
Scope "'. ". " ' Nonnative references. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. Defmitions , . . . . . . .. Size of conductors 4.4.1 Phase conductors in a.c, Circuits and live conductors in d.c. circuits.. 4.4.2 Neutral conductors ....•......... ' '.
4.5
Ampacity of wires, cables and flexible cords 4.5.1 Conductor operating temperature 4.5.2 ,Cables connected iri parallel 4.5.3 Cables connected to bare conductors or busbars '4.5.4 Voltage drop ~ ~
4.6 4.7 4.8
Flexible cords ' ',' Colour of conductors Maximum permissible temperature
~
:.......... 70
; ~ . .. 70
-: . .70
. . . . . .. 70
',' .. ". 70
'.' . . . . . . . . . . . . . . . . . • . .. 70
; . . . . . . . . . . . . . . . . .. 71
'.. . . . . . . . . . . . . . .. 71
Annex. (preface) Annex A (Nonnative) - Correction factors Annex B (Nonnative) - Type of cable and ampacity
Section 5
74
85
90
Service And Service Equipment
5.i
Scope ' .. ; ' '.' 5.2 Nonnative references 'j' • • • • • • • • • • • • • • • • • • • • • • • • • 5.3 Defmitions ·.......•· 5.4 . General requirements ..............................•. ~ 5.4.1 Number of services permitted 5.4.2 Consumer's installation not to be supplied through another building. . .. 5.4.3 Conductors considered outside ofa building 5.4.4 Other conductors in raceway or cable' 5.4.5 Clearance from building openings ,
5.S
66,
66
67
69
69
69
Service equipment 5.5.1 ' General 5.5.2 Control
,
'
'
;
141
141
141
142
142
143
143 .
144
144
144
l44 . '.. 145
III
5.6 . Wiring methods . . 5.6.1 Underground consumer's service conductors 5.6.2 Overhead consumer's service conductors
148
148
148
5.7
149
149
Section 6
Metering equipment 5.7.1 Connection
,
Circuit Loading and Demand Factor
6.1 Scope 150
6.2 . Nonnative references , 150
6.3 Defmitions................. . . . .. . . . . . . . . . . . . . . . . . . . . . . • . 'ISO
6.4 General............................................... 151
6.4.1 6.4.2 6.4.3 6.4.4 6.5
Services and feeders 6.5.1 6.5.2 6.5.3 6.5.4 6.5.5 6.5.6 6.5.7 6.5.8
Section 7
7.17.2 7.3
IV
Current calculation . . . . . . . . . . . . . . . . . . . . . . . . .. '.' . . . .. . 151
151
Voltage drop .•.......................... : Maximum circuit loading 151
'.' . . . . . . . . . . . . . 151
Use of demand factor 151
Single-family dwellings. . Apartment and similar multi-family buildings "' Schools Hospitals ;
151
, 152
153
153
Hotels, motels, dormitories, and buildings of similar occupancy 154
Other types of occupancy ..•.......................... )55
Branch circuits 155
Feeder demand factors for lifts 155
Earthing, Bonding, and Lightning Protection Part I - Earthing. and Bonding Scope .....................•........' Nonnative references System and circuits earthing 7.3.1 Direct current.systems 7.3.2 Alternating - current systems . . . . . . . .. . . . . . . . . . . . . . . . . . .
157
157
158
158
158
7.4
Location of system earthing connections ~ 7.4.1 D.C. systems 7.4.2 A.C. systems 7.4.3 Isolated systems '.' 7.4.4 Single service supply to two or more buildings or structures 704.5 . Conductors to be earthed 7.4.6 Current over earthing conductor ~
159
159
l59
}·59 160
; 160
160
7~5
Bonding 161
75.1 Non-current carrying metal parts 161
1.5.2 Exposed non-current-carrying metal parts of equipment •....... 161
75.3 Non-metallic wiring systems i61 161
7.5.4 NOll-electrical services 164
7.5.5 Extraneous fixed metalwork
7.6
Method of earthing . . . . . . . . . . . . . . . . . . . . .. , . . . . . . . . . . . . . .. '. 164
7~6.l 7~6.2
7.6.3 7.6,4 7;65 7.6.6 7.7"
Effective earthing .............•......" " Common earthing conductor .....•...................... Common- earthing electrode :Underground service ; Short section of raceway Fixed equipment
Bon-ding methods
73:1
_. . . '.' . . . . . . .. . . . .'. . . . . . . . . . . . .. 166
Clean surface . . . . . . . . . . . . . . . .'. . . . . . . . . . . . . . . . . . . . . . Bonding at service.equipment. , Means of assuring continuity at service equipment ....... Metal armour or tape ofservice cable ' Bonding at other than service equipment ; . . . . . . . . . . . . . . . . . . Loosely jointed metal raceways .•.......................
1.7:2 7.7.3 7.7.4 7;7.5 7.7.6 7.7;7 Bonding jumpers 7Jl
164
164
164
165
165
165
Earthing electrodes
7.8.1 General 7.8.2 Service pipe electrode 7.8.3 Artificial earthing electrodes
:
166.
166
166
167
167
167
167
168
168
168
169
v
. _ - - - _ . " .. , _ . , . - -
7.9
,.,_ . .
Earthing and bonding conductors 7.9.1 7.9.2 7.9.3 7.9.4 . 7.9.5 7.9.6
0
•••••••••
General Installation of system earthing conductors Installation of equipment bonding conductors Earthing conductor size for d.c. circuits Earthing conductor size for .a.c, system Bonding conductor size 0
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• • • • • • • • • • • • • ,
0
0
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7.10 Earthing and bonding conductor connections 7.10.1 7.10.2 7.10.3 7.10.4 7.10.5
Section 7
171
172 173 174
174
174
, 175
Bonding. conductor connection to raceways Earthing conductor connection to water pipe electrodes, Earthing conductor connections to other than water pipe electrodes .. Bonding conductor connection to circuits and equipment .... o' •• Earthing conductor connection to electrodes' ...............•
175 ' 175
175
176
176
Earthing, Bonding and Lightnin~ Protection ' Part Il - pghtning Protection
7.11 Scope ...
178 '. . . . . . . 178
7.12 Nonnative references, 7.13 Definitions . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . J 79'
7.14 Materials . . . . . . " . . . . . . . . . . . . .. " . • . . . . . . . . . . . . . 180
7.14.1 General 180 7.14.2 Galvanic compatibility '," : 180
',' .. 181' 7.14.3 Corrosion protection , 7.14.4 Mechanical protection ..............•................. 181
7.14.5 Use of aluminium ..........•.•. : 181
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7.15 Fonn 7.15.1 7.15.2 7.15:3 7.15.4
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and size . . . . . . . . . . . . . Air termination Conductors Earth termination Minimum dimension 0
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VI
184
.184
185
185
185
' • • • • • • • • • •
7.16 Air termination . . . . . . . . . . . . . . . . . . . . . . . . . . . . " 7.16.1 General " 7.16.2 Support ' " 7.16.3 Metallic projections 7.16.4 Metallic materials, ~ 7.16.5 Structure within zone of protection 7.16.6 Air termination on roof ' 7.16.7 Air termination on reinforced concrete structure . . . . . . .. . . . . . 0
, I
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185
185 185
.185 186 ' 186
186
. 186
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7.17 Down conductor . . . . . . . . . . . . . . . . . . '. . . . . . . . . . . . . .. , . . . . . . ,.:J86
7.17.1 General · 186
'.' .. '......•............ : .' '187
7.17.2 Routing 7.17.3 Recommended number 187
7.17.4 Mechanical protection " .: 187
7.17.5 Corrosive soil ; 187
7.17.6 Extemal routes not available ; 187
~ ; " : 188 7.17.7 Lift shafts 7.17.8 Re-entrant loops 188
'.' 188
7.17.9 Sharp bends 7.17.10 Bonding to prevent side flashing 188
7.17.11 Bonds ; 188
7.17.12 Test points : 189' 7.18 Earth termination 7.18.1 7.18.2 7.18.3 7.18.4
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Termination ........•. '.' .' 190
~ . . . . . 190
Resistance to earth Eart.h electrodes . . . . . . . . . . . . . . . . :.. . . . . . . . . . . . . . .. . . . 190
Connection point ;' 190
7.19 Common earthing
192
:
7.19.1 Common earth potential .; '.' 7.19.2' Common earth bonding
, .. ' ;
192 '
192
7.20 Use of reinforcement for earthing inconcrete Structures .....:....... 193
7.20.1 General 193
7.20.2 Electrical continuity . .. . . . . . . . . . . . . . . . . . . . . . . . . . 193
7.20.3 Prestressed concrete members 193
7.20.4 Precast concrete members 193
7.21 Structural steel framing for lightning protection '. . . . . . . . . . . ',' . . 7.21.1 General ... . . '" . . . . . . . . . . . . . . . . . 7.21.2 Air termination 7.21.3 Connection .................'.......;............... .. " . . . . . . . . . . . . . . . . . . . 7.21.4 Earthing 7.21.5 Interconnection '
194
194
194
194
194
194
Annex (Informative)
Annex A - System design . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . .. . . 219
Annex B - Consultation .. . . . . 220
VII
Section 8
Wiring Methods
-8.1 Scope..... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . 223
8.2 .Normative reference ; ...........•....... 223
8.3, General requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223
8.3.1 Methods of installations 223
8.3.2 Wiring in ducts and plenum chambers ~ . , 224
8.3.3 Underground installations,
224 8.3.4 Conductors in hoistways
225 8;4
Conductors
8.4.1 Types of conductors
8.4.2 Radii of bends in conductors
8.4.3 Conductor joints and splices
8.4.4 Supporting of conductors
8.5
Open wiring . ','
226 226 . . . . . . . . . . . . . . . 226 227 228 "
8.5.1' Open and clipped direct
8.5.2 Spacing of conductors
8.5.3 .Conductor supports
8.5.4 Spacing of supports
'
228
','
228 228 229 229
8.6
Exposed wiring on exterior of buildings and between Building's on the samepremises 8.6.1 Location of conductors , 8.6.2 Clearance of conductors 8.6.3 Power supply conductors
8.7 8.8
Bare bus bars and risers Installation of boxes, cabinets, outlets and terminal fittings 8.8.1 Number of outlets per circuit 8.8.2 Outlet boxes 8.8.3 Conductors in boxes 8.8.4 Terminal fittings
8.9
Cables, conductors .and wiring methods
'
Annex A (Normative): Schedule of methods of installation of cables
Vlll
;
,
229
229
229
229
230
230
230
',' . 231
231
,231 232
233
Section 9
I
Protection'and Control
9.1 Scope ~ . ~ 9.2 Nonnative references 9.3 General requirements 9.3.1 Protective and control devices 9.3.2 Types and ratings of protective and control devices
~
'
2:37
237
237
237
238
9.4
Protective devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238
9.4.1 Overcurrent devices 238
9.4.2 Earth fault protection 239
9.5 9.6 9.7 9.8 9.9
Fuses ' 240
Circuit breakers 240
Control devices . . . . . . . . . . . . . . . . . . . . .'. . . . . . . . . . . . . . . . . . . . . 240
Switches \., 241
241
Protection and control of miscellaneous apparatus
Section 10
Class 1 and Class 2 Circuits
10.1 Scope 10.2 Normative references 10.3 Classification 10.3.1 General 10.3.2 Class! extra-low-voltage power circuits 10.3.3 Class 2 low-energy power circuits 10.3.4 Hazardous location 10.3.5 Circuits to safety control devices 10.3.6 Circuits in communication cables
,
,
10.4 Class 1 circuits . . . . . . . . . . . . . . . . . . . .' . . . . . . . . . . . . . . . . . 10.4;1 Limitation of Class 1 circuits 10.4.2 Methods of installation for Class I circuits 10.4.3 Overcurrent protection of Class 1 circuits 10.4.4 Location of overcurrent devices in Class 1 circuits ., 10.4.5 Class I extra-law-voltage power circuit sources including Transformers . 10.4.6 Conductor material and sizes 1004.7 Insulated conductors for Class 1 wiring .' " ~ 1004.8 Conductors of different circuits in the .same enclosure, cable, or Raceway 1004.9 Mechanical protection of remote-control circuits 1004.10 Class 1 circuits extending aerially beyond a building
245
245
245
245
246
246
246
246
246
247
247
247
247
247
248
248
248
248
249
249
IX
~ .. I
Section 13 Flammable Liquid Dispensing and Service Stations, Garages, Bulk Storage ,.. Plants,Finishing Processes and Aircraft Hangars
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ELECTRICAL INSTALLATION OF BUILDINGS
(2) A single disconnecting means shall be permitted to serve more than one of the functions described in (1) above. (3) A single disconnecting means shall be permitted to serve two or more motors and their associated starting and control equipment grouped on a single branch circuit. (4) Disconnecting means or the means for operating themshall readily be accessible.
11.8
AIR CONDITIONING AND REFRIGERATING EQUIPMENT
11.8.1 General (1) The provisions of Section 11.7 for overload, overheating and control of motors shall apply to electric motor driving air conditioning and refrigerating equipment.
11.8.2 Branch Circuit (l) A room air conditioner shall be considered as a single motor unit in determining its branch circuit requirements when all the following conditions are met:
(a) It is cord-and-attachment plug-connected. (b) Its rating is not more than 40.0A and 230.0V single phase. (c) Total rated-load current is shown on the room air-conditioner nameplate rather than individual motor currents. (d) The rating of the branch-circuit, short-circuit and earth-fault protective device does not exceed the ampacity of the branch-circuit conductors or the rating of the socket outlet, whichever is smaller. (2) The total marked rating of a cord-and-attachment plug-connected room air conditioner shall not exceed 80% of the rating of a branch circuit where no other loads are supplied. (3) The total marked rating ofa cord-and-attachment plug-connected room air conditioner shall not exceed 50% of the rating of a branch circuit where lighting units or other appliances are also supplied.
268
EBCS-10 1995
ETHIOPIAN BUILDING CODE STANDARD
SECTION 11: INSTALLATION OF ELECTRICAL EQUIPMENT
11.8.3 Disconnecting Means (1) An attachment plug and socket outlet are permitted to serve as disconnecting means for a single-phase room air conditioner rated i30.0Y or less if: (a) the manual controls on the room air conditioner are readily accessible and located within 2.0m of the floor; or (b) an approved, manually operable switch is installed in a readily accessible location within sight from the room air conditioner.
11.8.4 Supply Cords (1) Where a flexible cord is used to supply a room air conditioner, the length of such cord shall not exceed 2.0m for a nominal 230.0Y rating.
11.9
STORAGE BATTERIES
11.9.1 Location of Storage Batteries (1) Batteries with exposed live parts shall be kept in a room or an enclosure accessible only to authorized personnel.
11.9.2 Ventilation of Battery Rooms or Areas (1) Storage, battery rooms or areas shall be adequately ventilated. (2) Storage batteries shall not be subjected to ambient temperatures greater than 45°C or less than the freezing point of the electrolyte.
11.9.3 Battery Vents (l) Vented cells shall be equipped with flame arresters.
(2) Sealed cells shall be equipped with pressure-release vents.
11.9.4 Battery Installation (l) Battery trays, racks and other surfaces on which batteries are mounted shall be:
a) level,
b) protected against corrosion from the battery electrolyte,
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ELECTRICAL INSTALLATION OF BUILDINGS
c) covered with an insulating material having a dialectic strength of at least 1500.0V, d) of sufficient strength to carry the weight of the battery, and e) designed to withstand vibration and sway, where appropriate. (2) Battery cells shall be spaced a minimum of 1O.Omm apart. (3) Battery cells having conductive containers shall be installed on non-conductive surfaces. (4) Sealed cells and multi-compartment sealed batteries having conductive containers shall have an insulating support if a voltage is present between the container and earth. (5) Cells and multi-compartment vented stage batteries, with covers sealed to containers of non conductive, heat resistant material, shall not require additional insulating support. (6) Batteries having a nominal voltage greater than 230.0V and with cells in rubber or composition containers shall be sectionalized into groups of 230.0V or less. 11.9.5 Wiring (1) The installation of wiring and equipment in a battery room shall be in accordance with the requirements of a dry location.
(2) The wiring between cells and batteries and between the batteries and other electrical equipment shall be: a) b) c) d)
bare conductors.which shall not be tapped; open wiring; a jacket flexible cord; mineral-insulated cable provided it is adequately protected against corrosion where it may be in direct contact with acid or acid spray; or e) aluminium-sheathed cable provided that it has a suitable corrosion-resistant protection, where necessary. (3) Where wiring is installed in rigid conduit or electrical metallic tubing: a) the conduit or tubing shall be of corrosion-resistant material suitably protected from corrosion; b) the end of the raceway shall be tightly sealed with sealing compound, rubber tape, or other acceptable material, to resist the entrance of electrolyte by spray or creeping;
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c) the conductor shall issue from the raceway through a substantial glazed insulating bushing; d) at least 300.0mm of the conductor shall be free from the raceway where connected to a cell terminal; and e) the raceway exit shall be at least 300.0mm above the highest cell terminal to reduce the electrolyte creepage or spillage entering the raceway. Table 11.1 Minimum temperature rating for the insulation of motor supply conductor [0C] (Based on ambient temperature of 30°C) Insulation class rating. Motor enclosure
A
B
F
H
All except totally enclosed nonventilated
75
75
90
110
Totally enclosed non-ventilated
75
90
11.0
110
Table 11.2 Conductor sizes for motors for different service requirements Percentage of nameplate current rating of motor
s-rnlnute rating
15 minute rating
30-and 60 minute rating
Contlnu ous rating
110
120
150
-
85
85
90
140
Periodic duty Rolls, ore-and coal-handling machines, etc.
85
90
95
140
Varyng duty
110
120
150
200
Classification of service
Short-time dUty Operating valves, raising or lowering. rolls, etc. Intermittent dUty Freight and passenger elevators, tools heads, pumps, drawbridges, turntables, etc.
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ELECTRICAL INSTALLATION OF BUILDINGS
TABLE 11.3 Conductor sizes in the secondaryCircuits of motors
Duty cycles
Carrying capacity of conductors In percent of full-load secondary circuit
5 sec on 75 sec off 10 sec on 70 sec off 15 sec on 75 sec off 15 sec on 45 sec off 15 sec on 30 sec of 15 sec on 15 sec off Continuous Duty
35 45 55 65 75 90 110
Resistor duty classification
Light staring duty Heavy starting duty Extra heavy starting duty Light intermittent duty Medium intermittent duty Heavy intermittent duty Continuous dUty
Table 11.4 Rating or setting of overcurrent devices for the protection of motor branch circuits (Except as permitted in Table 11.5 where 16-A overcurrent protection for motor branch circuit conductors exceeds the values specified in here)
Per cent of full-load current
Tlmedela y fuses
Non tlmedelay
Maximum setting tlme limit type circuit breaker
175
300
250
175
300
250
175 175 150
250 200 150
200 200 150
150
150
150
. Maximum fuse rating
Type of Motor
.
