What size wire for a 30 amp RV plug?

A TT-30 RV receptacle is 120 V. Start with 10 AWG copper at ordinary distances, then use the 120 V table or calculator for the actual one-way run.

Can 12 gauge wire handle 30 amps?

No. NEC 240.4(D) caps 12 AWG copper at 20 A for ordinary circuits, so it does not pass a 30 A ampacity check.

What size wire does a 30 amp dryer use?

Start with 10 AWG copper for an ordinary 30 A dryer circuit. Check the appliance instructions, cable type, and distance before installation.

🔌 What Size Wire for a 30 Amp Breaker?

🇨🇦 Canadian version

The short answer

Start with 10 AWG copper for an ordinary 30 A circuit. A TT-30 RV receptacle is 120 V, while a typical dryer or water-heater circuit is 240 V; that voltage difference changes long-run sizing.

The verified ampacity table supports #8 aluminum at 30 A under ordinary 75°C termination conditions, so aluminum is included. Confirm the conductor type, terminals, and equipment listing before using it. Ampacity Check tool.

Distance changes the answer

Minimum size at the full 30 A and at or under 3% voltage drop. Distance is one way; the calculator also rejects any size that fails ampacity.

30 A at 240 V — dryer or water heater

Material	50 ft	100 ft	150 ft	200 ft	250 ft
Copper	10	8	8	6	4
Aluminum	8	6	4	4	3

30 A at 120 V — RV TT-30

Material	50 ft	100 ft	150 ft	200 ft	250 ft
Copper	8	6	4	3	2
Aluminum	6	4	2	1	1/0

Wire Size calculator

Common 30-amp jobs

Dryers, water heaters, RV receptacles, and some mini-split or air-conditioning circuits commonly land near this rating. Use the equipment nameplate when it gives a different circuit requirement.

Worked example: 30 A RV receptacle at 100 feet

At 120 V, our verified calculator selects #6 copper (26,240 circular mils): 2 × 12.9 × 30 × 100 ÷ 26,240 = 2.95 V, or 2.46%. The 240 V table is smaller because the same volts lost are half the percentage.

Wire Size calculator · Ampacity Check tool

30-amp wire size FAQ

What size wire for a 30 amp RV plug?: A TT-30 RV receptacle is 120 V. Start with 10 AWG copper at ordinary distances, then use the 120 V table or calculator for the actual one-way run.
Can 12 gauge wire handle 30 amps?: No. NEC 240.4(D) caps 12 AWG copper at 20 A for ordinary circuits, so it does not pass a 30 A ampacity check.
What size wire does a 30 amp dryer use?: Start with 10 AWG copper for an ordinary 30 A dryer circuit. Check the appliance instructions, cable type, and distance before installation.