NEC 625 Reference
EV Charger Wire Size Chart
Copper and aluminum conductor, breaker, and ground wire size by EV charger amperage, sized at the NEC 625 continuous-load rule. Covers 16A through 80A chargers, the NEMA 14-50, and the common 40A and 48A installs.
Wire, Breaker, and Ground by Charger Amperage
Conductors are the NEC Table 310.16 75°C column sized to 125% of the charger current; the breaker is the smallest standard rating at or above that value; the ground (EGC) is copper per NEC Table 250.122.
| Charger | 125% (min) | Breaker | Copper | Aluminum | Ground (Cu) | Typical Use |
|---|---|---|---|---|---|---|
| 16A | 20A | 20A | #12 | #10 | #12 | NEMA 6-20, small Level 2 |
| 24A | 30A | 30A | #10 | #8 | #10 | NEMA 14-30 / 6-30 |
| 32A | 40A | 40A | #8 | #6 | #10 | Hardwired 32A EVSE |
| 40A | 50A | 50A | #8 | #6 | #10 | NEMA 14-50 (portable EVSE) |
| 48A | 60A | 60A | #6 | #4 | #10 | Tesla Wall Connector, hardwired |
| 50A | 62.5A | 70A | #6 | #4 | #8 | ChargePoint Home Flex (max) |
| 60A | 75A | 80A | #4 | #3 | #8 | Hardwired 60A EVSE |
| 80A | 100A | 100A | #3 | #1 | #8 | Max residential EVSE |
Copper THHN/THWN-2 terminated at the 75°C column. Verify your terminal temperature rating (NEC 110.14(C)). Long runs may require a larger conductor for voltage drop even when ampacity is met. Always confirm against the manufacturer's installation instructions.
NEMA Plug Reference for Plug-In Chargers
A cord-and-plug Level 2 charger is limited to 80% of its receptacle rating. These are the common EV receptacles and the maximum continuous charger current each supports.
| Receptacle | Circuit | Max Continuous | Copper Wire |
|---|---|---|---|
| NEMA 6-20 | 20A / 240V | 16A | #12 |
| NEMA 14-30 | 30A / 240V | 24A | #10 |
| NEMA 6-50 | 50A / 240V | 40A | #8 |
| NEMA 14-50 | 50A / 240V | 40A | #8 |
Cord-and-plug EVSE requires GFCI protection per NEC 625.54. Hardwired chargers with built-in CCID (like the Tesla Wall Connector) satisfy this without a GFCI breaker.
Why EV Circuits Are Sized at 125%
Per NEC 625.2, electric vehicle supply equipment is a continuous load, meaning it can draw its maximum current for three hours or more. NEC 210.20(A) and 625.42 require conductors and overcurrent protection to be rated at 125% of a continuous load. That is why a 48A charger needs a 60A breaker and 60A-rated wire (48 × 1.25 = 60), not a 50A breaker sized to the raw current.
The chart already bakes in the 125% factor: the “125% (min)” column is the minimum conductor ampacity and the breaker is the smallest standard size at or above it. You size the wire to that value at the 75°C column of NEC Table 310.16, then confirm the run length does not push you larger for voltage drop.
Size a Specific Install
Enter the charger, run length, and panel to get the wire, breaker, ground, GFCI requirement, voltage drop, and a parts list for your exact installation.
Frequently Asked Questions
What size wire for a 48A EV charger?
A 48A EV charger (like the Tesla Wall Connector) needs #6 AWG copper conductors on a 60A breaker. EV charging is a continuous load, so the circuit is sized at 125%: 48 x 1.25 = 60A (NEC 625.42, 210.20(A)). #6 copper is rated 65A at the 75C column of NEC Table 310.16, which covers the 60A requirement. In aluminum, use #4 AWG. For runs over about 50 feet, check voltage drop and consider upsizing.
What size wire for a 50 amp EV charger?
A true 50A continuous charger requires a 70A breaker (50 x 1.25 = 62.5A, rounded up to the 70A standard size) with #6 copper or #4 aluminum. However, most '50 amp' EV setups are actually a 40A charger on a NEMA 14-50 outlet, which is a 50A circuit using #8 copper and a 50A breaker. Confirm whether your 50 is the charger's continuous output or the receptacle rating.
What wire size for a NEMA 14-50 outlet?
A NEMA 14-50 receptacle is on a 50A circuit and takes #8 AWG copper (or #6 aluminum) with a 50A breaker and a #10 copper ground. A portable Level 2 charger plugged into it is limited to 40A continuous (80% of the 50A receptacle). If you want the full 48A from a hardwired charger, run #6 copper on a 60A breaker instead of using a 14-50.
What size ground wire for an EV charger?
The equipment grounding conductor is sized by the breaker rating per NEC Table 250.122. A 20A to 60A EV circuit uses a #10 copper EGC; a 70A to 100A circuit uses #8 copper. The EGC does not carry normal current and is smaller than the circuit conductors. It is separate from the neutral and must land on the ground bar.
Can I use aluminum wire for an EV charger?
Yes. Aluminum is allowed and common for larger EV circuits and longer runs where it saves on material. Size it up from copper: #4 aluminum for a 48A charger versus #6 copper, or #3 aluminum for a 60A charger. Use antioxidant on the terminations and torque to spec. Aluminum also drops more voltage, so check the run length on long garage or detached-structure runs.
Does wire size change for a longer EV charger run?
It can. The chart sizes conductors for ampacity and the 125% continuous-load rule at normal distances. On long runs (roughly 50 feet and up for a 48A charger), voltage drop can force you a size larger even though the ampacity is fine. A 48A charger at the end of a 120-foot run often needs #4 copper instead of #6. Check the run with the voltage drop chart.
Related Calculators
EV Charger Calculator
Full install sizing: wire, breaker, panel capacity, GFCI, voltage drop, and parts list.
Voltage Drop Chart
Maximum copper and aluminum run distances at 3% drop, for long garage and detached runs.
Wire Size Calculator
NEC 310.16 ampacity with derating and terminal temperature enforcement.
Load Calculator
Will the panel take the charger? Run the NEC 220.87 existing-load check before you quote.
Wire sized. Will the panel take it?
The conductor is only half the job. Confirm the service has room for the new load with the NEC 220.87 existing-load method before you commit the install.