Master Electrician Exam (NEC)Load CalculationsMedium
A single-family dwelling unit has a 240V, 40A electric vehicle supply equipment (EVSE) installed. According to NEC 220.57, what is the minimum demand load that must be included for this EVSE in the service calculation?
- A9.6 kW
- B8 kW
- C12 kW
- D19.2 kW
Show answer & explanationAnswer & explanation
Correct answer: A. 9.6 kW
According to NEC 220.57, the demand load for electric vehicle supply equipment (EVSE) shall be calculated at 100% of the nameplate rating of the EVSE. The nameplate rating is derived from the voltage and current: 240V * 40A = 9600 VA or 9.6 kW.
Why the other options are wrong
- B. This option might misinterpret the voltage or current rating, or apply an incorrect demand factor.
- C. This option might be a common incorrect demand factor or a miscalculation.
- D. This option likely doubles the load, which is incorrect for EVSE calculations.
EVSE Demand Load (NEC 220.57)
Electric Vehicle Supply Equipment (EVSE) loads are always calculated at 100% of their nameplate rating for feeder and service calculations.
- Applies to all EVSE installations.
- No demand factors are permitted for EVSE loads.
- Calculated at 100% of the equipment's rated current or power.
Memory trick: EVSE: Electric Vehicle, Straight-up Exact.