17th Edition Exam Questions

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PAPER 11

17th Edition 100 Questions 1.

Basic Protection and Fault Protection can be provided by a SELV supply. One suitable safety source of supply would be a A. B. C. D.

2.

Where a circuit forms part of a TN system, the maximum permissible earth fault loop impedance (Z,) for a 13 A socket outlet circuit used for portable equipment and protected by a 30amp 1361 fuse is A B C D

3.

0.4 s 0.2 s 1.0 s 5.0 s.

The result of the earth fault loop impedance (Zs) being higher then the maximum tabulated values allowed in BS7671 is that the; A B C D

5.

2.64 Ω 1.84 Ω 1.5 Ω 2.0 Ω

In the event of an earth fault on a TT supply, the Fault Protection requirements of the final circuit supplying the 230 V stationary equipment are satisfied when disconnection occurs with in A B C D

4.

50V Storage battery 230V diesel generator 230/110V single-phase generator 230 /50V auto-transformer.

short circuit current will not operate the protective device current rating of the protective device must be increased current rating of the protective device must be reduced cable will be damaged before the protective device will operate under earth fault conditions.

Which one of the following is a non-statutory document? A B C D

HSE GS38 Electricity at work regulation 1989 Electricity Safety Quality and Continuity Regulations BS7671 (2008)

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PAPER 11

Type B MCB’s manufactured to BSEN60898 have an instantaneous trip current of between _____________their rated design current (In) A B C D

7.

The nominal rating of an overcurrent protective device should be A B C D

8.

0.46 ohms Ω 0.80 ohms Ω 0.90 ohms Ω 0.75 ohms Ω

Suitable precaution shall be taken where either a reduction in voltage or a loss and subsequent restoration of voltage A B C D

11.

double-pole switch fuse Fireman’s switch semi-conductor device a remotely switched contactor

The end to end resistance of the line and neutral conductors on a 2.5mm/1.5mm PVC/PVC twin and CPC cable, is measured as 0.45 Ω and 0.46 Ω, respectively. What would the expected end to end resistance of the CPC be A B C D

10.

not less than the design current greater than the current carrying capacity of the conductors 1.45 times the load current equal to the prospective short circuit current.

As means of isolation in a circuit it is NOT permissible to use a A B C D

9.

2.7 to 4 times 3 to 5 times 4 to 7 times 7 to 10 times

in a routine event could cause danger occurs infrequently will not cause danger.

With in a paper mill having a conduit wiring system, insulation fault protection must be provided using an RCD having a residual operating current not exceeding A B C D

30 mA 300 mA 500 mA 750 mA

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PAPER 11

Which one of the following is NOT a classification of external influence? A B C D

13

A Functional switching device shall be provided for A B C D

14.

not expected to be continually fully loaded designed to carry its maximum load continually supplying thermostatically controlled water heaters supplying thermal storage heater

Where an installation incorporates an r.c.d. the label at the origin of the installation must indicate the maximum period between tests on the circuit r.c.d. is A B C D

17.

are recorded as a departure from the regulations are recorded as an installed drawing use maintenance free terminals are used on lighting circuits only

Diversity factors may be applied to a circuit which is A B C D

16.

Emergency Isolation each part of a circuit that may need to be controlled independently every socket outlet Shop front lighting exceeding low voltage

Junction boxes must be accessible for inspection and maintenance. BS7671 allows for an exception provided that they A B C D

15.

Current rating Environmental conditions Construction of building Utilisation

quarterly monthly annually weekly

All fuses and circuits breakers shall have an indication of the A B C D

name of the manufacture intended application model or BS number intended nominal current

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PAPER 11

Where a TT system is in use, the preferred protective device is a A B C D

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Which one of the following is excluded as a protective earth electrode? A B C D

20

3 x I∆n 5 x I∆n 1 x I∆n 1.5 x I∆n

All circuits supplying sockets outlets up to a rating of 32 A, located within an unsupervised environment must incorporate a ____________ to reduce the risk of fault contact A B C D

23.

