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.
Frequently asked
Why is the breaker rated higher than the charger's actual amp draw?
Because the US National Electrical Code treats EV charging as a continuous load — the circuit must be rated for 125% of the actual draw, or equivalently the charger can only use 80% of the breaker. A 32 A continuous EV load needs a 40 A breaker.
What is the difference between 16, 32, 40, and 48 A chargers?
16 A (~3.8 kW) = 20 A circuit, 12 AWG wire — adds ~13 mph. 32 A (~7.4 kW) = 40 A circuit, 8 AWG — adds ~26 mph (most common home install). 40 A (~9.6 kW) = 50 A circuit, 6 AWG — adds ~34 mph. 48 A (~11.5 kW) = 60 A circuit, 6 AWG — adds ~41 mph.
Do I need a licensed electrician to install a Level 2 charger?
Yes — anything beyond plugging into an existing NEMA 14-50 needs permitted electrical work. An unlicensed install can void homeowner insurance, fail at sale, and create real fire risk. The cost is typically $400–1,200 for labor plus $50–200 for the permit.
Can I plug a Level 2 charger into an existing dryer outlet?
Possibly — many dryer outlets are NEMA 14-30 (30 A) and work with portable Level 2 chargers capped at 24 A. But check the circuit's actual capacity, avoid running the dryer and charger simultaneously, and ideally have an electrician confirm the wiring can handle continuous EV load.
How long can the wire run be?
The wire-gauge table here assumes a copper feeder of about 50 feet or less. Longer runs need one gauge thicker to avoid voltage drop. Aluminum wire is sized differently. Your electrician calculates this on the site visit.