Master Electrician Exam (NEC)Special Occupancies, Equipment, and ConditionsMedium
A master electrician is installing an electric vehicle (EV) charging station at a multi-family dwelling. The EV charging equipment has a continuous rating of 40 amperes. What is the minimum continuous current rating required for the overcurrent protective device (OCPD) supplying this EV charging equipment?
- A80 amperes
- B50 amperes
- C40 amperes
- D60 amperes
Show answer & explanationAnswer & explanation
Correct answer: B. 50 amperes
According to NEC 625.41, EV charging equipment is considered a continuous load. For continuous loads, the branch-circuit OCPD must have a rating not less than 125% of the equipment's continuous current rating. Therefore, 40 A * 1.25 = 50 A.
Why the other options are wrong
- A. This rating is significantly higher than the minimum required.
- C. This rating is too low; continuous loads require a 125% factor.
- D. This rating is higher than the minimum required, but 50A is the minimum.
EV Charger OCPD Sizing (Continuous)
Sizing the overcurrent protective device for electric vehicle charging equipment, which is considered a continuous load.
- EV charging is a continuous load.
- OCPD must be rated at 125% of the load.
- NEC 625.41 governs this.
Memory trick: Charging an EV is like running a marathon, it needs 25% extra endurance.