4.0 mm2 16 mm2 25 mm2 50 mm2

When testing a 100mA RCD the maximum test current applied via the test instrument will be (I∆n) A B C D

22.

Underground structural metal work embedded in foundation Welded metal reinforcement of concrete embedded in the earth Earth plates Metalwork of public water services

A steel earth conductor mechanically protected, but not protected against corrosion is buried in soil. The minimum size of the earthing conductor is A B C D

21

Moulded Case Circuit Breaker Time delayed residual current device + suitable fuse BS 1361 Type 1 cartridge fuse link BS 88 HRC Fuse

fuse having a suitable time/current characteristic Type B circuit breaker to BS EN 60898 30mA residual current device switch-disconnector to BS EN 60947-3

The means of connection to a caravan pitch socket outlet, shall be a plug confirming to A B C D

BS EN 60309-2 BS EN 60309-1 BS 1363-1 BS 5733

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PAPER 11

In order to reduce the effects of eddy currents when conductors enter a ferrous enclosure, they should be so arranged that A B C D

25

In agricultural and Horticultural premises all electrical wiring accessories shall have a minimum rating of A B C D

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IPX3 IPX4 IPX5 IPX6

The recommended mounting height for electric hookups on a tidal estuary is A B C D

29

in plastic enclosure only at the origin of the supply so that its operation will not be impaired by magnetic fields caused by other equipment at a height of at least 450mm from the floor level

Electrical equipment installed in Zones 1 and 2 of communal baths or communal showers, where water jets are likely to be used for cleaning purposes, shall have a minimum degree of protection against external influences of A B C D

28

IPXXB IP44 IPX6 IPX7

An RCD’s should be located only A B C D

27

each conductor of an individual circuit takes approximately the same value of the current they are not individual surrounded by the ferrous material they are terminated in the correct phase sequence they are physically separated from the conductor of the other circuits within the enclosure

450mm above the high tide line 600mm above the high tide line 1000mm above the high tide line 1250mm above the high tide line

Where can the electrical connection (eg flex outlet plate) be sited for a sauna heater? A B C D

Either Zones 1,2 or 3 Zones 1 and 2 Zones 1 Zones 2

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PAPER 11

What does the symbol represent?

A B C D 31

In an area where there is no vehicle movement on a caravan park, the minimum height for overload cables is A B C D

32

Either Permanent connection or BSEN 60309-2 plug and socket BSEN 60309-2 plug and socket only Permanent connection only 4mm cable or flex

When carrying out an inspection in accordance with BS 7671, which one of the following MUST be inspected A B C D

35

Placing out of reach Automatic Disconnection of Supply Double Insulation Insulation of Live parts

Equipment having a protective conductor exceeding 10mA shall be connected to the supply by A B C D

34

3.5 m 6.0 m 7.5 m 8.0 m

Basic & fault protection can be provided by A B C D

33

Suitable for use with Fluoresecent lamps Faulty equipment Suitable for mounting of flammable surfaces Fairground Supply

The presence of fire barriers The prospective short circuit current The maximum permissible voltage drop Site applied insulation

A legible diagram, chart or table relating to an insulation must be provided to indicate the A B C D

route followed be each circuit earth fault loop impedance of the supply capacity of each distribution board type and composition of each circuit

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PAPER 11

An r.c.d. protected socket outlet circuit is connected to a TT earthing system. Operating the r.c.d.’s integral test button will verify A B C D

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Where a given test result fails to comply with BS 7671 part 6, the procedure to adopt after the fault has been rectified is that A B C D

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electricity supplier has been informed local authority has been informed existing equipment is adequate for any additional load existing equipment meets BS and BS EN standards

On completion of a new industrial installation, an electrical installation Certificate should be signed by A B C D

41

2 MΩ 1Ω 0.5 Ω 1 MΩ

No alteration, temporary or permanent shall be made to an existing installation unless the A B C D

