Select your charger amperage and installation type to get the exact wire gauge, breaker size, and conduit spec required by the NEC — and what your inspector will verify.
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| EV Charger Output | Circuit Breaker (125% rule) | Min. Wire Gauge (Copper) | Min. Wire Gauge (Aluminum) | Conduit (EMT) | Ground Wire |
|---|---|---|---|---|---|
| 12A (Level 1) | 15A | 14 AWG | 12 AWG | 1/2" | 14 AWG |
| 16A | 20A | 12 AWG | 10 AWG | 1/2" | 12 AWG |
| 24A | 30A | 10 AWG | 8 AWG | 3/4" | 10 AWG |
| 32A | 40A | 8 AWG | 6 AWG | 3/4" | 10 AWG |
| 40A (most popular) | 50A | 6 AWG | 4 AWG | 3/4" | 10 AWG |
| 48A | 60A | 6 AWG | 4 AWG | 3/4" | 10 AWG |
| 60A | 70A* | 4 AWG | 2 AWG | 1" | 8 AWG |
| 80A | 100A | 3 AWG | 1 AWG | 1-1/4" | 8 AWG |
*60A EVSE on a 70A circuit: per NEC 625.42, EVSE rated 60A is treated as a continuous load requiring a 75A circuit in some jurisdictions — verify locally. Wire sizes shown are minimums for runs under 100 ft in conduit at 75°C rating. Upsize one gauge for runs over 100 ft to prevent voltage drop.
EV chargers are classified as continuous loads under the NEC because they operate for 3+ hours without interruption. The continuous load rule requires:
This is the most common reason for inspection failures — undersized wire on a correctly-sized breaker, or a breaker too small for the EVSE's output.
For EV charger circuits in conduit, use THWN-2 rated wire (90°C rating, wet-location rated). This satisfies both indoor and outdoor conduit requirements. THHN wire (not THWN-2) is only rated for dry locations — avoid it for circuits that pass through garages or any potentially damp area.