Preliminary Load Calculations

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Section

6 Preliminary Load Calculations

6.1.0 6.1.1 6.1.2 6.1.3 6.1.4 6.1.5 6.1.6 6.1.7 6.1.8 6.1.9 6.1.10 6.1.11 6.1.12 6.1.13 6.1.14 6.1.15 6.1.16

6.1.0

Introduction Prescriptive Unit Lighting Power Allowance (ULPA) (W/ft2), Gross Lighted Area of Total Building Typical Appliance/General-Purpose Receptacle Loads (Excluding Plug-In-Type A/C and Heating Equipment) Typical Apartment Loads Typical Connected Electrical Load for Air Conditioning Only Central Air Conditioning Watts per SF, BTUs per Hour per SF of Floor Area, and SF per Ton of Air Conditioning All-Weather Comfort Standard Recommended Heat-Loss Values Typical Power Requirement (kW) for High-Rise Building Water Pressure–Boosting Systems Typical Power Requirement (kW) for Electric Hot Water–Heating System Typical Power Requirement (kW) for Fire Pumps in Commercial Buildings (Light Hazard) Typical Loads in Commercial Kitchens Comparison of Maximum Demand Connected Load and Maximum Demand by Tenant Classification Factors Used in Sizing Distribution-System Components Factors Used to Establish Major Elements of the Electrical System Serving HVAC Systems Service Entrance Peak Demand (Veterans Administration) Service Entrance Peak Demand (Hospital Corporation of America)

Introduction The following tables are provided to assist the user in estimating preliminary loads for various building types. Considerable judgment should be used in the application of these data. Power densities typically are given in watts per square foot (W/ft2) or volt-amperes per square foot (VA/ft2) and are used interchangeably because unity power factor is assumed for preliminary load calculations. These tables give estimated connected loads. To these the user must apply a demand factor to estimate the actual demand load. Demand factors for buildings typically range between 50 and 80 percent of the connected load. For most building types, the demand factor at the service where the maximum diversity is experienced is usually 60 to 75 percent of the connected load. Specific portions of the system may have much higher demand factors, even approaching 100 percent.

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6.1.1 Prescriptive Unit Lighting Power Allowance (ULPA) (W/ft2), Gross Lighted Area of Total Building TABLE 6.1.1

6.1.2 Typical Appliance/General-Purpose Receptacle Loads (Excluding Plug-In-Type A/C and Heating Equipment) TABLE 6.1.2

(From IEEE Std. 241-1990. Copyright 1990 IEEE. All rights reserved.)

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6.1.3 Typical Apartment Loads TABLE 6.1.3

(From IEEE Std. 241-1990. Copyright 1990 IEEE. All rights reserved.)

6.1.4 Typical Connected Electrical Load for Air Conditioning Only TABLE 6.1.4

(From IEEE Std. 241-1990. Copyright 1990 IEEE. All rights reserved.)

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6.1.5 Central Air Conditioning Watts per SF, BTUs per Hour per SF of Floor Area, and SF per Ton of Air Conditioning TABLE 6.1.5

6.1.6 All-Weather Comfort Standard Recommended Heat-Loss Values TABLE 6.1.6

(From IEEE Std. 241-1990. Copyright 1990 IEEE. All rights reserved.)

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6.1.7 Typical Power Requirement (kW) for HighRise Building Water Pressure–Boosting Systems TABLE 6.1.7

(From IEEE Std. 241-1990. Copyright 1990 IEEE. All rights reserved.)

6.1.8 Typical Power Requirement (kW) for Electric Hot Water–Heating System TABLE 6.1.8

(From IEEE Std. 241-1990. Copyright 1990 IEEE. All rights reserved.)

6.1.9 Typical Power Requirement (kW) for Fire Pumps in Commercial Buildings (Light Hazard) TABLE 6.1.9

(From IEEE Std. 241-1990. Copyright 1990 IEEE. All rights reserved.)

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6.1.10 Typical Loads in Commercial Kitchens TABLE 6.1.10

(From IEEE Std. 241-1990. Copyright 1990 IEEE. All rights reserved.)

As an alternative to the preceding table, you may use 25 W/ft2 for commercial kitchens using natural gas for cooking or 125 W/ft2 for electric cooking. The applicable square footage in calculating kitchen floor area should include cooking and preparation, dishwashing, storage, walk-in refrigerators and freezers, food serving lines, tray assembly, and offices. Note:

6.1.11 Comparison of Maximum Demand TABLE 6.1.11

(From IEEE Std. 241-1990. Copyright 1990 IEEE. All rights reserved.)

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6.1.12 Connected Load and Maximum Demand by Tenant Classification TABLE 6.1.12

(From IEEE Std. 241-1990. Copyright 1990 IEEE. All rights reserved.)

6.1.13 Factors Used in Sizing Distribution-System Components TABLE 6.1.13

(From IEEE Std. 602-1996. Copyright 1996 IEEE. All rights reserved.)

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6.1.14 Factors Used to Establish Major Elements of the Electrical System Serving HVAC Systems TABLE 6.1.14

For a primary cooling system comprised of electrical centrifugal chillers, chilled water pumps, condenser water pumps, and cooling tower fans, a factor of 1.7 kVA/ton provides a good estimate.

Note:

(From IEEE Std. 602-1996. Copyright 1996 IEEE. All rights reserved.)

6.1.15 Service Entrance Peak Demand (Veterans Administration) TABLE 6.1.15

(From IEEE Std. 602-1996. Copyright 1996 IEEE. All rights reserved.)

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6.1.16 Service Entrance Peak Demand (Hospital Corporation of America) TABLE 6.1.16

(From IEEE Std. 602-1996. Copyright 1996 IEEE. All rights reserved.)

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