40

the test and those that follow should be repeated the whole sequence of tests should be repeated only the test that indicated the fault should be repeated the test that indicated the fault and those tests which may have been influenced by the fault that preceded it should be repeated

When testing a circuit of a 230v, the minimum value of insulation resistance to earth with all fuses in place and all the line and neutral conductors connected together is A B C D

39

the continuity of the main earthing conductor the effectiveness of the earth electrode the continuity of the final circuit protective conductors that the internal mechanism of the devise operates

the owner or manager of the factory a competent person or persons the legal department representing the owner of the premises the main building contractor

The frequency of the periodic inspection and testing for an installation shall be determined by the Supply company recommendations B installation’s maximum demand C nature of the supply D type of installation

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PAPER 11

When carrying a fault current of 205 A, a 60 A protective device to BS 3036 should operate in A B C D

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The external influence having a classification of AD7 indicates A B C D

44

the socket outlet is specifically labelled for use with a particular appliance supplementary bonding is installed the socket outlet and cable supplying are surface mounted the circuit is of a 16 amp radial type

Which one of the following is not a benefit of dividing the installation up into a number of final circuits is to A B C D

47

when an additional circuit is connected to an existing installation for new installations connected to a single phase supplies of 100 A or less for alterations or additions that do not extend to the provision of a new circuit for new installations limited to domestic applications only

An exception to Additional Protection as required by regulation 411..3.3 is when A B C D

46

humidity immersion in water dust in the atmosphere high levels of vibration

A Minor Works Certificate should be issued A B C D

45

0.1s 0.4s 5.0s 500s

mitigate the effect of electromagnetic interference prevent the indirect energising of a circuit intended to be isolated avoid hazards and minimise the inconvenience in the event of a fault make testing easier

Uo is correctly defined as the A B C D

The output voltage of the supplying distribution transformer The nominal a.c. rms Line voltage to Earth The declared voltage in the UK and Ireland Single phase supply voltage

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PAPER 11

A Line conductor is typical defined as A B C D

49

The measured voltage at the farthest point of utilisation on alighting circuit in a commercial premise, fed from the public distribution network, is found to be 218. The overall voltage drop in % terms is and is ______________? A B C D

50

Special Locations Inspection and Testing Protection against over-current Earthing

TT systems have a stated disconnection time of 0.2s, BS&^&! States that this may be increased to 0.4s where A B C D

53

16mm conductor from CCU to MET 10mm conductor to incoming water pipe 16mm conductor between hot and cold water pipes 16mm conductors from the MET to and earth electrode

Part 6 of BS7671 2008 deals with A B C D

52

3% acceptable 3% not acceptable 5% not acceptable 5% acceptable

Which of the following best describes a Protective Bonding Conductor? A B C D

51

A conductor in an a.c. system other than a neutral or cpc A conductor in an a.c. system including the neutral but excluding the cpc one phase of a three phase system A conductor in an a.c. system other than neutral or cpc or equivalent in a d.c. system, unless otherwise defined

a 30mA RCD is used in addition to overcurrent protection Protective Equipotential Bonding is in place and disconnection time will be met by the overcurrent device only Supplementary Bonding is installed in addition to Protective Equipotential Bonding an earth rod and 100mA Time Delayed RCD is fitted

Alight fitting suitable for use in Zone 1 of a bathroom must be A B C D

SELV a Class II fitting IPX4 or above RCD protected

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PAPER 11

To comply with BS7671 2008, cables concealed inside a partition wall at a depth of less tha 500mm, must be A B C D

55

The IP rating code for barriers covering exposed live parts inside a distribution board is A B C D

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TNS TT TNCS PME

The Scope of BS7671 2008 excludes which type of installation? A B C D

59

Earth Steel conduit Earthed metal trunking Earth metal channelling Outer armours of SWA cable

