What size wire for a 40 amp range?

Start with 8 AWG copper for an ordinary 40 A range circuit, then follow the appliance instructions and check voltage drop for a long run.

Can I run an EV charger on a 40 amp circuit?

A 32 A continuous charger produces a 40 A sizing load: 32 A × 1.25 = 40 A. The charger must be set and listed for that circuit, and the conductor still has to pass the installation's ampacity and distance checks.

Is 8 gauge wire enough for 40 amps?

Yes, under ordinary conditions when the wiring method and termination rating support the applicable ampacity column. Heat, bundled conductors, and long distance can require a larger conductor.

🔌 What Size Wire for a 40 Amp Breaker?

🇨🇦 Canadian version

The short answer

Use 8 AWG copper for an ordinary 40 A circuit. Unlike the smaller branch-circuit sizes, the answer now depends directly on the allowed temperature column and the wiring method.

The verified ampacity table gives #8 copper 40 A in the 60°C column and 50 A in the 75°C column. That makes #8 the minimum at ordinary conditions in either case, but the available headroom is different. Ampacity Check tool.

The 60°C and 75°C split

Distance changes the answer

Minimum size at 240 V, sized at the full 40 A and kept at or under 3% voltage drop (one-way distance):

40 A at 240 V

Material	50 ft	100 ft	150 ft	200 ft	250 ft	300 ft
Copper	8	8	6	4	4	3
Aluminum	8	6	4	3	2	1

Wire Size calculator

Common 40-amp jobs

A range is the classic 40 A circuit. A 32 A continuous EV load also lands on a 40 A circuit because 32 A × 1.25 = 40 A; confirm the charger's setting and installation instructions.

Worked example: 40 A at 240 V over 150 feet

Our verified calculator selects #6 copper (26,240 circular mils): 2 × 12.9 × 40 × 150 ÷ 26,240 = 5.90 V, or 2.46% of 240 V. #8 passes ampacity but does not meet the 3% drop target at this distance.

Wire Size calculator · Ampacity Check tool

40-amp wire size FAQ

What size wire for a 40 amp range?: Start with 8 AWG copper for an ordinary 40 A range circuit, then follow the appliance instructions and check voltage drop for a long run.
Can I run an EV charger on a 40 amp circuit?: A 32 A continuous charger produces a 40 A sizing load: 32 A × 1.25 = 40 A. The charger must be set and listed for that circuit, and the conductor still has to pass the installation's ampacity and distance checks.
Is 8 gauge wire enough for 40 amps?: Yes, under ordinary conditions when the wiring method and termination rating support the applicable ampacity column. Heat, bundled conductors, and long distance can require a larger conductor.