Minimum branch circuit size for Level II EVSE with 32-ampere rating?

Minimum branch circuit size for Level II EVSE with 32-ampere rating?

• A. 32 A
• B. 35 A
• C. 40 A
• D. 55 A

Answer: (C)

Sizing the branch circuit for Level II charging uses a 125% rule because the charger can run for long periods during a session. The device is rated to draw up to 32 A, and as a continuous load it must be sized at 1.25 times that current. 32 A × 1.25 equals 40 A, so the smallest safe branch-circuit size is 40 A. In practice this means a 40-A, two-pole breaker with conductors suitable for that rating (typically 8 AWG copper or 6 AWG aluminum). A 32 A circuit would be undersized for continuous operation; 35 A isn’t a standard rating and still wouldn’t meet the 125% requirement; 55 A would exceed what the calculation calls for.

Sizing the branch circuit for Level II charging uses a 125% rule because the charger can run for long periods during a session. The device is rated to draw up to 32 A, and as a continuous load it must be sized at 1.25 times that current. 32 A × 1.25 equals 40 A, so the smallest safe branch-circuit size is 40 A. In practice this means a 40-A, two-pole breaker with conductors suitable for that rating (typically 8 AWG copper or 6 AWG aluminum). A 32 A circuit would be undersized for continuous operation; 35 A isn’t a standard rating and still wouldn’t meet the 125% requirement; 55 A would exceed what the calculation calls for.