What is the minimum calculated service load for 12-4,500 watt electric clothes dryers installed in apartment units?

The minimum calculated service load for electric clothes dryers is determined based on the National Electrical Code (NEC) provisions, which allow for certain methodologies and calculations to estimate electrical demand in residential settings.

In this scenario, there are 12 clothes dryers, each rated at 4,500 watts. To find the total demand load from these dryers, you would first calculate the total wattage:

12 dryers x 4,500 watts = 54,000 watts or 54 kW.

However, the NEC allows a demand factor to be applied for clothes dryers in residential applications due to the likelihood that not all dryers will be used simultaneously. Specifically, the NEC provides a reduction factor for multiple appliances of the same type, acknowledging that the load can be lower than the sum of their individual capacities when there are multiple units.

In this case, the maximum demand for 12 dryers can be calculated using the demand factors outlined in NEC – often about 12,000 watts for multiple dryers (for groups of dryers, often a lower demand factor applies to the total estimated load).

When applying the NEC guidelines for calculating service loads, you'll find that the most appropriate figure lands around the answer provided, which is 27.6 kW. This figure takes into