Home Charger Amp & Breaker Calculator
Find the amp draw, breaker size and wire gauge needed to install a home Level 2 EV charger.
The 80% rule
EV charging is a “continuous load” under the U.S. National Electrical Code, which means the circuit must be rated for 125% of the actual draw — or equivalently, the charger can only use 80% of the breaker. A 40 A breaker safely carries a 32 A continuous EV load.
Common home chargers
- 16 A / ~3.8 kW: needs a 20 A circuit, 12 AWG wire.
- 32 A / ~7.4 kW: needs a 40 A circuit, 8 AWG wire.
- 40 A / ~9.6 kW: needs a 50 A circuit, 6 AWG wire.
- 48 A / ~11.5 kW: needs a 60 A circuit, 6 AWG wire — Tesla Wall Connector territory.
Wire gauges above assume a copper feeder of roughly 50 feet or less. Longer runs need thicker wire to avoid voltage drop, and aluminium wire is sized differently.
This is a planning estimate, not an installation guide. EV charger installs need a dedicated circuit, the right GFCI protection, and must meet your local electrical code. Always have the work done (or at least inspected) by a licensed electrician.