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NOTE: This is an unformatted excerpt from our online fire protection training library.

Load Calculations

Demand Factors

Motors

There are some special rules for motors, but the demand factors for motors are based on Article 430 and require special permission from the authority having jurisdiction.

There are other specific requirements for demand factors for other types of loads in other sections:

220.51 for fixed electric space heating in any occupancy and for dwelling units 220.53 for multiple appliances 220.54 for electric clothes dryers 220.55 for electric ranges 220.56 for commercial kitchen equipment 220.60 for permission to exclude the smaller of two noncoincident loads

Demand factors are applied differently in different situations. In most single-family dwellings, for example, there would be only one electric clothes dryer and there would be no demand factor. In a multifamily dwelling, where there are multiple dryers in the same service or feeder, the requirements recognize that it would be unlikely for all of them to be operating precisely at the same time, so demand factors can be used.


For appliances fastened in place (other than ranges, clothes dryers, and space-heating and air-conditioning equipment), feeder capacity must be provided for the sum of these loads; for a total load of four or more such appliances, a demand factor of 75 percent is permitted by Section 220.53.

NOTE: This is an unformatted excerpt from our online fire protection training library.

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