Alternating Current Single-phase all types' Squirrel-cage and synchronous: Full-voltage, resistor and reactor Staring Auto-Transformer starting: Not more than 30.0A More than 30.0A Wound rotor Direct Current
The ratings of fuses for the protection of motor branch circuits as given in Table 11.5 are based upon fuse ratings appearing in the Table above, which also specifies the maximum settings of circuit breakers for the protection of motor branch circuits. (il) Synchronous motors of the low-torque, low-speed type (usually 4S0.0rpm, or lower) such as are used to drive reciprocating compressors, pumps, etc., and which start up unloaded, do not require a fuse rating or circuit breaker setting in excess of 200% of full-load current. (iii) For the use of instantaneous trip (magnetic only) circuit interrupters in motor branch circuits, see 11.7.2.5.
Note;
(i)
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~
Table 11.5 Sizes of conductors, fuse ratings, and circuit breaker settings for motor overload protection and motor circuit overcurrent protection (This Table is based on Table 11.4 and a room temperature of 30°C).
Overcurrent protection maximum allowable rating of fuses and Maximum allowable setting of circuit breakers of the time-limited Type for motor circuits [A]
Overload protection for running protection of motor [A] Full~load
current rating of motor [A]
Minimum allowable ampacity of conductor
Maximum rating of Type 0 Fuses
Maximum setting of overload devices
1 2 3 4 5
1.25 2.50 3.75 5.00· 6.25
1.125 2.25 3.5 4.5 5.6
1.125 2.25 3.75 5.00 6.25
6 7 8
7 8
10
7.50 8.75 10.00 11.25 12.50
7.50 8.75 10.00 11.25 12.50
11 12 13 14 15
13.75 15.00 16.25 17.50 18.75
9
9
I
10 12
Single phase, all types and squirrel cage and synchronous (Full voltage, Resistor and Reactor Starting)
!
Squirrel cage and Synchronous (Autotransformer and Star-Delta Starting)
I . I
d.c. or wound rotor a.c.
Non-time delay Fuses
Timedela y"D" Fuses
Circuit breaker
Non-time .delay fuses
Timedela y"D" fuses
Circuit Breaker
Non-time delay fuses
Time delay "0" fuses
Circuit breaker
15 15 15 15 15
15 15 15 15 15
15 15 15 15 15
15 15 15 ·15 15
15 15 15 15 15
15 15 15 15 15
15 15 15 15 1'5
15 15 15 15 15
15 15 15 15 15
20 25 25 30 30
15 15 15 20 20
15 15 20 20 20
15 15 20 25 25
15 15 15 20 20
15 15 15 15 20
15 15 15 15 15
15 15 15 15 15
15 15 15 15 15
30 40 40 45 45
20 25 25 25 30
30 30 30 30 30
30 30 35 35 40
20 25 25 25 30
20 20 30 30 30
29 20 20 25 25
20 20 20 25 25
15 15 20 20 20
, 1
~
~.
12 15 15 17.5 ~F·5
13.75 15.00 16.25 17.50 18.75
I
~ Table 11.5 Sizes of conductors, fuse ratings, and circuit breaker settings for motor overload protection and motor circuit overcurrent protection (conte'd) (This Table is based on Table 11.4 and a room temperature of 30°C).
Overload protection for running protection of motor [A] Full.load current rating of motor [A]
Minimum allowable ampacltyof conductor
Maximum rating of Type 0 Fuses
Maximum setting of overload devices
Overcurrent protection maximum allowable rating of fuses and Maximum allowable setting of circuit breakers of the tlme-llrnlted Type for motor circuits [A] Single phase, all types and squirrel cage and synchronous (Full voltage, Resistor and Reactor Starting)
Squirrel cage and Synchronous (Autotransformer and Star-Delta Starting)
d.c. or wound rotor a.c.
Non-time delay Fuses
Timedela y"O" Fuses
Circuit breaker
Non-time delay fuses
Timedela y "0" fuses
Circuit Breaker
Non-time delay fuses
Time delay "0" fuses
Circuit breaker
16 17 18 19 20
20.00 21.25 22.50 23.75 25.00
17.5 20 20 20 25
20.00 21.25 22.50 23.75 25.00
50 60 60 60 60
30 30 35 35 35
40 40 40 40 50
40 45 45 50 50
30 30 35 35 35
30 30 30 40 40
25 30 30 30 30
25 30 30 30 30
20 30 30 30 30
22 24 26 28 30
27.5 30.0 32.5 35.0 37.5
25 30 30 35 35
27.5 30.0 32.5 35.0 37.5
60 80 80 90 90
40 45 50 50 60
50 . 60 60 70 70
60 60 70 70 70
40 45 50 50 60
40 40 50 50 60
35 40 40 45 45
35 40 40 45 45
30 30 40 40 40
32 34 36 38 40
40.0 42.5 45.0 47.5 50.0
40 40 45 45 50
40.0 42.5 45.0 47.5 50.0
100 110 110 125 125
60 60 70 70 70
70 70 100 100 100
70 70 80 80 80
60 60 70 70 70
60 60 70 70 70
50 60 60 60 60
50 60 60 60 60
40 50 50 50 60
Table 11.5 Sizes of cond.uCtors, fuse ratings,
and Circuit breaker settings fOI" Iilotor overload protection and motor circuit overcurrent protection
(conte'd)
(This Table is based on Tabie 11.4 lind a room temperature of 30°C). "'-
",
- .
..
..
~.
---"
Overload proteCtion for runnin~ protection of motor [Ai Minimum allowable ampacltyof conductor
f'ull-ioad current rating of motor [AJ
Maximum ratirig of type b Fuses
Maximurn setting of averldad devices ..
Non-time delay Fuses
Tirnedela yiiDil Fuses
Squirrel cage arid Synchronous (Autotransformer and Star-Delta Starting)
Circuit breaker ..
Non-time delay . .. fuses
Tlmedela y"D" fuses
Circuit Breaker
d.c, or wound rotor a.c,
Non-time delay fuses
Time delay liD" fuses
Circuit breaker
50 50 50 60 60
52;5 55.0 57;5 60.0 62.5
125 125 150 150 150
80 80 90 90 90
100 100 100 10Q 125
90 90 100 100 1'00
80 90 90 90 90
70 100 100 100 100
70 70 70 80
eo
70 70 70 80 80
60 60 70 70
52 56 58 60
65.0 67.5 70.0 72.5 75.6
60 60 70 70 70
65.0 61.5 70.0 12.5 75.0
175 175 175 175
2dO
100 100 100 110 110
125 125 125 125 150
11o 110 126 126 125
100 100 100 110 110
100 100 100 100 100
80 90 90 90 90
80 90 90 90 90
70 70 70 100 100
62 64 66 68 70
71.5 80.0 82.5 85.0 87.5
70 10 80 80 80
80.0 82.5 85.0 87.5
200 200 20b 225 225
11o 125 125 125 125
150 150 150 150 175
125 150 150 150 160
110 125 125 125 125
125 125 125 125 125
100 100 100 110 110
100 100 100 110 110
100 100 100 100 100
72 14
90.0 92.5 95.0 91.5 100,cl
80 90 90 90 90
225 225 250 250 25Cl
150 150 150 150 150
115 175 175 175 200
150 150 175 115 115
150 150 150 150 150
125 125 150 150 150
110 125 125 125 125
110 125 125 125 125
100 100 100 100 100
78 80 .~..
Singie phase; all types and squirrel cage arid synchronous (Full voltage, Resistor and Reactor St8:rting)
525 55.0 57.5 60.0 62.5
76 ;;.,;j Vi
O"ercurrerrt protection maximum alloWable rating of fuses and lIIIaxlinum allowable setting of circuit breakers of the time-limited type for motor circuits tAJ .. ..
42 44 46 48 50
54
t-:.!
.
..,
',"-
>.
>
77.5
96.0
92.5 95.0 97.5 100.0
..
~
."'
60
Table 11.5 Sizes of conductors, fuse ratings, and circuit breaker settings for motor overload protection and motor circuit overcurrent protection (conte'd) (This Table is based on Table 11.4 and a room temperature of 30°C). I
Overload protection for running protection of motor [A]
Overcurrent protection maximum allowable rating of fuses and Maximum allowable setting of circuit breakers of the time-limited Type for motor circuits [A]
i
- -
Full-load current rating of motor [A]
Minimum allowable ampacltyof conductor
Maximum rating of Type 0 Fuses
Maximum setting of overload devices
86
88
90
102.5 105.0 107.5 110.0 112.5
90
100
100
100
100
92
94
96
98
100
115.0 117.5 120.0 122.5 125.0
105
110
115
120
125
130
135
140
145
150
82
84
Single phase. all types and squirrel cage and synchronous (FUll voltage, Resistor and Reactor Starting)
Squirrel cage and Synchronous (Autotransformer and Star-Delta Starting)
t--~
d.c. or wound rotor a.c.
--,----
Non-time delay Fuses
limedela y"O" Fuses
102.5 105.0 107.5 110.0 112.5
250 250 300 300 300
110
110
110
110
110
115.0 117.5 120.0 122.5 125.0
131.5 137.5 144.0 150.0 156.5
125
125
125
125
150
162.5 169.0 175.0 181.5 187.5
150
150
150
175
175
Circuit breaker
Non-time delay fuses
limedela y"O" fuses
Circuit Breaker
Non-time delay fuses
lime delay "0" fuses
Circuit breaker
150 150 175 175 175
200 200 200 200 225
175 175 175 200 200
150 150 175 175 175
150 150 150 175 175
125 150 150 150 150
125 150 150 150 150
125 125 125 125 125
300 300 300 300 300
175 175 175 175 175
225 225 225 225 225
200 200 200 200 200
175 175 175 175 175
175 175 175 175 175
150 150 150 150 150
150 150 150 150 150
125 125 125 125 150
131.5 137.5 144.0 150.0 156.5
350 350 350 400 400
200 200 225 225 225
250 250 250 250 250
225 225 250 250 250
200 200 225 225 225
200 200 225 225 250
175 175 175 200 200
175 175 175 200 200
150 150 150 175 175
162.5 169.0 175.0 181.5 187.5
400 450 450 450 450
250 250 250 300 300
300 300 350 350 350
300 300 300 300 300
250 250 250 300 300
250 250 250 250 300
20Q 225 225 225 225
200 225 225 225 225
175 200 200 200 225
~
, ,
Table 11.5 Sizes of conductors, fuse ratings, and circuit breaker settings for motor overload protection and motor circuit overcurrent protection (conte' d) (Ibis Table is based on Table 11.4 and a room temperature of 30"C).
Overcurrent protection maximum allowable rallng of fuses and Maximum allowable setting of circuit breakers of the time-limited Type for motor circuits [A]
Overload protection for running protection of motor [A] FUll-load current rating of motor [A]
Minimum allowable ampaclty of conductor
Fuses
Maximum' setting of overload devices
Maximum rating of Type D
~
-...J
Single phase, all types and squirrel cage and synchronous (Full voltage, Resistor and Reactor Starting)
Squirrel cage and Synchronous (Autotransformer and Star-Delta Starting)
d.c. or wound rotor a.c.
Non-time delay F!Jses
limedela y liD" Fuses
Circuit breaker
Non-time delay fuses
limedela y''O" fuses
Circuit Breaker
Non-time delay fuses
lime delay "0" fuses
Circuit breaker
155 160 165 170 175
194 200 206 213 219
175 175 200 200 200
194 200 206 213 219
500 500 500 500 600
300 300 300 300 350
350 400 400 400 400
350 350 350 350 350
300 300 300 300 350
300 300 300 300 350
250 250 250 300 300
250 250 250 300 300
225 ' 225 225 250 250
180 185 190 195 200
225 231 238 244 250
200 200 225 225 225
225 231 238 244 250
600 600 600 600 600
350 350 350 350 350
400 400 400 400 500
400 400 400 400 400
350 350 350 350 350
350 350 350 350 400
300 300 300 300 300
300 300 300 300 300
250 ' 250 250 250 300
210 220 230 240 250
263 275 288 300 313
250 250 250 250 300
263 275 288 300 313
-
400 400 450 450 450
500 500 500 600 600
450 450 500 500 500
400 400 450 450 450
400 400 400 400 500
350 350 350 400 400
350 350 350 400 400
300 300 300 350 350
-
,
Table U.5 Sizes of conductors, fuse ratings, and circuit breaker settings for motor overload protection and motor circuit overcurrent protection (conte'd) (This Table is based on Table 11.4 and a room temperature of 30pe).
Overload protection for r'unnlrtg protection of motor [A] FuJl~load
current rating of motdr [A]
Minimum allowable ampaclty of. col1ductdr ".
Maximum rating of fypeD Fuses
260 270 280' 290 300
325 338 350 363 315-.
300 300 300 350 350
320 340 360 380 400
400 425 450 475 500
420 440 460 480 500
Maximum setting of overload devices
32$ 338'
Overcurtent protectlort maximum allowable rating of f~ and Maximum allowable setting of circuit breakers of the time-limited Type for motor circuits [A] . Single phase, all types and squirrel cage and synchronous (Full voltage, Resistor and Reactor Starting)
Squirrel eage and Synchronous (Autotransformer and Star-Delta starting)
Non-time delay Fuses
Tlmedela
-
500 500 500
600
600
600
600
600
-
y"O. Fuses
Non-time
Tmedela
de18y
y"O.
fuses
fuses
600,
600
600
600
500 500 500 600 600
Circuit breaker
350 363 375
· ·
60Q
600
600
350 400 400 450· 450
400 425 450 475
·
.-
-
-
52.5
500
525
550
500 500 500 600
550
515
600 625
500
575 600
625
-
-
-
~
.
-
-
-
.
· ·-
-
~
-
-
.
-
·
-
· -
-
·
--
500
500 500 500 600
--
.
-
Circuit Breaker
-' ~
d.c. or wound rotor a.c,
Non~time
delay fUSes
Time delay. "0" fuses
400 450 450 450 450
400 450 450 450 450
500 600
500
-
-
600 600 600
-
-
-
-
-
..
-
.
-
Cireuit breaker
350 ~oo
'400 400 400 400 500
600 600 600
500 500
600
600
-
-
. .
-
-
-
SECfION
12
HAZARDOUS LOCATIONS
12.1
SCOPE
(1) This Section applies to hazardous locations in which electrical equipment and wiring are subject to the conditions classified as follows: (a) (b) (c)
12.2
Class I locations in which flammable gases or vapouls are or may be present in the air in quantities sufficient to produce explosive or ignitible mixtures; Class II location which are hazardous because of-the presence of combustible or electrically conductive dusts; and Class III locations which are hazardous because of the presence of easily ignitible fibres or flyings, but in which such fibres or flyings are not likely to be in suspension in the air in quantities sufficient to produce ignitible mixtures.
NORMATIVE REFERENCE
(1) The following reference contains provisions which, through reference in this text, constitute provisions of the Ethiopian Building Code Standard on Electrical Installation of Buildings. (a)
12.3
C22.1:1990
Canadian Electrical Code, Part 1, Safety Standard for Electrical Installations, Sixteenth Edition.
CLASSIFICATION
12.3.1 Division of Class I Locations (1) Class I locations shall be divided into two divisions as follows: (a) Division 1, comprising Class I locations in which:
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.i)
hazardous concentration of flammable gases or vapours may exist continuously, intermittently, or periodically under normal operating conditions; ii) hazardous concentrations of flammable gases or vapours may exist frequently because of repair or maintenance operation or because of leakage; or iii) equipment is operated or processes are carried on, of such a nature that breakdown or faulty operation thereof could result in the release of hazardous concentrations of flammable gases or vapours and simultaneous failure of electrical equipment.
(b)
Division 2, comprising Class I locations in which: (i) flammable volatile liquids, flammable gases or vapours are handled, processed, or used, but in which the liquids, gases, or vapours are normally confined within closed containers or closed systems from which they can escape only as a result of accidental rapture or breakdown of the containers or systems or the abnormal operation of the equipment by which the liquids or gases are handled, processed, or used; or (ii) hazardous concentration of gasses or vapours are normally prevented by . positive mechanical ventilation, but which may become hazardous as the result of failure or abnormal operation of the ventilating equipment; or (iii) the location is adjacent to a Class I, Division 1 location, from which a hazardous concentration of gasses or vapours could be communicated, unless such communication is prevented by adequate positive-pressure' ventilation from a source of clean air, and effective safeguards against ventilation failure are provided.
12.3.2 Division of Class II Locations
(L) Class II locations shall be divided into two divisions as follows: a) Division 1 comprising Class II locations in which: i) combustible dust is or may be ih suspension in air continuously, intermittently, or periodically under normal oeperating conditions in quantities sufficient to produce explosive or ignitible mixtures; ii) jhe normal or abnormal operation or the failure of equipment or apparatus might cause explosive or ignitible mixtures to be produced in, or in dangerous proximity to, 'electrical equipment or apparatus; or
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SECTION 12: HAZARDOUS LOCATIONS
iii dusts having the property of conducting electricity may be present. b) Division 2, comprising Class.II locations in which combustible dusts are not normally in suspension in air or likely to be thrown into suspension by the normal or abnormal operation or the failure of equipment or apparatus in quantities sufficient to produce explosive or ignitible mixtures, but in which: . i) deposits or accumulations of dust may be sufficient to interfere with the safe dissipation of heat from electrical equipment or apparatus; or ii) deposits or accumulations of dust on, in or near electrical equipment may be ignited by arcs, sparks, or burning material from the electrical·equipment. 12.3.3 Division of Class III Locations (1) Class III locations shall be divided into two divisions as follows: a) Division 1, comprising Class III locations in which readily ignitible fibres or materials producing combustible flyings are handled, manufactured, or used .... b) .Division 2, comprising Class III locations in which readily ignitible fibres other than those in process of manufacture are stored or handled. 12.4
GENERAL
REQUI~MENTS
12.4.1 Electrical Equipment (1) Where electrical equipment is required by this Section to be approved for the class of location, it shall also be approved for the specific gas, vapour, or dust that will be present. (2) Such approval in (1) may be indicated by one or more of the following atmospheric group designations which have been established for the purpose of testing and approval: a) Group A, comprising atmospheres containing acetylene; b) Group B, comprising atmospheres containing butadiene, ethylene oxide, hydrogen (or gasses or vapours equivalJnt in hazard to hydrogen, such as manufactured gas), or propylene oxide;
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c) Group C, comprising atmospheres containing acetaldehyde, cyclopropane, diethyl . ether, ethylene, or unsymmetrical dimenthyl hydrazine (UDMH), or other gases or vapours of equivalent hazard; d) Group D, comprising atmospheres containing acetone, acrylonitrile, alcohol, ammonia, benzine, benzol, ethylene dichloride, gasoline, hexane, isoprene, lacquer solvent vapours, naphtha,natural gas, propane, propylene styrene, vinyl acetate, vinyl chloride, xylenes, or other gases or vapours or equivalent hazard; e) Group E, comprising atmospheres containing metal dust, including aluminum, magnesium, and their commercial alloys, and other metals of similarly hazardous character istics; t) Group F, comprising atmospheres containing carbon black, coal or coke dust; g) Group G, comprising atmospheres contaiiring flour, starch or grain dust, and other dusts of similarly hazardous characteristics. 12.4.2 Marking (1) Electrical. equipment approved for use in hazardous locations shall be marked to indicate the class and for Classes I andll locations the group, or the specific gas, vapour or dust for which the equipment has been approved.
(2) Electrical equipment approved for use in Class I hazardous locations may be marked with: a) the maximum external temperature, or b) one of the following temperature codes in Table 12.1 to indicate .the maximum external temperature; Table 12.1 Temperature codes to lndlcsbe the maximum external temperature Temperature code
r.mperature Gode
Max. external temperature [0C]
T1
450
T3A
180
T2
300
T3B
165
T2A
280
T3C
160
T2B
260
T4
135
T2C
230
T4A
120
T2D
215
T5
100
T3
200
T6
85
282 I
Max. external temperature [0C]
EBCS-10 1995
. ETHIOPIAN BUILDING CODE STANDARD
-,
SECTION 12: HAZARDOUS LOCATIONS 'j
(3) If no maximum external temperature marking is shown on Class I equipment approved for the class and group, the equipment, if of the heat-producing type (which excludes junction boxes, conduit fittings, etc), shall be considered as having the following maximum external temperature: Group Group Group Group
A B C D
-
2800C 2800C 1600C 215°C
(4) Equipment approved for Class I, Division 2 only shall be so marked. (5) Electrical equipment approved for operation at ambient temperatures exceeding 400C shall, in addition to the marking specified in 12.4.2 be marked with,the maximum ambient temperature for which the equipment is approved, and the maximum external temperature of the equipment as referred to in (2) and (3) above. 12.4.3 Non-Essential Electrical Equipment (1) No electrical equipment shall be used in a hazardous location unless it is essential to the processes being carried on therein. . (2) Service equipment, panelboards, switchboards, and similar electrical equipment, shall, 'where practicable, be located in rooms or sections of the, building in which hazardous conditions do not exist. 12.4.4 Equipment Rooms (1) Where walls, partitions, floors or ceilings are used to form hazard-free rooms or sections, they shall be: a) of substantial construction; b) built of or lined with noncombustIble material; and c) such as to ensure that the rooms or section will remain free from hazards. '
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ELECTRICAL INSTALLATION OF BUILDINGS
(2) Where a non-hazardous location within abuilding communicates with a Class I, Division 2 location, a Class IT location, or a Class ill location, the locations shall be separated by close-fittings, self-closing,. approved fire doors. 12.4.5 Cable Trays (1) Cable trays shall not be used to support cables in hazardous locations except where: .
a) the type of cable is approved in Clauses of this Section for use in the particular hazardous location; and b) there can be no hazardous accumulation of combustible process dust or fibre in or upon the cable; the cable tray or the supports.
u.s
CLASS I LOCATIONS
12.5.1
Installations in Class I, Divisiop 1 Locations
12.5.1.1
Transformers and capacitors
(1) Transformers and electrical capacitors which contain a combustible liquid that will burn . shall be installed in electrical equipment vaults in accordance with applicable Clauses of Section 11. 12.5.1.2
Meiers, instmments and relays
(1) Where practicable, meters, instruments and relays, including kilowatt-hour meters, instrument transformers and resistors, rectifiers and thermionic tubes shall be located outside the hazardous locations. (2) Where it is not practicable to install meters, instruments, and relays outside Class I, Division 1 locations, they shall be approved for Class I locations: 12.5.1.3 Switches,'motor controllers, circuit breakers and fuses (1' Switches, motor controllers, circuit breakers and fuses, including push buttons, relays, and similar devices shall be provided with enclosures; the enclosure in each case, together with the enclosed apparatus, shall be approved as a complete assembly for use in Class I locations. ,
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SECTION 12: HAZARDOUS LOCATIONS
12.5.1.4 Motors and generators
(1) Motors, generators and other rotating electrical machines shall be approved for Class I locations. 12.5.1.5
Wiring methods'
(1) The wiring method shall be 'thre~ded rigid-metal conduit or cables approved for hazardous locations with associated cable glands approved for the particular hazardous location. (2) All boxes, fittings, and joints shall be threaded for conrtection to conduit or cable glands, and shall be explosion-proof with boxes and fittings approved for Class I locations. (3) Threaded joints shall have at least five full threads fully engaged and running threads shall not be> used. (4) Cables shall be installed and supported in a manner to avoid tensile stress atJ.b~. .cable glands. .,' ,··: using a bath or a shower, iris admissible for the switch to be placed adjacent to thenormal access door of the room, or to be of the type operated by insulating cord. (4) The switch or switches providing control of comprehensive lighting installation comprising more than one lighting fitting in non-domestic premises may be installed in separate rooms. (5) Where lighting fittings are installed over readily combustible material, every light fitting 'shall be controlled by an individual wall switch. (6) Where stairway in a dwelling unit has risers, the lighting shall be controlled by intermediate wall switches or their functional equivalent located at the head and foot of the' stairway, 15.3.3 Installation of Lighting Equipment
15.3.3.1
Live part,
(1) Luminaries, lampholders, and rosettes shall be installed so that no live part is exposed to contact while they are in use. (2) Where lampholders and switches have exposed accessible terminals, they shall not be installed in metalluminaire canopies or in open bases of portable lamps.
15.3.3.2
Support,
(1) Every luminaire, lampholder and rosette shall be securely supported. (2) Where a luminaire weighs more than 30;ON or exceeds 40.0cm in any dimension, it shall not be supported by the screw shell of the lampholders. (3) Where a non-metallic outlet boxof thermoplastic material, such as, for example, P.V.C, is used to suspend a luminaire, care shall be taken to ensure that the temperature of the box does not exceed 60°C; and the mass suspended shall not exceed 30.0N.
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ELECTRICAL INSTALLATION OF BUILDINGS
(4) Where the weight of a luminaire does not exceed lOO.ON, it shall be permitted to be supported by an outlet box that is mounted on a bar hanger.
a
(5) Where luminaireweights more than 100.0N, it shall be suspended independently of the outlet box, or by means of an acceptable fixture hanger with integral outlet box. 15.3.3.3
Outlet boxes to be covered
(1) Every outlet box used with lighting equipment shall be provided with a cover or covered by a luminaire canopy lampholder , rosette, or other device. 15.3.3.4 Recessedluminaries
(1) The recessed portion of every enclosure of a recessed luminaire shall be at least 12.5mm from combustible material at every point other than at a point of support. (2) Every recessed luminaire shall be-so installed that any adjacent combustible material is not subjected to temperature in excess of 90°C. (3) Recessed luminaries shall not ~ used when blanketed with thermal insulation unless the luminaries are marked and approved for this use. 15.3.3.5 Minimum height of luminllries
(1) Where a rigid luminaireor lampholder is located at a height of less than 2.1m above the floor and is readily accessible, the luminaire or lampholder shall be protected 'from mechanical injury by a guard or by location. 15.3.3.6 Luminaire exposed to flying objects
(1) Where luminaries are installed in gymnasiums or similar locations where the lamps are normally exposed to damage from flying objects, the lamp shall be guarded by one of the following means: .a) metal reflectors that effectively protect the lamps, b) metal screens, c) enclosures of armoured glass or suitable plastic material.
322
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SECTION 15: INSTALLATION OF LIGHTING EUUIPMEN:r . .::L
'penir /ithin
15.3.3.7 Luminaire as a raceway
5) A ccessi
(1) Branch circuit conductors run through a luminaire shall be contained ir: which is an integral part of the luminaire except that the conductor of a 2-wic; 4-wire branch circuit supplying the Iuminaire may be carried through:
equin
a)
b)
5) Br
art of
ie
pui
i.3.4.~
.) wr
mnec ith a'
:) Th nctioi
ensu .ting.
I
fHIO
~
a) an installation of luminaries approved and marked for end-to-end ass; ,.;. a continuous channel; or b) luminaries which are connected together by acceptable wiring metl.: (2) Ballasts located within luminaries shali be deemed to be sources of conductors supplying the luminaries shall:
:~,
,.,ceway "',re, or
i-,
farm
:.r, " 'the
a) have a temperature rating not less than90OC;
b) be of type listed in:
i) Section 4, Annex B,as being suitable for use in raceway; or ii) Section 4, Annex B, as being suitable for use :in accordance with this Clause, provided that conductors are not smaller than 2.5mm 2 and do not extend beyond the luminaries through raceway more than 2.0m long.
5.3.4.~
l) Br. iring npaci
r,
15.3.4
Wiring of Lighting Equipment
15.3.4.1
Wiring ()j.luminaries
(1) .All-electricalwiringon orwithin a luminaire, beside ensuring its electrical safety, shall: a)bene:atly arranged without excess wiring;
b) be not exposed 10 mechanical injury;
C) be arranged so that it is not subject to temperatures above those for which it is
approved; and
d) be free from joint or tap Within.an armor stem.
15.3.4.2 Colour coding
,(1) Notwithstanding the requirementsofSection 4 with regard to the colours used for identifyingconductors,acontinuous-coloured tracer in the braid of individual braided conductor shall be permitted for thesu,pplyconductofs of a luminaire.
ETHIOPIAN BUILDING CODE STANDARD
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ELECTRICAL INSTALLATION OF BUilDINGS
15.3.4.3 Conductor cross section and insulation
(1) Luminaries shall be wired with a conductor at least O.5mm2 cross sectional arc a, having insulation suitable for voltage and temperature to which the conductors may be subjected. 15.3.4.4 Conductor on movablepans
(1) Stranded conductors shall be used on chain-type luminaire and other movable parts of lighting equipment. (2) Conductors shall be arranged so that the weight of the luminaire or that of the movable parts does not place undue tension on the connections. (3) All conductors which supply movable parts of lighting equipment shall be protected against mechanical injury. 15.3.4.5 Pendant conductors
(1) Where pendant conductors are longer than 900.0mm, they shall be twisted together. 15.3.4.6 Recessed luminaire wiring
(1) Conductors for wiring recessed luminaire, branch circuit and tap connection shall have insulation suitable for the temperature encountered. (2) Branch circuit conductors shall be permitted to be run directly to the luminaire. (3) Tap connection on" conductors shall: a) not be smaller than l.Dmm'' copper run in a factory-installed raceway or, if raceway is provided but not factory assembled, smaller than 2.5mm2; b) extend at least 150.0mm from the raceway; and c) be installed in a raceway extending at least 450.0mm but not more than 2.0m from the luminaire, and terminate in an outlet box located not less than 300.0mm from the luminaire. (4) The outlet box referred in (3c) above shall be accessible, and if access is through the opening for mounting the luminaire or through some other opening in the ceiling, this
324
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ELECTRICAL INSTALLATION OF aUtLDINGS
15.:'-5
Earthing of Lighting Equipment
15.3.5.1 Genetal (1) Non-current-carrying metal parts of luminaries and associated equipment shall be earthed in accordance with Part I of Section 7.
15.3.5.2
Lampholders
(1) Where centre-contact screw Iampholders are connected to a source of supply having an earthed neutral conductor, the outer or screwed contact shall be connected to that conductor.
(2) Where lampholders in (1) above are used in circuits having neither pole connected with earth or itt any damp situation in which they can readily be touched by a person in contact with or standing on earthed metal, they shan be provided with a protective shield of insulating material or shall be placed or safeguarded so that neither the lamp cap nor the outer or screwed contact of the Iampholder can inadverntly be touched when the lamp cap is engaged with the contact
15.3..6
Electric-Discharge Lighting Systellls Operating at 1000.0V or Less
15.3.6.1
Transformer
(1) Oil,:.fil1ed transformers shall not be used. 15.3~6.2
TltemittJ p1"otection
(1) Luminaries which employ fluorescent lamps shall have thermally protected ballasts except where the ballasts are of the simple reactance type.
15.3.6.3
AUXiliary equipmettt
(t) Reactors, capacitors, resistors, and other auxiliary equipment shan be: a) enclosed within the liminaire; b) enclosed within an accessible; permanently installed, metal cabinet where remote from the luminaire, or
e) acceptable for use without an additionalenclosure.
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SECTION 15: INSTALLATION OF LIGHTING EQUIPMENT
(2) The metal cabinet, if not part of the luminaire, shall he installed as close as possible to the Iuminaire. (3)- Where display cases are not permanently installed, no part of a secondary circuit shall . . . be included in more than one case. 15~3.6.4
Control
(1) The luminaries and lamp installations shall be controlled by a switch, circuit breaker, or contactor. (2) Where a switch is used as in (1) above, it shall: a) have a current rating of not less than twice the current rating of the lamps or transformers;
b) be a type approved with the assembly; or
c) be a manually-operated general use 380.0V a.c. switch.
15.4
OUTDOOR LlGIITING EQUIPMENT
15.4.1 General 15.4.1.1 Hazard
(1) In outdoor lighting installations, either decorative lighting or illumination of outdoor areas, the protection of the installation and safety from shock hazard shall be the major concern and the fire hazard of the minor or of secondary nature.
15.4.1.2 Ball4st protection (1) Luminaire which employ fluorescent lamps shall have thermally protected ballasts except where the ballasts are of the simple reactance type. 15.4.1.3 Overcurrem potection
(1) Overcurrent protection shall not be provided in a high-intensity discharge luminaire or a separate ballast box unless the combination is approved for the purpose and so marked.
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ELECTRICAL INSTALLATION OF BUILDINGS
15.4.2 Permanent Outdoor Floodlighting Installation 15.4.2.1 General
(1) Clause 15.4.2 shall apply to permanent, outdoor installations of floodlights of 300.0W or larger where the floodlights art; mounted on poles or towers, 15.4.2.2 Service equipment
(1) Service equipment shall comply with Section 5 of this Code; and where indoor installation is installed outdoors, it shall be installed in an acceptable weather-proof enclosure. 15.4.2.3
Wiring methods underground
(1) Underground wiring shall be run: a) where acceptable, in rigid steel or rigid aluminium conduit; b) in non-metallic underground conduit; c) as lead-sheathed armoured cable, mineral-insulated cable, or aluminium-sheathed cable; or d) as conductors or cable assemblies acceptable for earth burial. (2) Conductors buried directly in the earth shall be of types suitable' for use in wet locations. (3) Suitablecorrosion-resistant protection shall be provided for aluminium sheathed cables and aluminium conduits, and also for mineral-insulated cable, if used where materials coming into contact with the cable may have a deteriorating effect on the sheath. 15.4.2.4
Wiring methods on poles
(1) All electrical equipment on a pole shall be controlled by a switch which can be locked in the "Off' position, and each pole shall be provided with a prominent sign warning against climbing the pole until the switch is "Off' unless all conductors and live parts other than those used for pole-top wiring are guarded against accidental contact in one of the following ways: .
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SECTION 15: INSTALLATION OF LIGHTING EQUIPMENT
a) The conductors are run in rigid or flexible metal conduit, as in mineral-insulated cable, or up the centre of steel, aluminium, or hallow concrete poles. b) The conductors and live parts are kept at least l.Om from the climbing ladder or climbing step. c) Barriers are provided between conductors or live parts, or both, and the climbing ladder so as to prevent a likelihood of contact by the climber. .' (2) Conductors running up the centre of poles shall be supported so as to prevent injury to the conductors inside the pole and so as to prevent undue strain on the conductor where they leave the pole. (3) Where vertical conductors, cables, and earthing conductors are within 2.5m of locations accessible to unauthorized persons, they shall be provided with a covering which gives acceptable mechanical protection. (4) On wood poles, for earthing conductors from lightning arresters, the protective covering specified in (3) above shall be of wood moulding or other insulating material giving equivalent protection. (5) Where there is more than one branch circuits on a pole top, the feeders shall be run to a distribution panelboard which shall be either weather-proof or installed in a weather proof enclosure. Note:
The panelboard may be omitted where there are two branch circuits on a 230/380.0V circuits with a common neutral Iineand where there are three branch circuits on a 230/380.0V,3-phase, 4-wire circuits.
(6) Pole-top branch circuit wiring, exclusive of leads approved with floodlights to which they are connected, shall be run: a) as lead-sheathed cable or rubber or thermoplastic-insulated, moisture-resistant types of conductors installed in rigid conduit; or b) by special permission, as insulated or uninsulated exposed wiring provided that: i) the wiring is supported on a suitable insulator; ii) the wiring is controlled by a switch which can be locked in the "Off' position; and iii) the pole is provided with a prominent sign warning against climbing it until the switch is "Off'.
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ELECTRICAL INSTALLATION OF BUILDINGS - -----
-- -._------~-- , . - - - - - - - - - - - - - - - - - - - - - - - - - -
(7) There shall be no joints or splices concealed within conduit; but open taps and joints may be made in pole-top exposed wiring provided the joint or lap is given insulation equivalent to that on the conductors jointed. (8) Transformers shall comply with the following: a) If mounted on floodlight poles, all live parts shall be guarded as required by (1) above. b) If mounted on poles, the bottom of the transformer shall be at least 5.0m above
locations accessible to unauthorized persons. c) If located on platforms on the ground, they shall be completely enclosed so as to prevent access by unauthorized persons or they shall be surrounded by a protecting /'
fence,
(9) Switches controlling floodlights shall comply with the following: a) A switch on the primary side of a transformer shall be capable of making, and interrupting the full-load on the transformer. b) Switches controlling floodlights from tIre secondary side of a transformer shall have a current rating not less than 125% of the current requirements of the floodlights they control. c) Switches shall be capable of being' operated either by remote operation or by proper guardingwithout exposing the operator to danger of contact with live parts. d) Switches shall be capable of being locked in the "Off' position. The secondary earthed-circuit conductor may be earthed by interconnecting to the primary earthed circuit conductor provided that: (10)
a) the primary is earthed at the transformers, and
b) interconnection is made at the transformer.
