The wire must be rated for the circuit breaker, which is sized at 125% of the charger current. As a general guide with copper conductors, a 40 A circuit (32 A charger) often uses 8 AWG, a 50 A circuit (40 A charger, including NEMA 14-50) often uses 6 AWG, and a 60 A circuit (48 A charger) uses 6 AWG or larger depending on cable type. Cable type, insulation temperature rating, run length and the terminal ratings on the breaker and charger all change the answer, so a licensed electrician should do the final sizing under the National Electrical Code.
Orientation Chart (Copper)
| Charger current | Breaker | Typical copper wire* |
|---|---|---|
| 16 A | 20 A | 12 AWG |
| 24 A | 30 A | 10 AWG |
| 32 A | 40 A | 8 AWG |
| 40 A (NEMA 14-50) | 50 A | 6 AWG |
| 48 A | 60 A | 6 AWG or 4 AWG depending on method |
*Not a design. NM-B (Romex) cable is limited to the 60°C column in many cases, which can require a larger size than THHN in conduit.
What Changes the Size
- Cable type: NM-B vs individual conductors in conduit.
- Long runs: voltage drop may justify upsizing.
- Aluminium conductors: need larger sizes and correct terminations.
- Future-proofing: many electricians pull wire for 60 A even if the charger uses 40 A today.
Match Charger and Circuit
Chargers with adjustable current let you match whatever circuit exists. The EVDANCE EV-ACT5006T 48A Level 2 wall charger is set to its circuit at installation; the EVDANCE EV-ACS4005T 40A NACS portable charger offers 16–40 A steps. See also what size breaker for an EV charger.
Frequently Asked Questions
What gauge wire for a NEMA 14-50?
Commonly 6 AWG copper on a 50 A circuit, subject to cable type and code.
What wire for a 48 A charger?
Wire rated for 60 A, often 6 AWG THHN in conduit or larger for NM-B.
Can I use 8 AWG for a 50 A breaker?
Usually not; wire must be rated for the breaker.
Related Reading
Key Takeaways
- Wire size follows the breaker, which is 125% of charger current.
- Typical copper: 8 AWG for 40 A, 6 AWG for 50 A.
- Cable type and run length can require larger wire.