What breaker and wire does an EV charger need?
Enter the charger, get the breaker, the wire and the charging power instantly.
What size breaker does an EV charger need?
NEC 625.41 says the overcurrent protection for an EV charger (EVSE) must be at least 125% of its maximum current, and EV charging counts as a continuous load (625.42). Multiply the charger's amps by 1.25 and go up to the next standard size: a 32 A charger needs a 40 A breaker, a 40 A charger 50 A, a 48 A charger 60 A and an 80 A charger 100 A. The EPA gives the same example: a 40-amp Level 2 charger needs a dedicated 50-amp circuit.
What wire size do I need for an EV charger?
The branch-circuit conductors need the same 125% (NEC 210.19(A)), and this calculator sizes them to carry the breaker. For a 50 A breaker that means 8 AWG copper in the 75°C column of NEC Table 310.16 (50 A), or 6 AWG copper NM cable in the 60°C column (55 A). Aluminum needs a size larger. For a long run, enter its length: in the 75°C column a 40 A charger 100 ft from the panel drops 2.6% on 8 AWG copper, but at 150 ft the drop would be 3.9%, so the calculator moves up to 6 AWG to stay within 3%.
Why 125%, and how much can the charger draw?
A continuous load runs at full current for three hours or more, and breakers and wire are only loaded to 80% of their rating for that. So a circuit supports a charger rated at 80% of the breaker: 40 A on a 50 A breaker, which at 240 V is 9.6 kW. Switch the calculator to Existing breaker to see what your breaker can feed. Charging power is volts times amps: a 32 A charger at 240 V is 7.68 kW.
Plug-in or hardwired?
A plug-in charger connects through a matching nonlocking receptacle, such as a 250 V, 30 or 50 A outlet, and NEC 625.54 requires GFCI protection for receptacles used for EV charging. Chargers that do not use a receptacle have to be permanently wired (625.44). Either way, a charger rated over 16 A or 120 V needs its own branch circuit (625.40), and one rated over 60 A needs a readily accessible disconnect (625.43).
How fast will it charge the car?
The EPA says Level 2 chargers typically range from 16 to 80 amps, with 30 to 40 amps more common, and add around 25 to 40 miles of range per hour. How many miles per kWh depends on the car, so this calculator stops at the power; put the kW into the EV charging calculator for charging time and cost.
Sources: NFPA 70 (National Electrical Code), 2023 edition, Article 625 — sections 625.40 to 625.44, 625.54 — and sections 240.4(D), 240.6(A) and Table 310.16, read in NFPA's published code-development documents; the 2026 edition has since been published, and adoption varies by jurisdiction. U.S. EPA, “Getting Started with Home EV Charging”. Charging time and cost: EV charging calculator. Other loads: breaker size, wire size and voltage drop calculators. How we check our calculators.