Master Electrician Exam (NEC)Load CalculationsEasy
A master electrician is performing a service load calculation for a single-family dwelling. The dwelling has a 240V, 50A electric vehicle supply equipment (EVSE) installed. What is the demand load for this EVSE to be included in the service calculation, according to NEC 220.57?
- A12,000 VA
- B6,000 VA
- C9,600 VA
- D4,800 VA
Show answer & explanationAnswer & explanation
Correct answer: A. 12,000 VA
According to NEC 220.57, the demand load for electric vehicle supply equipment is the total nameplate rating of the EVSE. For a 240V, 50A EVSE, the nameplate rating is 240V * 50A = 12,000 VA. No demand factor is applied to EVSE loads unless specific conditions outlined in 220.57(B) are met, which are not mentioned in this scenario.
Why the other options are wrong
- B. This value is incorrect and does not represent the full nameplate rating.
- C. This would be applying a 80% demand factor (12,000 VA * 0.8), which is not the general rule for EVSE under 220.57.
- D. This value is incorrect and does not represent the full nameplate rating or any standard demand factor.
EVSE Demand Load (NEC 220.57)
The demand load for electric vehicle supply equipment (EVSE) is generally considered to be its total nameplate rating, unless specific conditions for demand factor application are met as outlined in NEC 220.57(B).
- NEC 220.57 covers EVSE load calculations.
- Typically, the full nameplate rating is used for demand.
- Demand factors are only applied under specific conditions not usually present for single dwelling units.
Memory trick: EV charging, full power. No discounts unless it's complex.