The perfect type of supply for a caravan parks is A B C D

58

IP2X IP4X IPXXB IP55

Which of the following is not considered to be suitable metallic screening for cables installed below plaster depth in a domestic installation A B C D

57

Adequately Earthed provided with Additional Protection Mechanically Protected installed in Safe Zones only

Oil rigs Circuses Marines Exhibition Stands

Why may 13 amp BS1363 socket outlets used in a controlled laboratory environment, not require RCD Proctection? A B C D

There may be a possibility of nuisance tripping There may be electromagnetic interference from other equipment The workplace is controlled and is supervised by skilled persons IT equipment may have high protective conductor current

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PAPER 11

Basic protection can be achieved by A B C D

61

The supply circuit of insulation monitoring devices must be installed A B C D

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Surge protection Nothing because it cant be sorted Increase the size of the neutral Install a RCD

Which of the following is a method of fault protection? A B C D

65

0.3m 0.5m 0.8m 1.1m

In a TP & N installation servicing an office with IT equipment and a high harmonic disturbance. How would the harmonic influence be combated? A B C D

64

at the furthest point of the installation as close as practical to the origin of the installation in series with the load to provide protection against shock

Except A B C D

63

Limiting the current which can pass through the body Ensuring all extraneous parts are at equal potential Automatic disconnection of the supply during earth fault conditions Separation of the supply and load by means of an isolating transformer

Placing out of reach Insulation of live parts Obstacles Reinforced insulation

The Max Zs for a TT system with a 300mA RCD A B C D

1667 ohms 500 ohms 167 ohms 100 ohms

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PAPER 11

Regulation 314.1 states that every installation shall be divided into circuits as necessary to A B C D

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An RCD installed for the protection against fire must have a rating of A B C D

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RCD have to be tested regularly table 53.2 does not permit RCD’s to be used as an isolator They maybe at risk from being overloaded danger could arise from the failure of just a single circuit

External influence classification AA4 relates to A B C D

72

The installation is under the control of a supervised person Refrigeration equipment containing valuable frozen goods Where no over-current protection is fitted Quarterly manual RCD testing would be impracticable

An installation should not be protected by one RCD mainswitch controlling all overcurrent devices because A B C D

71

50 oC 60 oC 70 oC 80 oC

A Residual Current Monitor (RCM) may be used in preference to an RCD where A B C D

70

30 mA 100mA 300mA 500mA

Ceiling heating systems should be limited to a maximum temperature of? A B C D

69

Prevent danger to persons and live stock Comply with Electricity at Work Regulations Avoid hazards and minimise inconvenience in the event of a fault Comply with building regulations

Presence of Flora Atmospheric Humidity Ambient Temperature Light Dust

An active RCD to BS7671 will perform which functions in the event of a supply failure A B C D

Lock Automatically trip to disconnect the supply Remain in the on position but stay silent Remain in the on position but alarm

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PAPER 11

A 32amp BSEN60898 MCB has a max Zs of 1.44 ohms. Assuming that the MCB will operate instantaneously if 5 times its rated current flows, what is the level of fault current at this impedance at 230V A B C D

74

Standard Volt Drop calculations do not apply to which wiring method A B C D

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50v 110v 25v 230v

Electrical installations for trade shows and exhibitions are subject to number of risks. Part 6 of BS7671 recommends that such installations be tested A B C D

78

0,1 & 2 1, 2 & 3 A, B & C A1, B2 & C3

The maximum touch voltage in a RLV supply is A B C D

77

Where site applied insulation is used Busbar Trucking Systems Cables supported by catenery wires Mineral insulated cables

The three Zones for swimming pool installations are A B C D

76

32 amps 160 amps 67 amps 331 amps

at period specified by the designer every three months every six months after each erection/ assembly on site

The maximum length of run for a 10mm protective bonding conductor before it can exceeds 0.05Ω is A B C D

26m 24m 27m 25m

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PAPER 11

For the purpose of earthing a TT or IT systems the main earthing terminal shall not be connected via an earthing conductor to A B C D

