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Level 2 Charger Breaker Size Calculator

Size the breaker and wire for a Level 2 EV charger using the NEC 125% continuous-load rule. Enter your charger's output current to get the required breaker size, minimum copper wire gauge, and charging power.

The charger's max output, not the breaker. Common: 32 A, 40 A, 48 A.

Circuit voltage

Required breaker

50 A

Min. copper wire (75°C)
8 AWG
Continuous load (125%)
50 A
Charging power
9.6 kW

NEC sizes the breaker at 125% of a continuous load (625.41, 240.6) and the wire is the minimum 75°C copper (Table 310.16).

This assumes the breaker and charger terminals are rated 75°C (NEC 110.14(C)); 60°C-rated terminations, long runs (voltage drop), aluminum, or high heat may require a larger gauge.

A real install also needs GFCI protection (NEC 210.8 / 625.54), a permit, and inspection. Your local Authority Having Jurisdiction (AHJ) may amend the NEC. Always confirm with a licensed electrician and local code.

Charger and receptacle for this circuit

The wall unit runs 48 A hardwired on a 60 A breaker, or 40 A plugged into a 14-50 on a 50 A breaker. For the plug-in route, use a heavy-duty 14-50 receptacle built for hours of continuous load, not a residential-grade range outlet. Both picks take copper conductors only. The install is a permitted job for a licensed electrician.

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All Level 2 charger picks

Frequently asked questions

EV charging is a continuous load, so the NEC requires the breaker to be rated for 125% of the charger's current. A 40A charger needs a 50A breaker (40 × 1.25 = 50); a 48A charger needs a 60A breaker. Always round up to a standard breaker size.

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Sources & standards

This tool's methodology and data follow US standards and authoritative public datasets: