What Size Wire for a 32 Amp EV Charger?

A 32A EV charger needs #8 copper or #8 aluminum conductors on a 40A breaker. EV charging is a continuous load, so the circuit is sized at 125% of the charger's output (32 × 1.25 = 40A, rounded up to a 40A standard breaker per NEC 625.41 and 210.20(A)). The wire is sized at the 75°C column of NEC Table 310.16, which applies because EV chargers and breakers are 75°C-rated equipment. The equipment grounding conductor is #10 copper per NEC Table 250.122. If the run uses NM-B cable (Romex), the 60°C column applies (NEC 110.14(C)(1)(a), 334.80), so use #8 copper instead.

A 40A double-pole breaker. Because EVSE is a continuous load, NEC 625.41 requires the overcurrent device to be rated at least 125% of the charger's output: 32 × 1.25 = 40A, and the next standard breaker size is 40A.

Yes. A 32A Level 2 charger, whether hardwired or plug-in, must be on its own dedicated branch circuit that serves no other load (NEC 625.40). A plug-in unit on a NEMA receptacle also needs GFCI protection at the breaker (NEC 625.54); most hardwired units have built-in CCID/GFCI and do not.

#8 copper carries a 40A circuit at ampacity, but on long runs voltage drop, not ampacity, sets the limit. Past roughly 100 feet you may need to upsize one gauge to stay within the 3% drop recommendation. Enter your exact distance in the calculator below to check.