EV charging · 8 min

EV charger circuit sizing for a Level 2 charger

A Level 2 charger is the biggest continuous load most houses will ever add. It runs for hours at full current, which is exactly why the NEC sizes its circuit with a margin — and why it deserves a place on the electrical plan before the garage wall is finished.

Updated: October 2026

An individual 240 V circuit

Article 625 treats EV charging as a continuous load. The charger needs an individual branch circuit with no other outlets on it (625.40). Most home chargers run on 240 V, between the two legs of the split-phase service.

The 125 % rule

The overcurrent protection must be at least 125 % of the charger’s maximum current (625.41). Start from the power: a 7.4 kW charger draws about 31 A at 240 V; 125 % gives 38.5 A, so the next standard breaker is 40 A. A 48 A charger needs a 60 A breaker.

  • 3.7 kW (about 16 A): 20 A breaker, 12 AWG copper.
  • 7.4 kW (about 31 A): 40 A breaker, 8 AWG copper.
  • 9.6 kW (40 A): 50 A breaker, 6 AWG copper.
  • 11.5 kW (48 A): 60 A breaker, 4 AWG copper.
  • 19.2 kW (80 A): 100 A breaker, 1 AWG copper — check that the service can carry it.

Plug-in or hardwired?

A plug-in charger on a NEMA 14-50 or 6-50 receptacle is convenient, but the receptacle needs GFCI protection (625.54), and a receptacle is not designed for hours of full load every night. A hardwired charger is often the better choice above 32 A.

In a garage or outdoors, 210.8(F) also asks for GFCI protection on hard-wired outlets up to 50 A. Some jurisdictions accept the charger’s built-in protection instead: ask your inspector.

Can the service handle it?

Adding 40 A of continuous load to a 100 A service with an electric range, dryer and water heater can exceed its capacity. An Article 220 load calculation answers the question; load management systems that throttle the charger when the house is busy are an alternative to a service upgrade.

Planning the charger in Planelico

Place the wallbox in the garage or outdoors and choose its power: 7.2, 9.6, 11.5 or 19.2 kW. Planelico creates the individual circuit, sizes the breaker at 125 % with the next standard rating, picks the wire size in AWG, and adds a point to check reminding the installer of the Article 625 requirements. Wire size must still be confirmed for the actual run length and voltage drop.

Quick method with Planelico

  1. 1

    Place the charger

    Next to the parking space, on the side of the car’s charging port.

  2. 2

    Choose the power

    3.7, 7.4 kW or more, depending on the car and the service.

  3. 3

    Draw the route

    From the load center to the charger.

  4. 4

    Generate and export

    Individual circuit at 125 %, ready for your electrician’s quote.

Frequently asked questions

What breaker for a 32 A charger?
40 A: the breaker must be at least 125 % of the charging current, and 40 A is the next standard size above 32 × 1.25 = 40 A.
What wire size for a 40 A EV circuit?
Typically 8 AWG copper NM-B, depending on run length and installation method.
Does an EV charger need GFCI?
A receptacle used for EV charging needs GFCI protection (625.54). A hard-wired charger in a garage or outdoors on a circuit of 50 A or less is also covered by 210.8(F); some jurisdictions accept the charger’s built-in protection instead, so ask your inspector.
Are there incentives for home chargers?
Federal, state and utility incentives change often. Check current programs, for example on the Department of Energy’s Alternative Fuels Data Center.

Official sources

Related guides

Generate a load center from your floor planNEC electrical plan for a house

Build your electrical plan online

Import your PDF plan, drop the electrical symbols and export a clean document to share.

Create a free accountTry without an account