Except for isolated metal parts such as cross bars, bolts; insulator pins, and the like, all non-current-carrying metal parts of the electrical equipment at the pole-top shall be bonded together and, if within reach of any earthed metal, they shall be earthed. (11)
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ETHIOPIAN BUILDING CODE STANDARD
-
SECTION 15: INSTALLATION OF LIGHTING EQUIPMENT
15.4.3
Exposed Wiring for Permanent Outdo".. Lighting
15.4.3.1
General
(1) Clause 15.4.3 shall apply to exposed wiring for permanent outdoor lighting other than floodlighting where the circuits are run between buildings, between poles, or between buildings and poles.
15.4.3.2 Conductors (1) Conductors shall be stranded copper, not less than 205m2, and shall be: a) of a type suitable for exposed wiring where exposed to the weather; b) of the rubber-insulated type suitable for exposed wiring where exposed to the weather when lampholders of a type which puncture the insulation and make contact with the conductors are used; or c) of the moisture-resistant, rubber-insulated type suitable for exposed wiring where exposed to the weather if cabled together and used with messenger cables.
15.4.3.3 Use of insulators 15.4.3.3.1 Conductors attachment (1) Conductors shall be securely attached to insulators. at each end of the run if a messenger is not used and at the intermediate points of support, if there are any. 15.4~3.3.2
Type of insulator
(1) Insulators at the ends of runs shall be of the strain type unless the conductors are supported by messenger cables. 15.4.~.3.3
Split knobs
(1) Split knobs shall not be used.
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ELECTRICAL INSTALLATION OF BUILDINGS
15.4.3.3.4 Height of conductors
(1) Conductors supplying lamps in parking lots, used-car lots, drive-in establishments and similar commercial areas shall be maintained such that the conductors or the bottom of a lamp fed from the conductors, whichever is lower, shall have a clearance of not less than 4.0m above grade at any point in a run, except that where a driveway or through fare exists, this clearance shall not be less than 4.0m. 15.4.3.5
Spacing from combustible material
(1) Conductors and lampholders shall be maintained at a distance not less than 1.0m from any combustible material except for branch circuit conductors at the point of connection to buildings or poles. 15.4.3.6
Spacing of conductors
(1) Conductors shall be separated at least 300.0mm from each other by means of insulating spacers at intervals of not more than 4.5m unless the conductors are secured to and supported by messenger cables. 15.4.3.7
Lampholders
(1) Lampholders shall: a) be of weatherproof types, with moulded insulating bodies;
b) be of types having either:
i) permanently attached leads; or ii) terminals of a type which puncture the insulation and make contact with the conductors; c) have, when with permanently attached leads, the connection to the circuit wires staggered where a cabled assembly is used.
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SECTION 15: INSTALLATION OF LIGHTING EQUIPMENT
15.4.3.8
Use of messenger cables
(1) Messenger cables: a) .shall be used to support the conductors: i) if lamp holders having permanently attached leads are used, and the span exceeds 12.0m; and ii) in all cases where lampholders having termination which puncture the insulation are used; b) shall be securely attached at each end of the run and shall be earthed. 15.4.3.9
Construction of messenger cables
(1) Messenger cables shall be of galvanized steel, copper-coated steel, or stainless steel, and shall be of a stranded construction with no less than seven strands. (2) The effective ultimate strength of a messenger cable shall not be less than 3 times the calculated maximum working load and in no case shall the individual strands be less than: a) 1.168mm in diameter in the case of galvanized or copper-coated wire; or
b) 1.112mm in diameter in the case of stainless steel wire.
15.4.3.10 Branch circuit loading and protection
(1) Branch circuits shall be protected by overcurrent devices rated at not more than 32.0A. (2) The total load on a branch circuit shall not exceed 80% of the rating or setting of the overcurrent devices.
ETHIOPIAN BUILDING CODE STANDARD
EBCS-10 1995
333
ANNEX'
A(NORMATIVE)
LIGHTING COLUMNS,
A.1
TERMS IN THE FIELD OF LIGHTING COLUMNS
Lighting column
a support intended to hold one or more lanterns, consisting of one of more parts: a post, possibly an extension piece and, if necessary, a bracket. It does not include columns for catenary lighting.
nomi1lll1 height
the distance between the centreline of the point of entry of the lantern and the intended ground level for a column planted in the ground, or the flange plate, for a column with a flange plate as shown in Figure A.1.
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,')
I '
.~ J . II
'~,. , ~
'L"
"L.,;"Ii ...
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Figure A.l Nominal height
334
EBCS",10 1995
ETHIOPIAN BUILDING CODE STANDARD
SECTION 15: INSTALLATION OF LIGHTING EQUIPMENT
posMOp column
a straight column without bracket to support the lantern (post-top lantern) directly.
column with bracket
a column to support a lantern or lanterns (side-entry lanterns) by means of one or more brackets which are integral with, or demountable from, the column.
bracket
a component used to support a lantern at a definite distance from the axis of the lower straight portion of a single, double or multiple form column and integral with, or demountable from, the column.
bracket projection
horizontal distance from the point of entry to the lantern to a vertical line passing through the center of the cross section of the column at the ground level as shown in Figure A.2.
I
the shape
of the bracket
is not ~pecified
in this standard
'\ ).
.i.> Figure A.2 Bracket projection bracket fixing
the connecting part on a column for securing a separate bracket. It may be of the same size or a different cross section from the column.
lantern .fixing
the connecting part on the end of a post-top column or of a bracket for securing a lantern. It may be the end of the column or the bracket itself or an additional part having the same or a different cross section from the column or bracket.
ETHJOPIAN BUILDING CODE STANDARD
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ELECTRICAL INSTALLATION OF BUILDINGS
angle between the axis of the lantern fixing and the horizontal.
lantern .fixing angle
opening in a column for access to electrical equipment.
door opening
opening in a column below ground for cable entry.
the length of a column below the intended ground level as shown in
Figure A.3.
cable entry slot planting depth
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)
"
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t
,
1b,Plan.hng dep.tl\
Figure A.3 Planting,depth
plate below ground level fixed to a planted column sinking into the ground and to help prevent the column overturning as shown in Figure A.4.
base plate
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,)
"
Base plate
Figure A.4 Base plate
336
EBCS-10 1995 _
ETHIOPIAN BUILDING CODE STANDARD
SECTION 15: INSTALLATION OF LIGHTING EQUIPMENT
a plate with an opening for cable entry, attached rigidly to a column which is surface mounted, to allow it to be secured to a concrete foundation or other structures as shown in Figure A.S.
flange plate
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)
. '-----
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Flange plate
Figure A.5 Flange plate A.2
DIMENSIONS AND TOLERANCE
A.2.1
Requirements
The dimensional requirements are specified except that the connection dimensions in Clause A. 2.7 represent a recommended choice.
ETHIOPIAN BUILDING CODE STANDARD
EBCS-10 1995
337
ELECTRICAL INSTALLATION OF BUiLDINGS it
A.2.2 Post top columns, main dimensions (in meters)
~ I.
For to.lerana:s for d~mcnsions and shape see clause 8
I
'NClmin.1
height
h
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1
-
5 6
--
.c:
S 10
.
12
-
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18
.....
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For dimensions for door openings and cable entry s"lots see clause A2~~
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1. 1
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Type Al
A.?.s
Type A2
For column foundation see clause A
338
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20
EBCS-101995
". $ @j
For llange :plate see -clause 'AI.'
Type A3
1.5
ETHlOPIANBUILPfNG CODE STANDARD
SECTION 15: INSTALLATION OF LIGHTING EQUIPMENT
A.2.3 Columns with brackets, main dimensions (in meters)
Connection dimensions heli clouse A2.1) Lantern fixing ong'lt 5" or 15"
The shape of the bracket not specified In this standard
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)
For tolerances for dimensions and shape. see clause Al.8
'
Nomlnll h.lght
h
Pro/.ctlon
w"
5
-e
6 8
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~ see clause Type 81
Type 82
For column foundallon see clause
1.25
10
2
12
3
15
For dimensions for door opening,'and cable entry slots see clause "'2.4
+
0.75
18
+
~
~
m
For flange plate see clause A2. ~
Type 83
A2.5
11 It is 'ecommondod Ihll W l!ono,"lIy should b. equll 10. 0' loss Ihon.1
ETHIOPIAN BUILDING CODE STANDARD
EBCS-10 1995
339
ELECTRICAL INSTALLATION OF BUILDINGS
A.2.4 Door openings and cable entry slots (dimensions in millimetres)
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Cellar
Figure A.1 Example - Automatic If=
ti~e
alarm system
:=---. '''~' 1/'
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c- '"
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Figure A.2 Example device
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.~
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UE
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.,
''''n~_
"Melll"!1
Automatic tire alarm systems with non-automatic tire alarm
ETHIOPIAN BUILDING CODE STANDARD
EBCS-10 1995
363
ELECTRICAL INSTALLATION OF BUILDINGS
~
3/3
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~III
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el."n kwhCl'.' tfAAI
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Figure A.3 Installation plant of a fire alarm system with block circuit diagram
364
EBCS-10 1995
ETHIOPIAN BUILDING CODE STANDARD
ANNEX
B (INFORMATIVE)
CIRCUIT DESIGN
B.l MANUAL AND AUTOMATIC B.l.l
CA~L
POINT CIRCUITS
Introduction
Whilst there are but two basic call point control circuits, i.e. 'open circuit' and 'closed circuit', simple definition of each can be misleading because, in practice, there are employed numerous variations and combinations of each circuit. The type of circuit to be used should be determined by careful consideration of the functions required from the fire alarm system in the particular building concerned, taking into account simplicity, reliability, liability to damage, operational supervision, cost, environment and such other relevant factors. It is unwise to assume, in general, that one type of circuit is better than another. Four simplified but typical, circuits are given below. Alarm and fault-sensing units may be relays, solid-state circuits or similar devices; call points may have mechanical contacts, solid state circuits, variable-resistance devices, etc. It should be appreciated that many other circuit arrangements are possible and the following circuits should in no way be considered other than for the purpose of illustration.
//
B.l.2 Circuit 1 - Open circuit
Alarm-sensing unit
/ .
Di--"--·----'----·
o
r--I /1
'---1
supply
- I!
Figure B.l Open circuit
)/
::J
Open Circuit Call Point
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Current flows when the call point contacts are closed, causing the alarm-sensing unit to operate and initiate an alarm signal. A broken connection/conductor will prevent a call point beyond the break from operating the alarm-sensing unit. A short-circuit between conductors will cause the alarm-sensing unit to operate, producing an alarm signal. In this circuit, the alarm-sensing unit could be the alarm sounder.
B.l.3 Circuit 2 - Closed circuit
Alarm-Sensing Unit 0--
I
supply
o
0
I
0
,I
I
Closed circuit call point Figure B. 2 Closed circuit
. Current is normally flowing through the conductors and call points; the alarm-sensing unit is hand operated. When a call point's contacts are opened, the current is interrupted allowing the alarm-sensing unit to release and initiate an alarm signal. A broken connection/conductor interrupts the current to the alarm-sensing unit, initiating an alarm signal.
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SECTION 16: FIRE ALARM SYSTEM AND FIRE PUMPS
A short-circuit between conductors will allow the current to by-pass call points ,beyond the short-circuit; thus, a call point beyond the short-circuit cannot interrupt the current and cannot, therefore, initiate an alarm signal. B.1.4 Circuit 3 - Combination of open and closed circuits, Type A High-current ~ Limiting resistor Sensing Unit(alarm)
supply
o
--+--
1\/1
I
Low-current L Open circuit call point sensing unit (fault)
Figure B.3
Combination of open and closed circuits, Type A
The conductors are closed-circuit connected; a resistor limits the current through two sensing units to a value sufficient to hold operated the low-current (faults) sensing unit, but insufficient to operate the high-current (alarm) sensing unit Open circuit call points are connected across the conductors. Operation of a call point allows the current to by-pass the resistor. The resultant increase in current operating the high-current (alarm) sensing unit which initiates an alarm signal. A broken connection/conductor will interrupt the current, releasing the low-current (fault) sensing unit:which initiates a fault signal. A short-circuit between conductors by-passes the resistor, the resultant increase in current operates the high-current (alarm) sensing unit, which initiates an alarm signal.
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B.l.S . Circuit -I - Combination open and closed circuits, Type B Medium-current Sensing unit (alarm>/ Open circuit call point ~
I
I
-I 0
,0
,~---
Supply
o
i
I Low-current sensing unit (fault)
Limiting resistor
call· point resistor
Figure B.4 Combination open and closed cireuits, Type B
The conductors are "closed circuit" connected, the open-circuit call points being wired in series, their contacts being bridged by resistors. The values of the call point resistors and of the limiting resistor are carefully chosen to ensure that the correct current flows in the circuit during the various conditions of fault and alarm. Under normal conditions, the current flowing in the circuit is sufficient to hold the low-current (fault) sensing unit operational, but is insufficient to operate either the medium- or the high current alarm or fault-sensing units. Operation of a call point by-passes its call point resistor. The resultant increase in current is . sufficient to operate the medium-current alarm-sensing unit, which initiates an alarm signal, but is insufficient to operate the high-current fault-sensing unit. A broken connection/conductor will interrupt the current, releasing the low-current fault-sensing unit which initiates a fault signal. A short-circuit between conductors by-passes the limiting resistor. The resultant increase in current is sufficient to operate both the medium-current alarm and the high-current fault-sensing units. The former's attempt to initiate an alarm signal is overridden by the latter and a fault signal is initiated. Study of the above circuits will indicate that each circuit has advantages and disadvantages. Some of these are outlined in Clause B.2.
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SECTIO~I
16: FIRE ALARM SYSTEM AND FIRE PUMPS
B.2
ADVANTAGESAl~DISADVANTAGESOFVARIOUSCALLPOINTCIRCUITS
b.2.1
Circuit 1
a) Advantages i) This is a simple and reliable circuit. ii) No current is consumed on stand-by; therefore, a battery and charger of moderate size and cost may be used. iii) A broken connection or conductor will not result in a false alarm, b) Disadvantages There will be no indication of a break in the circuit which may make some parts of the system inoperative. ii) A short-circuit between conductors will produce a false alarm. i)
iii) The call points are not monitored. B.2.2 Circuit 2
a) Advantages . i) This is a simple and reliable circuit.
ii) The call points are monitored.
iii) The contacts and connections are monitored.
b) Disadvantages i)
Current is consumed on stand-by; therefore, the size and cost of the battery and charger will be increased. ii) There will be no indication of a short-circuit between conductors which may make some parts of the system inoperative. iii) A broken connection or conductor will cause false alarm.
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B.2.3 Circuit 3 Type A a) Advantages' i) The conductors are monitored. ii) An open circuit of a connection or a conductor will produce afault signal; not a false
alarm. b) Disadvantages
i) Current is consumed on stand-by.
ii) A short circuit between conductors will cause a false alarm.
iii) The call points are not monitored.
B.2.4 Circuit 4 Type B
a) Advantages
i) The conductors are monitored. ii) An open circuit of a connection or a conductor will produce a fault signal, not a false alarm. iii) A short-circuit between conductors will produce efault signal, not a false alarm. b) Disadvantages
i) Current is consumed on stand-by. ii) The selection of values of call-point resistors and limiting resistors is critical. A number of call points operated together may result in a fault signal instead of an .alarm signal. iii) There is a need for introduction of additional and complex sensing equipment.
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. ETHIOPiAN BUILDING CODE STANDARD
SECTION
17
SIGNS AND OUTLINE LIGHTING
17.1
SCOPE
(1) This provisions of this Section apply to the installation of signs and outline lighting wherein the source of light w:e: a) b) c) d)
incandescent lamps,
fluorescent lamps,
high-voltage luminous discharge tubes including neon tubes, and
high intensity discharge lamps.
Note:
The word "sign", when used throughout this Section, includes those of the through-wall type.:
17.2
NORMATIVE REFERENCES
(1) The following references contain provisions which, through reference in this text, constitute provisions of the Ethiopian Building Code Standard on Electrical Installation of Buildings.
17.3
a) IEE:1970
The Institute of Electrical Engineers, Regulation for the Electrical Equipment of Buildings, Fourteenth Edition (1966), Incorporating Amendments.
b) C22,1: 1990
Canadian Electrical Code, Part 1, Safety Standard for Electrical Installation, Sixteenth Edition
GENERAL REQUIREMENTS
17.3.1 Construction (1) All signs and outline lighting apparatus, accessories, and fittings manufactured wholly or in part in the field shall comply with the relevant requirements of:
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a) this Code; and b) the applicable international standards, if any, except so far as these requirements may be modified by this Code.
17.3.2 Disconnecting Means (1) Each outline lighting installation and each sign other than the portable type shall be provided with a disconnecting means which shall: a) open all unearthed conductors;
b) be suitable for condition of installation such as exposure to weather; and
c) be integral with the sign or outline lighting.
17.3.3 Rating of Disconnecting Means and Control Devices (1) Switches, flashers, and similar devices breaking inductive loads shall be either of a type approved for the purpose or have a current rating of not less than twice the current rating of the loads.
17.3.4 Thermal Protection (1) Ballasts of the thermally-protected type shall be required for all signs and outline lighting which employ fluorescent lamps except where the ballasts are of the simple reactance type.
17.3.5 Branch Circuit Capacity (1) Circuits shall be arranged so that the load imposed by lamps and associated gears shall not exceed 80% of the branch circuit overcurrent protection.
17.3.6 Location (1) Signs and outline lighting shall be located so that all the following requirement are met: a) Any person working thereon is not likely to come into contact with overhead conductors. b) No part of the sign or its support will interfere with normal work operations performed on electrical and communication utility lines. c) No part of the sign or its support is in such proximity to overhead conductors as to constitute a hazard.
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SECTION 17: SIGNS AND OUTLINE LIGHTING
d) Unless mechanical protection is provided to prevent persons or vehicles from coming into contact with the electrical components of the sign, no part of the sign, other than its support, shall be located within 202m above grade. 17.3.7 Bonding (1) All conductive non-current-carrying parts of the lighting installation shall be bonded to earth in accordance with the requirements of Section 7 except for conductive parts of letters attached to the building and illuminated from the rear. 17.3.8 Protection of Sign Leads (l) Sign leads which pass through the walls or partitions of the sign structure shall be protected by non-combustible, moisture-absorption resisting bushings.
17.3.9 Installation of Conductors (l) Conductors for sign and outlying lighting shall be installed in accordance with the requirement of Section 8.
17.3.10 Fuseholders and Flashers (l) Fuseholder, flashers, etc. shall be enclosed in metal and shallbe accessible without the necessity of removing obstructions or, otherwise, dismantling the sign.
17.4
IDGH-VOLTAGE LUMINOUSDISCHARGE TUBE SIGNSANDOUTLINE LIGHTING
17.4.1 Enclosure
17.4.1.1
Cleneral
(l) Enclosure for transformers, switches, timers, relays, sequencing units and other similar devices shall be of metal or of heat and moisture resistant, non-combustible material.
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.~
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17.4.1.2 Construction (1) The enclosure shall be constructed to prevent the emission of flames or any burning or ignited material.
17.4.1.3
Ventilation
(1) Openings for ventilation shal! be-arranged to comply with the requirement of 17.4.1.2 shall at least be lOO.Omm from live parts. 17.4.1.4
and
Thickness
(1) Metal enclosures shall not be less than O.8mm thick and at the point where it is intended
that the supply connections be made, the enclosure shall be of not. less than 1.6mm in thickness. 17.4.1.5
Marking
(1) Each enclosure housing a transformer shall be marked in accordance with the requirements
of Clause 2.4.6.
1704.2 Proteetlon of Uninsnlated Part (I) Doors or covers accessible to the general public and which give access to uninsulatedparts
of indoor signs or outline lighting shall either be provided with interlock switches which, on the opening of the doors or covers, disconnect the primary circuit or shall be fastened so that the use of other than ordinary tools will be necessary to open them.
1704.3 Transformers 17.4.3.1
Secondary voltage
.(1) The rated secondary open-circuit voltage of transformers shall not exceed 15.0kV, except as in (2) below. (2) In end-earthed transformers, rated secondary open-circuit voltage shall not exceed 7.5kV.
.
I: ....,. .
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SECTION 11: SIGNS AND OUTLINE LIGHTING
17.4.3.2.
Open core-and-coil type transformer
(1) Open core-and-coil type transformers shall only be used indoor.
17.4.3.3 Transformers used outdoors (1) Transformers used outdoor shall be of the weather-proof type or shall be enclosed in the sign body or in a separate weather-proof box.
17.4.3.4 Installation (1) Transformers shall be installed in such location that they are accessible and capable of being removed and replaced. (2) They shall be supported by attachment to the enclosure in which they are housed by at least two studs or bolts.
17.4.3.5 Overcurrent protection (l) Each transformer shall be protected by an overcurrent device except that two or more transformers may be protected by one ove-current device if their combined load does not exceed 12.0A.
17.4.4 High-Voltage Wiring Methods
17.4.4.1
Conductor installation
(1) High-voltage conductors shall be installed in: a) b) c) d) e)
transformer enclosure,
sign enclosure,
flexible metal conduit,
rigid conduit, or
other acceptable type of raceways except for surface raceways.
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17.4.4.2
Conductors run
(1) High-voltage conductors may be run from the ends of gas tubes to the earthed midpoint of transformers which have terminals at the midpoint.
17.4.4.3
Bends
(1) There shall be no bends in high-voltage conductors.
17.4.4.4
Type of conductors
(1) All high voltage conductors installed inside metal sign enclosures shall be of the luminous-tube-sign type cables.
17.4.4.5
Length of cable from transformers
(1) In a metalic raceway and in a non-metallic raceway, cables not more than a total of 6.0m and 16.0m, respectively, shall be run from transformer to other parts of the sign.
17.4.4.6
Connection of conductors
(1) Connection of high-voltage conductors to neon tubing outside the building or structure shall be made by means of one of the following.
a) an electrode receptacle; b) a direct connection in the neon tubing outside the building or structure wall provided that not more than 1.0m of high-voltage wiring extends beyond the end of the raceway; c) any other acceptable methods. Note:
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The connection in (b) shall be electrically secure and provided with acceptable wrapping of insulating tape.
EBCS-10 1995
ETHIOPIAN BUILDING CODE STANDARD
· SECTION
18
LIFTS, ESCALATORS· AND SIMILAR EQUIP:MENT
18.1
SCOPE
(l) This Section applies to the installation of electrical equipment for passenger, good's or dual-purpose elevators (lifts), including dumbwaiters, escalators, movmg walks, freight platform lifts, and elevating devices for the handicapped.
18.2
NORMATIVE REFERENCES
(1) The following references contain provisions which, through reference in this text, constitute provisions of the Ethiopian Building Code Standard on Electrical Installation of Buildings.
18.3 'I
a) C 22.1: 1990
Canadian Electrical Code Part 1, Safety Standard for Electrical Installations, Sixteenth Edition.
b) NFPA 701NEC: 1986
National Fire Protection Association!American National Electrical Code, 1987 Edition.
GENERAL
18.3.1 Voltage Limitation (1) The nominal voltage used for lift operating control and signalling circuits, operating
equipment, driving machine motors, machine brakes, and motor generator sets shall not exceed the following: a) 380.0V for operating control and signalling circuits and related equipment, including door operator motors. b) 750.0V for driving motors, machine brakes, and motor-generator sets.
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Exemption:
Higher voltages shall be permitted for driving motors of motor generator sets.
18.3.2 Live Parts Enclosed (1) All live parts of electric apparatus in hoistways, at landings or in or on the cars of lights and dumbwaiters or in the well-ways or the landing of escalators, or moving walks shall be enclosed to protect against accidental contact.
18.4
CONDUCTORS
18.4.1 Installation of Conductors
18.4.1.1
Hoistway door interlocking wiring
(1) The conductors to the hoistway door interlocks from the hoistway riser shall be flame-retardant and suitable for temperature of not less than 200°C.
18.4.1.2
Travelling cables
(1) Travelling cables used as flexible connections between the lift car and the raceway shall be of the types of lift cables or other approved type.
18.4.1.3
Other wiring
(1) All conductors in raceways, in or on the cars of lifts and dumbwaiters, in the well-ways of escalators and moving walks, and in the machine room of lifts, escalators, and moving walks shall have flame-retardant insulation.
18.4.1.4 lnsulation rating (1) All conductors shall have an insulation voltage rating equal to at least the maximum nominal circuit voltage rating of any conductor within the enclosure, cable or raceway.
18.4.2 Minimum Size of Conductors (1) The minimum size of conductors used for lifts, dumbwaiters, escalators, and moving walk wiring, other than conductors that forms an integral part of control equipment, shall be as follow:
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SECTION 18: LIFTS, ESCALATORS AND SIMILAR EQUIPMENT
a) for lighting circuits, I.Smm"; and
b) for operating control and signalling circuits, 0.5mm2 •
. 18.4.3 Motor Circuit Conductors
(1) Conductors supplying lifts, dumbwaiters, escalator, or moving walk motors shall have an ampacity of: (a) (b)
18.5
if supplying single motor, not less than 150% of the motor full-load current rating. if supplying two or more motors, not less than 125% of the nameplate current rating of the highest rated motor in the group plus the sum of the nameplate current ratings of the remainder of the motors in the group.
WIRING
18.5.1 Wiring Methods
18.5.1.1 In hoistway, machine rooms, and escalator wellways (1) Conductors located in hoistway, machine rooms and escalator well-ways, except travelling cables, shall be installed in rigid metal conduit, electrical metallic tubing, or metal wireways, except that flexible metal conduit or armoured cable shall be permitted only if not subjected to mechanical damage. Exemption: Mineral-insulated cable or aluminium-sheathed cable may be used if located so that there is no liability
of damage to the sheath.
18.5.1.2 On cars (1) Conductors on lift and dumbwaiter cars shall be run in rigid metal conduit, electrical metallic tubing, or wireways, except that: a) short runs of flexible metal conduit or armoured cable may be used where they are securely fastened in place and not exposed to oil or grease; b) hard usage flexible cord shall be permitted to be used between fixed wiring on the car and switching or sensing devices on the door or gate, and. between the fixed car top inspection light and an extension light controlled by the SlUlle switch, provided it is securely fastened and so located as to not be subject to mechanical injury;
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c) mineral-insulated cable.or aluminium-sheathed cable may be used iflocated so that there is no liability or damage to the sheath.
18.5.2
Branch Circuits for Auxiliary Systems
18.5.2.1
Car lighting and accessories
(1) In passenger lifts, at least one branch circuit shall be provided solely for the lighting and accessories on each car.
18.5.2.2
Air conditioning
(1) Where air conditioning units are installed on the car, they shall be supplied by separate branch circuits.
18.5.2.3
Protection device location
(1) The overcurrent device protecting each branch circuit shall be located in the machine room.
18.6
INSTALLATION OF CONDUCTORS
18.6.1 Number of Conductors in Raceway (1) The sum of the cross-sectional area of the operating and control circuit conductors in raceways shall not exceed 40% the interior cross-sectional area of the raceway.
18.6.2 Supports (1) Supports for cables or raceways in a hoistway or in an escalator or moving walkways shall be securely fastened to the guide rail or to hoistway well-way construction.
18.6.3 Different Systems in One Raceway or Travelling Cable (1) Conductors for operating, control, power, signalling and lighting circuits of 600.0V or less shall be permitted to be run in the same travelling cable or raceway system if all conductors are insulated for maximum voltage found in the cables or raceway system and if all live parts of the equipment are insulated from earth for the maximum voltage.
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(2) Such travelling cable or raceway in (1) above shall be permitted to include shielded conductors and/or one or more coaxial cable if such conductors are insulated for the maximum voltage found in cable or raceway system. Conductors shall be pennitted to be covered with suitable shielding for telephone, audio, video or higher frequency communication circuits.
18.6.4 Wiring in Hoistway (1) Main feeders for supplying power to lifts and dumbwaiters shall be installed outside the hoistway (hoist shaft). Note:
Only wiring, raceways, and cables that are or form part of lift or dumbwaiter installation, including wiring for signals, for communication with the car, for lighting, heating, air conditioning and ventilating the car, for fire detecting systems, for pit pumps, and for heating and lighting the hoistway, shall be permitted inside the hoistway.
18.6.5 Electric Equipment in Garages and Similar Occupancies (1) Electric equipment and wiring used for lifts, dumbwaiters, escalators, and moving walks in garages shall comply with the requirements of Section 12 (Class I locations). Wiring and equipment located on the underside of the car platform shall be considered as being located in the hazardous area.
18.6.6 Sidewalk Lifts (1) Sidewalk lifts with sidewalk doors located exterior to the building shall have all electrical wiring in metallic tubing and all electrical outlets, switches, junction boxes and fittings shall be weather-proof.
18.7
TRAVELLING CABLES
18.7.1 Suspension (1) Travelling cables shall be so suspended at the car and hoistway's ends as to reduce the strain on the individual copper conductors to a minimum and shall be supported by one of the following means: a) by its steel supporting members;
b) by looping the cable around supports for unsupported lengths less than 30.0m;
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ELECTRICAL INSTALLATION OF BUILDINGS
c) by suspending from the supports by means that automatically tightens around the cable when tension is increased for unsupported lengths upto 60.0m.
18.7.2 Hazardous (Classified) Location (1) In hazardous (classified) locations, travelling cables shall be of a type approved for hazardous (classified) locations and shall be secured to explosion-proof cabinets.
18.7.3 Protection Against Damage (1) Travelling cable supports shall be so located as to reduce to a minimum the possibility of damage due to the cable coming into contact with the hoistway construction or equipment in the hoistway; and where necessary, suitable guards shall be provided to protect the cable against damage.
18.7.4 Installation (1) Travelling cable shall be permitted to be run without the use of raceway or conduit for a distance not exceeding 1.8m from the first point of support on the lift car or hoistway wall provided the conductors are grouped together and tapped or corded or in the original sheath. (2) Travelling cables shall be permitted to be continued to lift control panels and to lift car and machine room connections as fixed wiring provided they are suitably supported and protected from damage.
18.8
DISCONNECTING MEANS AND CONTROL
18.8.1 General (1) Lifts, dumbwaiters, escalators, and moving walks shall have a single means for disconnecting all unearthed main power supply conductors for each unit.
(2) Where multiple driving machines are connected to a single lift, escalator, moving walk or pumping unit, there shall be one disconnecting means to disconnect the motor(s) and control devices.
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(3) Where there is more than one driving machine in a machine room, disconnecting means shall be number-marked to correspond to the number-mark of the driving machine which they control.
18.8.2 Type (1) The disconnecting means shall be an enclosed, externally operable, fused motor circuit switch or circuit breaker to be locked in the open position.
(2) No provision shall be made to close the disconnecting means in (1) above from any other part of the premises; nor shall circuit breakers be opened automatically by a fire alarm system.
18.8.3 Location (I) Disconnecting means shall be located where they are readily accessible to qualified persons;
18.8.4
Phase Protection
18.8.4.1
Electric lifts
(1) Lifts. dsivenby polyphase alternating current shall be provided with a means to prevent starting ofthe lift when: a) the phase rotation is in the wrong direction, or
b) there is a failure in any phase.
18.8~4.2
Hydraulic lifts
(1) Hydraulic lifts powered by a polyphase alternating current motor shall be provided with the means to prevent overheating of the drive system (pump and motor) due to phase-rotation reversals or failure.
18.9
OVERCURRENT PROTECTION
18.9.1 Control and Operating Circuits (1) Control and operating circuits and signalling circuitsshall be protected against overcurrent . in accordance with the requirements of the relevant Clauses of Section 9.
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18.9.2
Motors
18.9.2.1
Non-continuous duty
(1) Duty on lift and dumbwaiter driving-machine motors and driving motors of motor-generators - used with generator field control shall be classed as non-continuous. Such motors shall be' protected against overcurrent in accordance with applicable Clauses of Section 11.
18.9.2.2
Continuous duty
(1) Duty on escalators and moving-walk driving motors shall be classed as continuous. Such motors shall be protected against overcurrent in accordance with applicable Clauses of Section 11.
18.10 MACHINE ROOM 18.10.1
Guarding Equipment
(1) Lifts, dumbwaiters, escalators, and moving walk driving machines, motor-generator sets, motor controllers, and disconnecting means shall be installed in a room or enclosure set aside for that purpose. (2) The room or the enclosure in (1) above shall be secured against unauthorized access.
18.10.2
Clearance around Control Panels and Disconnecting Means
(1) Sufficient clear working space shall be provided around control panels and disconnecting means to provide safe and convenient access to all live parts of the equipment necessary for maintenance and adjustment.
18.11 EARTmNG 18.11.1
Metal Raceway Attached to Cars
(l) Metal raceways attached to lift cars shall be bonded to earthed metal parts of the car with which they come into contact.
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SECTION 18: LIFTS, ESCALATORS AND SIMILAR EQUIPMENT
18.11.2
Electric Lifts
(1) For electric lifts, the frames of all motors, lift machines, controllers, and the metal enclosures of all electric devices in or on the car or in the hoistway shall be earthed in accordance with Section 7.
18.11.3
Non-Electric Lifts
(1) For lifts other than electric and having any electric conductors attached to the car, the metal frame of the car, where normally accessible to persons, shall be earthed in accordance with Section 7. 18.11.4
Method of Bonding
18.11.4.1 Equipment (I) Equipment mounted on members of an earthed structural metal frame of a building shall be deemed to be bonded to earth.
18.11.4.2 Metal car frame supported by cables (1) Metal car frames supported by metal hoisting cables attached to or running over metal sheaves or drums of lift machines and affording metal-to-metal contact therewith shall be deemed to be bonded to earth when the machine is bonded to earth in accordance with Section 7.
18.12 OVERSPEED 18.12.1
Overspeed Protection
(1) Under overhauling load conditions, a means shall be provided on the load side of each lift power disconnecting means to prevent the lift from attaining a speed equal to the governor tripping speed or a speed in excess of,125% of the lift rated speed, whichever is smaller.
(2) Overhauling load conditions shall include all loads upto rated lift loads for goods lifts and all loads upto 125% for the rated lift loads for passenger lifts.
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18.12.2
Motor-Generator Overspeed Device
(1) Motor generators driven by direct current motors and used to supply direct current for the operation of lift machine motors shall be provided with speed-limiting devices that will prevent the lift from attaining, at any time, a speed of more than 125% of its rated speed.
18.13
EMERGENCY POWER
18.13.1
Supply
(1) A lift shall be permitted to operate from an emergency power supply in the event of normal supply failure, provided the lift operates on such emergency power in accordance with the emergency power system requirementsofa recognized international safety code for lifts.
18.13.2
Disconnection
(1) The disconnecting means shall disconnect the emergency power service from the normal power service.
18.13.3
Hydraulic Lifts Disconnecting Means
(1) In the case of hydraulic lifts where emergency power-is supplied from a second source for lowering the car only, thedisconnecting means shall be provided with an auxiliary contact that is positively opened mechanically, the opening not being solely dependent on springs, and connected in the control circuit to prevent movement of the car when the disconnecting means is open.
18.14
MACHINE ROOMS AND HOISTWAY PITS LIGHTING AND AUXILIARY SYSTEMS
18.14.1
Machine Room
18.14.1.1 Lighting
(1) Permanent provision of adequate artificial light shall be made in machine rooms of power lifts.
386
EBCS-10 1995
ETHIOPIAN BUILDING CODE STANDARD
SECTION 18: LIFTS, ESCALATORS AND SIMILAR EQUIPMENT
18.14.1;2 Illumination level (I) Illumination shall he not less than lOO.Olx at floor level.
18.14.•1.3 Lighting swit.eh (I) The machine room lighting switch shall be within easy reach of the entrance to the machine room.
18.14.1.4 Socket outlet (1) At least one duplex (twin) socket outlet connected to 16.0A 'branch circuit supplying no
other socket outlets shall be installed in the machine room.
18.14.2
Hoist Pits
18.14.2.1 Luminaire (l)One or more permanent luminaireequipped with.aguard of metal, safety glass.or suitable 'plastic material shall beprovided in all .pits,
18.14.2.2 Illumination level
The luminaires shall provide an illuminations level of at least 100.01x at the pit floor,
18.14.2.3 Lighting switch (1) A light switch shall be provided and shall be located so as to be accessible from the pit
access door.
18.14.2.4 Socket outlet (I) At least one twin socket outletconnected toa 16,OAbranch circuit supplying no other
socket outlet shall be installed in each pit.
ETHIOPIAN BUILDING CODE STANDARD
EBCS-101995387
\SECTION
19
THEATRE INSTALLATION
19.1
SCOPE
(1) This Section applies to electrical equipment and their installations in buildings or parts' of a building designed, intended, or used for drama, opera, motion picture, or other shows.
19.2
NORMATIVE REFERENCES
(1) The following reference contains provisions which, through reference in this text, constitute provisions of the Ethiopian Building Code Standard on Electrical Installation of Buildings.
a) C22.1:1990
19.3
Canadian Electrical Code, Part 1, Safety Standard for Electrical Installation, Sixteenth Edition.