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BS 1363-4 relates to which type of accessory? A B C D

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non-conducting location ADS earth-free equipment bonding electrical separation

The recognised harmonised colour for Line conductors is A B C D

84

AG1 AG2 AG3 AG4

To reduce the risk of shock from the metalwork of Class I street located equipment, protection should be by A B C D

83

Fused connection units 13amps socket outlets Unswitched socket outlets Fuses

For cables crossing public areas and roadways at fairgrounds, the cable should be designed to withstand external influence to at least A B C D

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A solid metal earth plate A metallic pipe belonging to another utility service Structural steel Earth rods

Blue Grey Brown Black

A phase 4 wire system is also known as A B C D

TP & N TNS TNCS TN

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PAPER 11

The maximum current carrying capacity for 1.0mm twin and earth, installed to reference method C A B C D

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1.5mm SWA 70 oC thermoplastic insulated cable, has a rated volt drop of A B C D

87

0.5 Ω 2 MΩ 0.5 MΩ 1 MΩ

The maximum rating for an RCD at the origin of the supply mobile circus tent is A B C D

90

Protective Equipotential Bonding conductors Site applied insulation Double insulated meter tails SELV conductors

When carrying out a PIR on a 230v installation, the minimum value of insulation resistance to earth with all MCBs in place and the Line and Neutral conductors connected together is A B C D

89

25 mV/A/m 26 mV/A/m 21 mV/A/m 27 mV/A/m

Non sheathed cables shall be enclosed in conduit or trunking, but this requirement does not apply to A B C D

88

11.5 amps 16 amps 13 amps 10.5 amps

30mA 100mA 300mA 500mA

On completion of a new industrial installation, an Electrical Installation Certificate should be signed by A B C D

the owner or manager of the factory a competent person or persons the legal department representing the owner of the premises the main building contractor

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PAPER 11

The frequency of periodic inspection and testing for an installation shall be determined by the A B C D

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When carrying a fault current of 205 A, a 60 A protective device to BS 3036 should operate in A B C D

93

when an additional circuit is connected to an existing installation For new installations connected to single phase supplies or 100A or less for alteration or additions that do not extend to the provision of a new circuit for new installations limited to domestic applications only

In order to avoid damage from vehicles and other users, cables supplying mooring hookup cabinets, shall be laid at recommended depth of A B C D

96

humidity immersion in water dust in the atmosphere high level of vibration

A Minor Works Certificate should be issued A B C D

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0.1s 0.4s 5.0s 500s

The external influence having a classification of AD7 indicates A B C D

94

supply company recommendations installation’s maximum demand nature of the supply type of installation

450mm 500mm 600mm 1000mm

The maximum operating temperature for thermoplastic insulated cables is A B C D

105 oC at the sheath 70 oC at the sheath 90 oC at the conductor 70 oC at the conductor

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PAPER 11

Multicore cables installed in cable trunking that is flush with the floor are classed as which reference method A B C D

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Zone 2 in a domestic bathroom extends to A B C D

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2.25m vertically from the top surface and horizontally 1.2m from the bath 2.25m vertically from the top surface and horizontally 0.6m from the bath 2.5m above floor level and horizontally 0.6m from the bath 2.25m above floor level and horizontally 0.6 from the bath

External influence classification AD relates to Presence of A B C D

100

D C B A

Moisture Water Steam Solid foreign bodies

Which of the following best describes a PEB – Protective Equipotential Bond A B C D

16mm conductor from CCU to MET 10mm conductor to incoming water pipe 6mm conductor between hot and cold water pipes 16mm conductor from the MET to an earth electrode

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PAPER 11

Answers 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

A B B D D B A C D B B A B C A A D B D D C C A B B C D C C C A C A A D D A D C B D C B C A D B D C B

51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100

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B B C B C C A A C A B ? A D C C C D B D C B B B A C D D B A B B D A B A A B C B D C B C B D C D B B