Master Electrician Exam (NEC)Load CalculationsMedium
A master electrician is calculating the service load for a large commercial office building. The building has 15 kW of fixed electric space heating and 12 kW of air-conditioning load. What is the demand load for these loads to be included in the service calculation, according to NEC 220.60?
- A8 kW
- B27 kW
- C12 kW
- D15 kW
Show answer & explanationAnswer & explanation
Correct answer: D. 15 kW
According to NEC 220.60, when calculating the feeder or service load for fixed electric space heating and air-conditioning, only the larger of the two connected loads is required to be used. In this case, the fixed electric space heating is 15 kW, and the air-conditioning load is 12 kW. The larger of these two is 15 kW.
Why the other options are wrong
- A. This value is incorrect and does not represent either the heating or AC load.
- B. This would be the sum of both loads, which is incorrect according to NEC 220.60.
- C. This is the smaller of the two loads, which is incorrect according to NEC 220.60.
Heating & A/C Demand (NEC 220.60)
The demand load for fixed electric space heating and air-conditioning systems, where only the larger of the two connected loads is required to be included in the service or feeder calculation.
- NEC 220.60 governs these calculations.
- Only the larger of the heating or A/C load is counted.
- This accounts for the fact that both systems are not typically used simultaneously at their maximum capacity.
Memory trick: Heating OR Cooling, never both full blast.