WIRING METHOD
(1) Wiring in stage and stage wing areas, orchestra pits, and projection booths shall be in rigid metal conduit, armoured cable, lead-sheathed armoured cable, or aluminium-sheathed cable except that: a) other wiring methods shall be permitted for temporary work,and
b) flexible cord or cable shall be permitted in accordance with other Clauses in this Section.
(2) Surface raceways shall not be used on the stage side of the proscenium wall, (3) Wiring in areas other than those listed in (1) above shall be in accordance with the requirements of the appropriate Sections of this Code. (4) Circuits for aisle lights located under seats may supply 30 outlets provided that the size of lamp which can. be used with each outlet is limited by barriers or the equivalent to 25.0W or less.
388
EBCS-10 1995
ETHIOPIAN BUILDING CODE STANDARD
SECTION 19: THEATRE INSTALLATION
19.4
FIXED STAGE SWITCHBOARD
(1) Stage switchboard shall be: a) of the dead-front type, and b) protected above with a suitable metal guard or hood extending the full length of the board and completely covering the space between the wall and the board to protect the latter from falling objects. (2) Where a stage switchboard has exposed live parts on the back of the board, it shall be enclosed by the walls of the building, by wire mesh grills, or by other acceptable methods. (3) The entrance to the enclosures shall have a self-closing door. (4) Switches shall be of the enclosed type and externally operated. (5) Pilot lamp on switchboard shall be: (a) (b) (c)
installed within every switchboard enclosure, connected to the circuit supplying the ·switchboard so that the opening of the master switch does not cut off the supply to the lamp, and on an independent circuit protected by an overcurrent device rated or set at not more than 15.0A.
19.4.1 Fuses (1) Fuses on switchboards shall be:
a) of either the plug or cartridge type, and
b) provided with enclosures in addition to the switchboard enclosure.
19.4.2 Overcurrent Protection (1) All circuits leaving the switchboard shall have an overcurrent protection device connected in each unearthed conductor.
ETHIOPIAN BUILDING CODE STANDARD
EBCS-10 1995
389
ELECTRICALINSTAU.ATlbNOF :SUILD'ING$
19.4.3 Dimmers (I) Dimmersshall be connected so as to' be deadwhen their respectivecircuit switches ate open. (2) Dimmers which do not 'open the circuit maybeconnected :lh earthedneutralconductor. (3) The terminals Of dimmers 'shallbe enclosed, (4) Dimmer faceplates shall be arranged so thataccidentalcontactcannot readilybemadewith the faceplate contacts.
19.4.4 Control of Stage and Gallery Pockets (I) Stageandgallerypockets shall be controlled from the switchboard. 19;4.5 Conductors (1) Stage switchboardsequipped with resistive- ortransformed-type 'aimmerswit~hesshanbe wifed With conductors having insulationsuitable for the temperaturegenera:ted therein; 'bot in no case shall the design temperature 'be less than 125°C. (2) The conductors in (I) above shall have an ampacityof not less than that ofthe switch or overcurrent device to which they are connected. (3) Holes in the metal enclosure through which conductors pass shall be bushed. (4) Thestrands Of theconductor shall be soldered together before they ate fastenedundera clamporbinding screw. (5) Where a conductor of IO;Omm 2 or of a largersizeisconrrectedto a terminal: a) it shall be soldered into a lug, or b)a solderless connector shall be used.
390
ESCS-10 1995
ETHIOPIAN BUILDING CODE STANDARD
Sf;CTlQN 1~: THEATRE- !N$TALL,ATI,ON
19.5
J,?QRTi\BLE SWITCHBQARJ) ON
~TAGE
19.5.1 CQnstrll.ction of Portable Switchboards (1) Portable switchboards shall be placed within enclosure of substantial construction; but they may be arranged SO that the enclosure is open during, operation,
(2) There shall be no live parts exposed within the enclosure except those on dimmer faceplates, 19.5.2 Supply for Portable Swltehboard (1) Portable. switchboards shall be supplied by Il1eaJ;1S of flexible cord or cable of extra-hard usage type terminating within the switchboard enclosure in aJ;1 externally operated, enclosed, fused master switch.
(2) The. master switch in (1) above shall be arranged so as to cut off current from all apparatus within the enclosure except the pilot li~ht. (3) The flexible cord or cable shall have sufficient amapcity to carry the total load current of the switchboard. (4) The ampere-rating of the fuses of the master switch shall not be greater than the. total load current of the switchboard.
19.6
FIXED ST i\GE EQUIPMENT
19.(j.l Footlights (1) Where footlights are wired in rigid metal conduit or electrical metallic tubing, every lampholder shall be installed in an individual outlet box, (2) Where footlights are not wired in rigid metal conduit or electrical metallic tubing, the wiring shall be installed in a metal trough.
19;(i.2 Metalwork (I) The metalwork for footlights, borders, proscenium sidelights, and strips shall not be lesr than O.8mm thick.
ETHIOPIAN BUILDING CODE STANDARD
EBCS-10 1995
391
ELECTRICAL INSTALLATION OF BUIl.DINGS
(2) The metalwork for bunches and portable strips shall be not less than O.5mm thick.
19.6.3 Clearance at Terminals (1) The terminals of lampholders shall be separated from the "metal of the trough by at least 13.0mm.
19.6.4 Mechanical Protection (1) Borders, proscenium sidelights, and strips shall be constructed so that the flanges of the reflectors or other suitable guards protect the lamps from mechanical injury and from accidental contact with scenery or other combustible material.
19.6.5 Suspended Fixtures (l) Borders and strips shall be so suspended as to be electrically and mechanically safe.
19.6.6 Connections at Lampholders (1) Conductors shall be soldered to the terminals of lampholders unless other suitable means are providedto obtain positive and reliable connection under severe vibration.
19.6.7 Ventilation for Mogul Lampholers (1) Where the lighting device are equipped with mogullampholders, the lighting devices shall be constructed with double walls and with adequate ventilation between the walls.
19.6.8 Conductor Insulation for Field-Assembled Fixtures (I) Foot, border, proscenium, and portable striplight fixtures assembled in the field shall be wired with conductors having insulation suitable for the temperature at which the conductors will be operated; but in no case shall the design temperature be less than 125°C.
19.6.9 Branch Circuit Overcurrent Protection (1) Branch circuits for footlights, border lights, and proscenium sidelights shall have overcurrent protection in accordance with 15.3.1.4.
392
EBCS-10 1995
ETHIOPIAN BUILDING CODE STANDARD
SECTION 19: THEATRE INSTALLATION
19.6~10
Pendant Lights Rated More Than 100.0W
(1) Where, a pendent lighting device contains a lamp or group of lamps of more than lOO.OW capacity, it shall be provided with a guard of not more than 13.0mm mesh so arranged as to prevent damage from falling glass.
19.6.11 Cables for Border Lights (1) Flexible cord or cable for border lights shall be of extra-hard-usage type. (2) The flexible cord or cable shall be fed from points on the grid iron or from other acceptable overhead points; but they shall not be fed from side walls. (3) The flexible cord or cable shall be arranged so that strain is taken from clamps and binding screws. (4) Where the flexible cord or cable passes through a metal or wooden enclosure, a metal bushing shall be provided to protect the cord. (5) Terminals or binding posts to which flexible cords or cables are connected inside the switchboard enclosure shall be located so as to permit convenient access to them.
19.6.12
Wiring to Arc Pockets
(1) Where the wiring to arc pockets is in rigid metal conduit or electrical metallic tubing, the. end of the conduit or tubing shall be exposed at a point approximately 300.0mm away from the pocket, and the wiring shall be continued in flexible metal conduit in the form of a loop at least 600.0mm long, with sufficient slack to permit the raising or lowering of the box.
19.6.13
Socket Outlets and Plugs
(1) Socket outlets intended for the connection of arc lamps shall: a) have an ampere rating not less than 40.0A, and
b) be supplied by copper conductors not smaller than 16.0mm2 •
ETHIOPIAN BUILDING CODE STANDARD
EBCS-10 1995
393
ELECTRICAL INSTALLATION OF BUILDINGS
(2) Socket outlets intended for the connection of incandescent lamps shall: a) have an ampere rating not less than 16.0A, and
b) be supplied by conductors not smaller than 4.0mm2 copper or 6.0mm 2 aluminium.
(3) Plugs for arc and incandescent socket outlets shall not be interchangeable. 19~6.14
Curtain Motors
(1) Curtain motors shall be of the closed type.
19.6.15
Flue Damper Control
(1) Where stage flue dampers are released by an electrical device, the circuit operating the device shall, in normal operation, be closed. (2) The circuit shall be controlled by at least two single-pole switches enclosed in metal boxes with self-closing doors without locks or latches. (3) One switch shall be placed at the electrician's station and the other at a suitable place. (4) The device shall be: a) designed for the full voltage of the circuit to which it is connected, or resistance being inserted;
b) located in the loft above the scenery; and
c) enclosed in a suitable metal box with a tight self-closing door.
19.7
PORTABLE STAGE EQUIPMENT
19.7.1 Fixtures on Scenery (1) Fixtures attached to stage scenery shall be: a) of the internally wired type, or
b) wired with flexible cord or cable suitable for hard usage.
(2) The fixtures shall be secured firmly in place.
394
EBCS-10 1995
ETHIOPIAN BUILDING CODE STANDARD
SECTION 19: THEATRE INSTALLATION
(3) The stems of the fixtures shall be carried through to the back of the scenery and shall have a suitable bushing on the end thereof
19.7.2 String or Festooned Lights (1) Joints in the wiring of string or festooned lights shall be staggered where practicable. (2) Where the lamps of string or festooned lights are enclosed in paper lanterns, shades, or other devices of combustible material, they shall be equipped with lamp guards.
19.7.3 Flexible Conductors from Portable Equipment (1) Flexible conductors for arc lamps, bunches, or other portable equipment shall be of extra hard-usage type cord or cable; but for separate miscellaneous portable devices operated under conditions where the conductors are not exposed to severe mechanical injury, reinforced cords of ordinary type may be used provided that they are protected by an overcurrent device rated or set at not more than 16.0A.
19.7.4 Portable Equipment for Stage Effects (1) Portable equipment for stage effects shall be of a type acceptable for the purpose and shall be so located that flames, sparks, or hot particles cannot come in contact with combustible material.
ETHIOPIAN BUILDING CODE ,STANDARD
EBCS-10 1995
395
SECTION
20
EMERGENCY SYSTEMS, UNIT
EQUIPMENT, AND EXIT SIGNS
20.1
SCOPE
(l) This Section applies to:
a) the installation, operation and maintenance of emergency system and unit equipment intended to supply illumination and to emergency systems intended to supply power, where required by the authority having jurisdiction, and b) thewiring of exit signs.
20.2
NORMATIVE REFERENCE
(l) The following reference contains provisions which, through reference in this text, constitute provisions of the Ethiopian Building Code Standard on Electrical Installation of Buildings.
a) C22.1: 1990
20.3
Canadian Electrical Code, Part 1, Safety Standard for Electrical Installations, Sixteenth Edition.
GENERAL
20.3.1 Capacity (l) Emergency systems and unit equipment shall have adequate capacity and rating to ensure the satisfactory operation of all connected equipment when the general power supply fails.
396
EBCS-10 1995
ETHIOPIAN BUILDING CODE STANDARD
SECTION 20: EMERGENCY SYSTEMS, UNIT EQUIPMENT, AND EXIT SIGNS
20.3.2 Instruction (1) Complete instructions for the operation and maintenance of the emergency system or unit equipment which shall also specify testing at least once every month to ensure security of operation, shall be posted on the premises in a frame under glass.
20.3.3 Batteries Maintenance (1) When batteries are used as a source of supply, the batteries shall be kept:
a) in proper condition, and
b) fully charged at all times.
20.3.4 Lamps (1) Emergency lights shall be so arranged that the failure of one lamp will not leave the area normally illuminated by it in total darkness.
20.3.5 Circuits (1) No appliance or lamp, other than those required for emergency purposes, shall be supplied
by the emergency circuits. 20.3.6
Method of Wiring
20.3.6.1
General
(1) The method of wiring, including that between unit equipment and remote lamps, shall be in accordance with the provisions of Section 8.
20.3.6.2
Segregation
(1) The wiring shall be kept entirely independent of all other wiring and equipment and shall not enter a fixture, raceway, box, or cabinet occupied by other wiring except, where necessary: a) in transfer switch, and
b) in emergency lighting fixtures supplied from two sources.
ETHIOPIAN SOJ[DING CODE STANDARD
EBCS-10 1995
397
ELECTRICAL INSTALLATION OF BUlLDINGS
20.4
EMERGENCY SYSTEMS
20.4.1 Supply (l) The emergency supply shall be a standby supply consisting of;
a) a storage battery of the rechargeable type having sufficient capacity to supply and maintain the total load of the emergency circuits at not less than 91 % of the full voltage for the time period required by the authority having jurisdiction, but in no case less than Y2hr, and be equipped with a charging means to maintain the battery in a charged condition automatically. Note:
Automobile batteries and lead batteries not of the enclosed glass-jar type are not considered suitable.
b) a generator driven by a dependable prime mover and it shall be: i) of capacity sufficient to carry the load, and ii) arranged to start automatically without failure and without undue delay upon the failure of the current supply of the principal equipment of the building.
iO.4.2 Control (l) The current supply for emergency systems shall be controlled by an automatic transfer switch which energizes the emergency system upon failure of the normal current supply and is accessible only to authorized persons.
20.4.3 Overcurrent Protection (1) No device capable of interrupting the circuit, other than the overcurrent device for the current supply of the emergency system, shall be placed ahead of the branch circuit overcurrent
device.
20.4.4
Audible and Visual Trouble Signal Devices
20.4.4.1
Trouble signal
(l) Every emergency system shall be equipped with audible and visual trouble signal devices which give warning of derangement of the current source or sources and which indicate when the emergency load is supplied from batteries or generators.
398
EBCS-10 1995
ETHIOPIAN BUILDING CODE STANDARD
SECTION 20: EMERGENCY SYSTEMS, UNIT EQUlPMENT, AND EXIT SIGNS
20.4.4.2
'Wiring
(I) Audible trouble signals may be wired so that: a) they can be silenced, but a red-warning or trouble light shall continue to provide the protective function,and
b) when the system is restored to normal, the audible signal will:
i) sound, thus indicating the necessity of restoring the silencing switch to its normal position, or ii) reset automatically so as to sound for any subsequent operation .of the emergency system. 20.4~4.3
Voltage drop
(1) the voltage drop in the wiring feeding lamps mounted remotefrom thecurrent supply shall
not exceed 5% ofthe applied voltage.
2'0.5
UNITEQUIPMENT
20.5.1 Mounting (I ) Each unit equipment shall be mounted with the bottom of enclosure not less than 2;Om
above the float wherever practicable. Note:
Unit equipment for emergency lighting is definedasanitemofequipment that: i) is intended to.provide automatically, in response toa failure of a power supply to which it is connected,
specified light output and a specified amount ofpower forillumination purposes, for aspecifiedpeniod . of time, but in any case not less than 30.0min; Ii) comprises, in a unit construction, a storage battery, charging:meanstomaiIitainthebatteryin a charged condition automatically, lamps, Of outputterminals towhich specificallylisted lamps maybe connected, means to energize the lamps when the normal power supplyfailsandto de-energize the lamps when the normal power supply is restored, and means to indicate and test the operating conditions of the equipment.
ETHIOPIAN BUILDING CODE STANDARD
EBCS-10 1995
399
ELECTRICAL INSTALLATION OF BUILDI~GS
20.5.2
Supply Connections
20.5.2.1
Outlet distance
(1) Outlet point to which unit equipment is to be connected shall be not more than 1.5mfrom the location of the unit equipment.
20.5.2.2
Connection to supply
(1) Unit equipment shall be permanently connected to the supply if: a) the voltage rating exceeds 230.0V, or
b) the marked input rating exceeds 24.0A.
(2) Where the above ratings are not exceeded, the unit equipment may be connected using the flexible cord and attachment plug supplied with the equipment.
20.5.2.3
Installation
(1) Unit equipment shall be installed in such a manner that it will be automatically actuated upon the failure of the power supply to the normal lighting in the area covered by that unit
equipment.
20.5.2.4
Feeding
(1) Unit equipment shall be fed, where practicable, from the same panel board, and may be fed from the same branch circuit which feeds the normal lighting in the area covered by that unit
equipment.
20.5.2.5
Voltage drop
(1) The circuit conductors to lamps mounted remote from supply SOUrce shall be of such size that the voltage drop does not exceed 5% of the marked output voltage of the unit equipment.
20.5.1.6
Excess load
(1) The number of lamps connected to single equipment shall not result in a load that is in
excess of the
watt output rating marked on the equipment for the required emergency period. '.
400
EBCS-10 1995
ETHIOPIAN BUILDING CODE STANDARD
SECTION 20: EMERGENCY SYSTEMS, UNIT EQUIPMENT, AND EXIT SIGNS
20.6
EXIT SIGNS·
20.6.1 Power Supply (1) The power supply for exit signs shall be provided from:
a) a separate circuit or circuits used for no other purpose, or
b) the circuit supplying exit lighting
20.6.2 Wiring (1) Exit signs shall be wired in accordance with the provisions of Section 8 of this Code.
-...
ETHIOPIAN BUILDING CODE STANDARD
EBCS-10 1995
401
..
~'
SECTION
21
MOTION PICTURE STUDIOS, PROJECTION
ROOMS, FILM EXCHANGES AND FACTORIES
21.1
SCOPE
(1) This Section sets provisions and installation requirements that apply to motion-picture studios, projection rooms,exchanges, factories and any building in which motion-picture films, pyroxylin plastic and nitrocellulose x-ray and photographic films are manufactured, projected,developed, printed, rewound, repaired or stored. 21.2
NORMATIVE REFERENCES
(1) The followingreferencescontain provisions which,through reference in this text, constitute provisions of the Ethiopian Building Code Standard on Electrical Installation of Buildings:
a) C22.1:1990
Canadian Electrical Code, Part 1, Safety Standard for Electrical Installations, Sixteenth Edition.
b) NFPA70/NEC:1986
National Fire Protection Association I American National Electrical Code, 1987 Edition
21.3
GENERAL
21.3.1 Wiring Method (1) The wiring-method.unless specified otherwise in subc1auseofthisSection, shall be rigid conduit, steel electrical metallic tubing, or mineral-insulated cable. -(2) The wiring for stage-set lighting, stage effects, electric equipment used as stage properties, and other wiring not fixed as to location, shall be done with approved flexible cords and cables.
402
EBCS-tO 1995
ETHIOPIAN BUILDING CODE STANDARD
SECTION 21: MOTION PICTURE STUDIOS, PROJECTION ROOMS, ETC
(3) For portable lamps other than those used as properties in a motion-picture set on a studio stage or similar location, the lamp holders shall be: a) unswitched,
b) of composition or metal sheathed procelain, and
c) provided with a guard hook and handle.
21.4
VIEWING, CUTTING AND PATCIllNG TABLE FIXTURE
(1) All lighting fixtures, except lamps forming an integral part of table equipment, shall be of the totally-enclosed gasketted type. 21.5
FILM VAULTS AND STORAGE ROOMS
21.5.1 Equipment in Film Vaults and Storage Rooms (1) In rooms used for storage of pyroxylin plastic, no socket outlet or attachment plugs shall be installed. (2) .No electrical equipment other than that necessary for fixed lighting shall be installed in film vaults. 21.5.2 Wiring Method in Film Vaults (1) The wiring method in film-vault.shall be rigid-conduit or mineral-insulated cable only, with threaded joints at couplings boxes and fittings. (2) Conduit or cable shall not run directly from vault to vault, but only form the switch to the lighting fixture within the vault. (3) Conduit shall be sealed off near the switch enclosure with a fitting and compound approved for the purpose. 21.5.3 Lighting Fixtures in Film Vaults (1) Lighting fixtures in film vaults shall be of the explosion-proof type approved for the use in Class I Group C hazardous locations and shall have metal cages or guards protecting the globs.
ETHIOPIAN BUILDING CODE STANDARD
EBCS-10 1995
403
ELECTRICAL INSTALLATION OF BUILDINGS
(2) The fixtures in (1) above shall be located as close as practicable to the ceiling to avoid their being damaged through handling of film containers. 21.5.4 Film Vault Circuits (1) Fixtures shall be controlled by a double pole switch located outside the film vault. (2) A red pilot light shall be provided to indicate when the switch is closed and shall be located outside the film vault. (3) Wiring shall be arranged so that, when the switch is off, all conductors within the film vault will be dead. 21.6
MOTION PICTURE PROJECTION ROOMS
21.6.1 Lamps in Projection Rooms (1) Incandescent lamps in projection rooms or booths shall be provided with a lamp guard unless otherwise protected by noncombustible shades or other enclosures. 21.6.2 Arc Lamp Current Supply (1) Motor generator sets, frequency changers, transformers, rectifiers, rheostats, and similar equipment for the supply or control of current to arc lamps or projectors shall be located in a room separate from the projection room. 21.6.3 Ventilation (1) Exhaust ventilation fans for the projection room shall be controlled from inside the projection room. 21.7
MOTORS AND GENERATORS
(1) Motors and generators having brushes or sliding contacts, other than those used on studio stages or those installed in accordance with Clause 21.6.2, shall be of approved dust tight or enclosed types.
404
EBCS-10 1995
ETHIOPIAN BUILDING CODE STANDARD
SECTION
22
DIAGNOSTIC IMAGING INSTALLATION
22.1
SCOPE
(1) This Section of the Code applies to the installation of x-ray and other diagnostic imaging equipment operating at any frequency. However, it does not specify safeguards against direct, stray, or secondary radiation emitted by the equipment.
22.2
NORMATIVE REFERENCES
(1) The following references contain provisions which, through reference in this text, constitute provisions of the Ethiopian Building Code Standard on Electrical Installation of Buildings: a) C22.1: 1990
Canadian Electrical Code, Part 1, Safety Standard for Electrical Installations, Sixteenth Edition.
b) NFPA70INEC:1986
National Fire Protection Association/American National Electrical Code, 1987 Edition.
22.3
DEFINITIONS
(1) For the purpose of this Section, in addition to the tenns defined in Section 1, the following definitions shall apply when referring to x-ray or,computerized tomography equipment,
longutlme rating
a rating that is applicable for an operating period of'S.Omin or more.
momentary rating
a rating that is applicable for an operating period of not more than 20.0s.
ETHIOPIAN BUILDIN'G CODE STANDARD
EBC.S-10 1995
405
ELECTRICAL INSTALLATION OF BUILDINGS
22.4
mGH-VOLTAGE GUARDING
(1) High-voltage parts shall be mounted within metal enclosures that are bondedto earth except when installed in separate rooms or enclosures where a suitable switch shall be: a) provided to control the circuit supplying diagnostic imaging equipment, and b) arranged so that it will be in an open position except when the door of the room or enclosure is locked. (2) High voltage parts of diagnostic imaging equipment shall be insulated from the enclosure. (3) Conductors in the high voltage circuits shall be of the shock-proof type. (4) A milliammetre, if provided, shall be: a) connected, if practicable, in the lead that is bonded to earth.,or b) guarded if connected in the high voltage lead.
22.5·
CONNECTIONS TO SUPPLY ClkCUIT
(1) Permanently connected diagnostic imaging equipment shall be connected to the power source by means of a wiring method meeting the general requirements of this Code except that equipment properly supplied by a branch circuit rated at not over 30.0A shall be permitted to be supplied through a suitable attachment plug and hard-service cable or cord.
(2) Mobile diagnostic imaging equipment of any capacity may be connected to its power source by .suitable temporary connections and hard-usage cable or cord.
22.6
DISCONNECTING MEANS
_(1) A disconnecting means of adequate capacity for at-least 50% of the input required for the momentary rating or 100% of the input required. for the long-time rating of. x-ray or: computerized tomography equipment, whichever is greater, shall be provided in the supply circuit in a location readily accessible from the radiation control.
406
ESC5-10 1995
ETHIOPIAN BUILDING CODE STANDARD
SECTION 22: DIAGNOSTIC IMAGING INSTALLATION
22.7
TRANSFORMERS AND CAPACITORS
(1) Capacitors forming part of a diagnostic Imaging equipment shall be provided with an automatic means for discharging and grounding the plates whenever the transformer primary is disconnected from the source of supply unless all current-carrying parts of the capacitors and of the conductors connected therewith are: a) at least 2.5m from the floor and are inaccessible to unauthorized persons, or b) within metal enclosures that are bonded to earth or within enclosures of insulating material if within 25m of the floor.
22.8
CONTROL
(1) For stationary equipment, the low-voltage circuit of the step-up transformer shall contain an overcurrent device which:
a) has no exposed live parts, b) protects the radiographic circuit against fault conditions under all operating conditions, and c) is installed as part of the equipment or adjacent thereto. (2) Where as in (1) above, the design of the step-up transformer is such ~at branch fuses having a current rating lower than that of the overcurrent device are required for adequate protection for fluoroscopic and therapeutic circuits, they shall be added for the protection of these circuits. (3) For portable equipment, the requirements of (1) and (2) above shall apply; but, the overcurrent device shall be located in or on the equipment except that no current-limiting device is required when the high-voltage parts are within a single metal enclosure that is provided with a means for bonding to earth. (4) Where more than one piece of equipment is operated' from the same high-voltage circuit, each piece or group of equipment, as a unit, shall be provided with a high-voltage switch or equivalent disconnecting means.
ETHIOPIAN BUILDING CODE STANDARD
EBCS-10 1995
407
ELECTRlCAL INSTALLATION OF BUILDINGS
·22.9
AMPACITY OF PROTECTION
SUPPLY CONDUcrORS
AND RATING OF
OVERCURRENT
(1) The ampacity of supply conductors and the rating of overcurrent protection devices shall not be less than:
a) the long-time current rating of x-ray or computerized tomography equipment, or b) 50% of the maximum momentary current rating required by x-ray or computerized tomography equipment on a radiographic setting. (2) Theampacity of conductors and the rating of overcurrent protection devices for two or more branch circuits supplying x-ray or computerized tomography units shall not be less than: a) the sum of the long-time current rating of all x-ray or computerized tomography units which are intended to be operated at anyone time, or b) the sum of 50% the maximum momentary current rating for x-ray or .computerized tomography equipment on a radiographic setting for the two largest units plus 20% of the maximum current rating of the other units. 22.10 .BONDING
(1) Non-current-carrying parts of tube stands, tables and othes apparatus shall be bonded to earth in accordance with the requirements of Part I, -Section 7 of this Code.
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408
EBCS-10 1995
ETHIOPIAN BUILDING CODE STANDARD
SECTION
23
ELECTRICAL COMMUNICATION SYSTEMS
23.1
SCOPE
(1) This Section applies to the installation of electrical communication systems including information processing systems.
23.2
NORMATIVE REFERENCE
(1) The following reference contains provisions which, through reference In this text, constitute provisions of the Ethiopian Building Code Standard on Electrical Installation of Buildings: a) C221: 1990
23.3
Canadian Electrical Code Part 1, Safety Standard for Electrical Installations, Sixteenth: Edition.
GENERAL
23.3.1 Circuits in Communication Cables (1) Radio and television circuits, r;emote control circuits, fire alarm circuits, or parts thereof shall be:
a) permitted to use conductors in a cable assembly of communication building entrance having other conductors used as communication circuits, b) deemed to be communication circuits within the portions of circuits that use conductors within the communication building entrance cable assembly, and c) suitably protected at the point of interface connection with the communication cable conductors.
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23.3.2 Hazardous Locations (1) Where the wiring orelectrical equipment within the scope of this Section is installed in hazardous locations as defmed in Sections 11, 12, or 14, it shall also comply with the applicable Clauses of those Sections.
23.3.3 Approved Transformers . .(1) Where transformers or other devices supply current to a communication circuit. from an> electric supply circuit, the transfomiers or other devices shall be of a type approved for the service.
23.4
INSIDE CONDUCTORS
23.4.1. Conductors Arrangement (1) Conductors shall be neatly arranged and'secured in place in aconvenient and workmanlike . . manner.
. (2) Raceways for communication circuits'shall be installed in accordance with the requirements of Section 10 and, in case of metal, they shall be earthed in accordance with the provisions of . Section 7.
23.4.2 Insulation (1) Wire and cable used for communication system in a building shall be of the approved types as specified in Annex B, Section 4 of this Standard.
; 23.4.3 Earthing Conductors with an Outer Metal Covering (1) Where a conductor or cable is equipped with an outer metal covering, the covering shall be earthed.
23.4.4 Separation from Other Conductors (1) The conductors of an electrical communication system in buildings shall be separated at least
. SO.Omm from any insulated conductor of a Class 1 circuit or an electric light or power system
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operating at 380.0V or less, and shall be separated at least 600.0mm from any insulated conductor or an electric light or power system operating at more than 380.0V unless: a) one system is in earthed metal raceways, metal sheathed cable, or earthed armoured cable, 'b) the Class 1 circuit or electric light or power system operating at 380.0V or less utilizes a nonmetallic sheathed cable or hard-usage or extra-hard-usage flexible cord, or c) both systems are permanently separated by a continuous, firmly fixed non-meta! raceway in addition to the insulation of the conductors. (2) Where the light or power conductors are bare, all communication conductors in the same room or space shall be enclosed in an earthed metal raceway and. no opening, such as an outlet box, may be located within 2.0m of bare conductors of up to and including 15.0kV or.within / 3.0m of bare conductors above 15.0kV. (3) The conductors of an electrical communication system shall not be placed in any outlet box, junction box, raceway, or similar fitting or compartment which contains conductors of electric light or power systems or of Class 1 circuits (as defined in Section 10) unless: a) the communication conductors are separated from the other conductors by an acceptable partition, or b) the power or Class 1 conductors are placed solely for the purpose of supplying power to the communication system, or for connection to remote control equipment. (4) The conductors of an electrical communication system in a building shall not be placed in a shaft with the conductors of an electric light or power system unless: a) the conductors of all systems are insulated and are separated by at least 50.0mm, or b) the conductors of either system are encased in noncombustible tubing.
23.4.5 Penetration of a Fire Separation (1) Conductors of communication circuits extending through a fire separation shall be installed so as to limit the spread of fire.
23.4.6 Communication Cable in Hoistways (1) Special permission shall be required to install communication conductors in hoistways.
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(2) All conductors, except travelling cables, shall be totally enclosed in continuous metal raceway. (3) Pullboxes required for communication interconnection shall be located outside the hoistway. 23.4.7 Communication Conductors in Ducts and Plenum Chambers (1) .Communication conductors shall not be placed in ducts or plenum chambers except as permitted by relevant Clauses of Section 8. 23.4.8 Data Processing Systems (1) The interconnecting' cables used in data processing systems shall be permitted to contain power and communication conductors where such cables are specifically approved for the purpose.
23.4.9 Conductors under Raised Floors (1) Conductors or communication circuits shall be allowed to be installed, without additional mechanical protection, under a raised floor provided that: a) the raised floor is of suitable noncombustible construction; b) at least a 50.0mm separation is provided and maintained where the conductors are used to serve data processing systems and are placed parallel to any other power supply wiring; and c) the conductors serve the equipment located only on the floor above the raised floor, . where the space under the raised floor is used as an air plenum. 23.4.10
Conductors in Concealed Installations
(1) Where the ends of cables or conductors are not terminated on a device, they shall be capped or taped.
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23.4.11
Type CFC Under-Carpet Wiring System
23.4.11.1 General (l) The provisions of Clause 23.4.11 apply to the installation of communication flat-cable-type (CFC) systems which, together with the connecting devices, shall be approved or acceptable for the purpose.
23.4.11.2 Use permitted (1) Type CFC system wiring shall be permitted to be used: a) only under carpet squares not exceeding 750.0mm, and any adhesive used shall be of release type; b) as an extension of conventional wiring to serve areas or zones, and each run of wiring from the transition point shall not exceed 15.0m; c) on hard, smooth, continuous floor surface made of concrete if sealed, ceramic or composition flooring, wood, or similar material; . d) in dry or interior damp locations;
e) on floors heated in excess of 30°C only, if approved and identified for that purpose.
23.4.11.3 Use prohibited (l) Type CFC system wiring shall not be used:
a) b) c) d) e)
outdoors or in wet locations;
where subject to corrosive vapours or liquids;
in hazardous locations;
in dwelling units;
in hospitals or institutional buildings except in office areas;
f) on walls except when entering the transition point;
g) under permanent type partitions or walls.
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23.4.11.4 Floor protective coverings (l) Type CFC system wiring shall be covered with abrasion resistant tape, secured to the floor so as to completely cover all cables, comers, and bare conductor ends.
23.4.11.5 Coverings (l) Type CFC system wiring shall be permitted to cross over or under each other, and over or under power supply system wiring provided there is a layer of earthed metal shielding between the CFC and the power supply system cables.
23.4.11.6 System height (l) Type CFC system wiring shall not be stacked on top of each other except as required to enter the transition point.
23.4.11.7 Earthing of shields (1) Type CFC system wiring equipped with.a metal shield shall be earthed.'
23.5
EQUIPMENT
23.5.1 Communication Equipment in Bathrooms (1) Communication equipment located in a bathroom shall be permanently fixed on the wall, and shall be located so that no part may be reached or used from the bath or from the shower enclosure; however, it shall be permitted to be actuated by means of a cord with an insulating link. , (2) Communication jacks shall not be located in a bathroom.
23.5.2 Equipment in Air Ducts, Plenums, or Suspended Ceilings (1) Communication equipment and terminals shall not be placed in ducts, plenums, or hollow spaces which are used to transport air nor in suspended ceiling areas except where a duct, plenum, or hollow space is created by a suspended ceiling having lay-in panels or tiles; connecting blocks which are a non-protective type may be installed provided they are placed in an accessible enclosure.
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23.5.3 Exposed Equipment and Terminations (1) Exposed communication equipment and/or associated terminations shall be located in a suitable room separate from electrical ·light or power installations, except where necessary to place them in a joint-use room in which case a minimum separation of900.0mm from electrical equipment requiring adjustment and maintenance shall be provided and maintained.
23.5.4 Earth Circuits (l) Communication circuits connected to a telecommunication network and having return path via local earth or other circuitry which similarly could present a fire hazard, shall be provided with a current-limiting device installed in or adjacent to the equipment of a type recommended by the equipment manufacturer as suitable for the application, which will limit the current under normal operating conditions and under fault conditions, to prevent fire hazards.
23.5.5 Communication Systems in Hospitals (1) Exposed non-current-carrying metal parts, if they could become. energized, of communications equipment, other than telephone sets, installed in general, intermediate, and critical care areas. of hospitals shall be earthed to conform with the requirements of Clause 14.4.2(5).
23.6
OUTSIDE· CONDUCTORS
23.6.1 Overhead Conductors on Poles (1) The installation of overhead communication conductors on poles in proximity with power conductors shall be established in conformity with the rules and regulations of the Ethiopian Electric Light & Power Authority (EELPA).
23.6.2 Overhead Conductors on Roofs (I) Communication conductors passing over buildings shall be kept at least 205m above any roof which may readily be walked upon. (2) Communication conductors shall not be attached to the upper surfaces of roofs or be run .within 2.0m, measured vertically, of a roof without special permission.
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23.6.3 Lightning Conductors (1) Separation of at least 2.0m shall, where practicabl~, be maintained between conductors of communication circuits on buildings and lightning conductors.
23.6.4 Swimming Pools (1) Where wires or cables are installed over or adjacent to swimming pools, they shall be paced in accordance with the provisions of Clauses 25.4.2 and 25.4.3 of Section 25.
23.7
UNDERGROUND CIRCUITS
23.7.1 Direct Buried Systems (1) Where communication conductors or cable assemblies are direct buried, the sheath shall be suitable for direct burial and the conductor or cable assembly shall: a) not be installed in the same vertical plane with other underground systems, except when installed in accordance with (g) below; b) maintain a minimum horizontal separation of 300.0mm from other underground systems, except when installed in accordance with (g) below; c) not be less than 600.0mm deep, unless rock bottom is encountered at a shallower depth in which case a minimum depth of 4S0.0mm shall be permitted, except that for service wire under parkways and lawns, the depth may be reduced to 4S0.0mm; d) be placed with a layer of sand 7S.0mm deep, both above and below the cable, if in rocky or stony ground; e) not be less than 900,Omm deep under an area which is subject to vehicular traffic, except that the depth may be reduced to 600,Omm when mechanical protection is provided, . which shall consist of: i) treated plank at least 38.0mm thick or other acceptable material which shall be placed over the conductor or cable after first backfilling with 7S.0mm of sand or earth containing no rocks or stones, or ii) a conduit suitable for earth burial placed to facilitate cable replacement and to minimize traffic vibration damage;
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f) not be placed in a common trench involving random separation with power supply cables
or wires operating at over 750.0V; and g) have a metal sheath when placed in a common trench involving random separation with power supply cables or wiring operating at 750.0V or less, in which case the communication conductor or cable assembly shall not cross under the supply cables,
23.7.2 Underground Raceway (1) Where communication conductors or cable assemblies are placed in underground raceway systems: a) the raceway, including laterals, shall be separated from those used forthe electric power system by not less than 50.0mm of concrete or 300.0mm of well-tamped earth; b) the raceway shall be located to maintain minimum depth of 600.0mm in areas subject to vehicular traffic and, 450.0mm in all other areas, except that where rock bottom is encountered at a shallower depth, the raceway shall be encased in concrete; c) the raceway shall not terminate in the same .manhole, and the conductors or cable assembly shall not be placed in the same manhole used for electric power system; d) the cables shall not be placed in the same raceway containing electric lighting or power supply cables; and e) the cable sheath shall be suitable for wet locations.
23.8
EARTHING
23.8.1Bon~ing
of Cable Sheath
(1) Where cables, either overhead or underground, enter buildings, the metal sheath or shield of the cable shall be bonded to earth as close as practicable to the point of entrance or shall be interrupted as close as practicable to the point of entrance by an insulating joint or equivalent device.
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23.8.2 Cable-Sheath Bonding Conductor (1) The cable-sheath bonding conductor required by Clause 23.8.1 shall have an ampacity equal to or greater than that of the outer conductive sheath of the exposed cable except that the bonding conductor shall not be required to be larger than 10.0mm 2 copper. 23.8.3 Earthing Electrode (1) Earthing conductor shall preferably be connected to a water-pipe earthing electrode as close to the point entrance as possible.
of
(2) Where waterpipe is not readily available and the earthing conductor of the power consumer's service is connected to the water pipe at the building, the communication system earthing conductor may be connected to the metal conduit, service equipment enclosures, or to . . . the earthing conductor of the power consumer's service. \
a
(3) In the absence of waterpipe, the communication earthing conductor may be connected to an effectively earthed metal structure or toan earth rod or pipe driven into. permanently damp earth; but: a) steam, gas, or hot water pipes or lightning rod conductors shall not be used as earthing electrodes; and b) a driven rod or. pipe used for earthing power circuits shall not be used as a: communication earthing electrode unless it is connected to the earthed conductor of a multi-earthed power neutral. (4) Where a driven earth rod or pipe is used as an earthing electrode for an electrical communication· system, it shall be separated by at least 2.0m from any other electrodes, including those used for power circuits, radio, lightning rods, or for any other purpose and shall be bonded only to that of the power circuits in accordance with applicable Clauses of Section 7. (5) The nonnallength of driven earth rod used as the earthing electrode for a communication system is 15m; but, where the normal rod would not reach moist soil when installed, a rod of suitable additional length shall be used.
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23.8.4 Earthing Electrode Connection (1) The earthing conductor shall be attached to an earthing electrode by means of an approved bolt clamp except that, in the case of an earth rod, a wire lead may be permanently connected to the rod. _(2) Where a bolt clamp is used, the earthing conductor shall be soldered or otherwise acceptably connected to the clamp in an effective manner. 23.8.5 Bonding of Electrodes (l) A copper conductor not smaller than 10.0mm2 shall be connected between communication and power earthing electrodes when separate artificial earthing electrodes are required as described per Clause 23.8.3.
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SECTION
24
COMMUNITY ANTENNA INSTALLATION FOR RADIO AND TELEVISION RECEPTION
24.1.
SCOPE
(l) This Section applies to the installation of:
a) community antenna assembly, b) head station (amplifier and other power sources), and c) distribution network (conductors, branching boxes and antenna or feeder outlets).
24.2
NORMATIVE REFERENCES
(l) The following references contain provisions which, through reference in this text, constitute provisions of the Ethiopian Building Code Standard on Electrical Installation of Buildings:
a) C22.1:1990
.Canadian electrical Code, Part 1, Safety Standard for Electrical Installations, Sixteenth Edition.
b) IEC 597
Aerials for the Reception of Sound and Television Broadcasting in the Frequency Range 30.0MHZ to 1.0GHZ:
i) Part 1-1977, Electrical and mechanical characteristics. ii) Part 2-1977 Methods of measurement of electrical performance parameters. . iii) Part 3-1983 Methods of measurement of mechanical properties, vibration and environmental tests. iv) Part 4-1984 Guide for the preparation ofaerial performance specification, detailed specification sheet format.
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c) IEC 728: 1982
24.3
Cabled Distribution System Primarily Intended for Sound and Television Signals Operating between 30.0MHz and I.OGHz.
TECHNICAL REQUIREMENTS
24.3.1 Mechanical (I) A community antenna shall comply with- all mechanical properties or requirements outlined
in the IEC 597 and IEC 728. 24.3.2 Electrical (I) A community antenna shall:
a) be designed for the reception of signals within the permitted bandwidth for sound and television broadcasting; b) be immune to extraneous signal interference; and c) comply with all ether necessary electrical parameters that are required for the satisfactory operation of the system (see IEC 597 and IEC 728).
24.4
EQUIPMENT
24.4.1 Community Antenna Distribution Amplifiers and Other Power Sources (l) Amplifiers and other devices which supply current to a community antenna distribution circuit from an electric supply circuit shall be approved for the purpose.
(2) Where amplifiers and other power devices are connected to an electric supply circuit and enclosed in a cabinet, the cabinet shall be so .located as to be readily accessible and shall be adequately ventilated. (3) The chassis and cabinets of the community antenna distribution amplifier or other power sources, the outer conductive shield of the coaxial cables, and the metal conduit or the metal cable sheath enclosing the electric supply conductors shall all be connected to the system earth with a minimum of 16.0m2 copper conductor.
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(4) Where a cabinet containing an amplifier or other power device is mounted accessible to the public, it shall be provided with a lock or similar closing device.
24.4.2 Exposed Equipment and Terminations (1) Exposed community antenna distribution equipment and/or associated terminations shall be located in a suitable room or similar area, separate from electrical light or power installations, except where necessary to place them in a joint-usc room in which case a minimum separation of 900.0mm from electrical equipment requiring adjustment and maintenance shall be provided and maintained.
24.4.3 Equipment Earthing (1) Non-powered equipment and enclosures or equipment powered exclusively hy the coaxial cable shall be considered earthed when they are effectively connected to the earthed outer conductive coaxial cable shield.
24.5
COMMUNITY ANTENNA DISTRIBUTION NETWORK
24.5.1 Conductor (1) The conductors used in the distribution network shall consist of coaxial cable having inner conductor and an outer conductive shield of circular cross-section.' (2) Conductors placed within buildings shall be of the approved types as specified in Annex B, Section 4, of this Code. (3) Conductors placed outside of buildings shall be of the types that are acceptable for the application.
24.5.2 Voltage Limitation (1) The coaxial cable shall be permitted to deliver low energy power to equipment directly associated with the community antenna distribution circuits if the voltage is not over 60.0V and if the current supply is from an approved amplifier, transformer, or other device having energy limiting characteristics.
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24.5.3 Hazardous Locations
(1) Where the circuits or equipment within the scope of this Section are installed in hazardous locations, they shalt also comply with the applicable Clauses of Sections 12, 13 and 14. 24.5.4 Supports (l) Where conductors are attached to or supported on buildings, the attachment or supporting
fixtures shall be acceptable for the purpose. 24.5.5 Earthing of Outer Conductive Shield of a Coaxial Cable (l) Where coaxial cable is exposed to lightning or to accidental contact with lightning arrester
conductors or power conductors operating at voltage exceeding 380.0V-to-earth, the outer conductive shield of the coaxial cable shall be earthed at the building as close to the point of cable entry as possible. (2) Where the outer conductive shield of a coaxial cable is earthed, no other protective device shall be required. (3) Earthing of a coaxial cable shield by means of a protective device shall be permitted provided that the device does not interrupt the earthing system within the building. 24.5.6 Earthing Conductor (l) The earthing conductor for the outer conductive shield of a coaxial cable shall have rubber
insulation not less than O.8mm in thickness, and shall be covered by a substantial fibrous covering except that conductors acceptable for the purpose, having less than O.8mm rubber insulation, or having other kinds of insulation, may be used. (2) The earthing conductor shall be of copper. (3) The earthing conductors shall be not smaller than 2.5mm2 • (4) The earthing conductor shall have an ampacity equal to or greater than that of the outer conductive sheath of the exposed coaxial cable.
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(5) Where two or more coaxial cables, which have outer conductive shields differing in size and ampacity, join at a common connection to the earthing conductor, the ampacity of the earthing conductor shall be equal to or exceed the ampacity of the largest coaxial outer conductive shield. (6) The earthing conductor shall be fun from the coaxial cable shield to the earthing electrode in as straight a line as possible. (7) The earthing conductor shall be protected in situations where it is or can be exposed to mechanical damage. 24.5.7 Earthing Electrode (1) Earthing electrodes shall conform to the requirements of relevant Clauses of Section 7.
(2) Where artificial earthing electrodes are installed, they shall be in accordance with applicable Clauses of Section 7 except that the minimum driven length of the rod electrode shall be 2.0m. (3) Artificial earthing electrodes for community antenna distribution shall be spaced and bonded with other electrodes in accordance with relevant Clause of Section 7. 24.5.8 Earthing Electrode Connection (1) The earthing conductor shall be attached to an earthing electrode by means ofan approved earth clamp except, in the case of an earth rod, a wire lead may be permanently connected to the rod and the wire lead connected to the earthing conductor by means of pressure connector or other acceptable means.
(2) Where an earth clamp is used, the earthing conductor shall be acceptably connected to the clamp in an effective manner. 24.6
CONDUCTORS WITHIN BUILDINGS
24.6.1 Separation from Other Conductors (1) Conductors of community antenna distribution circuits shall be separated at least 50.0mm from insulated conductors of electric lighting, power, or Class 1 circuits operating at 380.0V or less, and shall be separated at least 600.0mm from any insulated conductor of an electric
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lighting, power, or Class 1 circuit operating at more than 380.0V unless effective separation is afforded by use of: a) earthing metal raceways for the community antenna distribution circuits, or for the electric lighting, power and Class 1 circuits, b) earthed metal sheathed or armoured cable for the electric lighting, power, and Class 1 conductors, c) nonmetallic sheathed cable for the electric lighting, power, and Class 1 circuits operating at 380.0V or less, or d) raceways of a non-metal type as permitted in Section 8 in addition to the insulation on the community antenna distribution circuit conductors, or the electric lighting power, and Class 1 circuit conductors. (2) Where the electric lighting or power conductors are bare, all community antenna distribution conductors in the same room or space shall be enclosed in an earthed metal raceway and no opening, such as an outlet box, shall be located within 2.0m 'of bare conductors of up to and including 15.0kV or within 3.0m of bare conductors above 15.0kV. (3) The conductors of a community antenna- distribution circuit shall not be placed in any raceway, compartment, outlet box, junction box, or similar fitting which contains conductors of electric light, power, or Class 1 circuit unless: a) the conductors of the community antenna distribution circuit are separated from the electric light, power, or Class 1 circuit conductors by an acceptable barrier, or b) the power or Class 1 conductors .are placed solely for the purpose of supplying power to the community antenna distribution circuit.
24.6.2 Conductors in a Vertical Shaft (1) Conductors of a community antenna distribution circuit in a vertical shaft shall be in a totally enclosed noncombustible raceway.
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24.6.3 Penetration of a Fire Separation (l) Conductors of a community antenna distribution circuit extending through fire separation shall be so installed as to limit fire spread. 24.6.4 .Community Antenna Distribution Conductors in Ducts and. Plenum Chambers (1) Community antenna distribution conductors shall not be placed in ducts or plenum chambers except as permitted by relevant Clauses of Section 2 and Section 8 of this Code. 24.6.5 Raceways (1) Raceways shall be installed in accordance with the requirements of Section 8. 24.7
CONDUCTORS OUTSIDE OF BUILDINGS
24.7.1 Overhead Conductors on Poles (1) The installation of overhead community antenna distribution conductors in proximity with power conductors on poles and in aerial spans between buildings, poles, and other structures shall be established in conformity with rules and regulations of EELPA . 24.7.2 Overhead Conductors on Roofs (l) Community antenna distribution conductors 'passing over buildings shall be kept at least 2.5m above any roof which may be readily walked upon. (2) Community antenna distribution conductors shall not be attached to the upper surfaces of roofs or be run within 2.5m, measured vertically, of a roof without special permission. 24.7.3 Conductors on Buildings (l) Community antenna distribution conductors on buildings shall be separated from insulated light or power conductors not in cable or conduit by at least 300.0mm unless, in addition to the insulation on the conductors, they are permanently separated by a continuous and firmly fixed non-metal type raceway as permitted in Section 8 .
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(2) Community antenna distribution conductors subject to accidental contact with light or power conductors operating at voltages exceeding 380.0V and attached exposed to buildings shall be separated from combustible material by being supported on glass, porcelain, or other insulating material acceptable for the purpose, except that such separation is not required where the outer conductive sheath of the coaxial cable is earthed. (3) Community antenna distribution conductors attached to buildings shall not conflict with other communication conductors attached to the. same building and sufficient clearance shall be provided so that there will not be unnecessary interference to maintenance operations; and in no case should the conductors, strand, or equipment of one system cause abrasion to the conductors, strand, or equipment of the other system.
24.7.4 Conductors Entering Buildings (1) The community antenna distribution conductors shall enter the building either through a noncombustible, non-absorptive insulating bushing or through a metal raceway except that the insulating bushing or raceway may be omitted where" the"entering conductors pass through masonry or are acceptable for the purpose. 24.7.5 Swimming Pools
(1) Where conductors are installed over or adjacent to swimming pools, they shall be placed in accordance with the provisions of Clauses 25.4.2 and 25.4.3, Section 25 of this Code.
24.8
UNDERGROUND CONDUCTORS
24.8.1 Direct Buried Systems (1) Where community antenna distribution conductors are direct buried, the sheath shall be suitable for direct burial and the conductor shall be: a) installed outside of the same vertical plane which contains differing underground conductors other than communication conductors, except when installed in accordance with (f) below; b) maimtained at a minimum horizontal separation of 300.0mm from differing underground conductors other than communication conductors, except when installed in accordance with paragraph (f) below; I" ;
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c) placed at a minimum depth of 600.0mm, unless rock bottom is encountered at a shallower depth, in which case a minimum depth of 450.0mm shall be permitted, except that for service wires under parkways and lawns, the depth may be reduced to 450.0mm; d) placed with a layer of sand 75.0mm deep, both above and below the cable, if in rocky or stony ground; e) placed at a minimum depth of 900.0mm under an area which is subject to vehicular traffic, except that the depth may be reduced to 600.0mm when mechanical protection is provided which shall consist of: i) treated plank at least 38.0mm thick or other acceptable material which Shall be placed over the conductor or cable after first back-filling with 75.0mm of sand or earth containing no rocks or stones; or ii) a conduit suitable for earth burial placed to facilitate cable replacement and to minimize traffic vibration damage; and f) equipped with a metal shield when placed in a common trench involving random
separation with power supply cables or wiring operating at 750.0V or less, in which case the community antenna distribution conductors shall not cross under the supply cables. 24.8.2 Underground Raceway (1) Where community antenna distribution conductors are placed in underground raceway systems:
a) the raceway, including materials, shall be separated from those used for the electric power system by not less than 50.0mm of concrete or 300.0mm of well-tamped earth; b) the raceway shall be located to maintain a minimum depth of 600.0mm in areas subject to vehicular traffic and 450.0mm in all other areas except that, where rock bottom it encountered at shallower depth, the raceway shall be encased in concrete; c) the raceway shall not terminate in the same manhole and the conductors or cable assembly shall not be placed in the same manhole, used for electric po~er system; d) the conductors shall not be placed in the same raceway containing electric lighting, power or Class 1 circuit conductors; and e) the cable sheath shall be suitable for wet locations..
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24.8.3 Underground Block Distribution (1) Where the entire street circuit is run underground and the circuit is placed so.that it is,not liable to be in contact with electric lighting, power, or Class I circuits of more than 380.0V, insulating bushings or raceways shall not be required where the circuit conductors enter a building.
24.9
LIGHTNING ARRESTERS FOR RECEIVING STATIONS
24.9.1 Lightning Arrester (1) A lightning arrester shall:
a) be provided for each lead-in conductor from an outdoor antenna to a receiving station except where such lead-in conductor is protected by a continuous earthed metal shield between the antenna and the point of entrance to the building; b) be located outside the building or inside the building between the point of entrance or the lead-in and the radio set or transformer, and as near as practicable to the entrance to the conductors to the building; and .' c) not be located near combustible material nor in a hazardous location.
24.9.2
Earthing Conductor
24.9.2.1
Material
(1) The earthing conductor shall be of copper, aluminium alloy, copper-clad steel, bronze, or other corrosion-resistant material unless otherwise specified.
24.9.2.2
Insulation
(1) The earthing conductor may be uninsulated,
24.9.2.3
Support
(1) The earthing conductor shall be securely fastened in place and may be directly attached to the supporting surface without the use of insulating supports.
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24.9.2.4
Mechanical protection
(1) The earthing conductor shall be protected where
24.9.2.5
l:XPOSl:U
to mcchunicul injury.
Earthing conductor to be run in a straight line
(1) The earthing conductor shall be run. in as straight a line as is practicable from the lightning arresters of antenna mast, or both, to the earthing electrode.
24.9.3
Earthing Electrode
24.9.3.1
Earthing electrode
(1) The earthing conductor shall be connected to an earthing electrode as specified in Section 7.
24.9.3.2
Earthtng conductors
(1) The earthing conductor may be run either inside or outside the building.
24.9.3.3
Size ofprotective earth
(1) The size of protective earthing conductor for receiving stations providing earth connection for mast and lightning arresters shall be in accordance with the provisions of Section 7.
24.9.3.4
Common earth
(1) A single earthing conductor may be used for both protective and operating purposes; but it must be installed so that disconnection of the operating earth will not be after the protective earth circuit.
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Figure A.5 Through-wired method
442
EBCS-10 1995
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Fig. A.6 Spur-line method
ETHIOPIAN BUILDING CODE STANDARD
SECTION 24: COMMUNITY ANTENNA INSTALLATION
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Figure A.8
Figure A.7 Community aerial system for LF MF, HF and USW reception and three television transmission
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Private wide-band system
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ETHIOPIAN BUILDING CODE STANDARD
EBCS-10 1995
443
ELECTRICAL INSTALLATION OF BUILDINGS
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Figure A.ll Data relevant to the length of, an aerial post
444
EBCS-10 1995
Figure A.12 .Data relevant to the design of an aerial post
ETHIOPIAN BUILDING CODE STANDARD
SECTION 24: COMMUNITY ANTENNA INSTALLATION
Figure A.13 Recommended arrangement of a head station
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