What Gauge Wire for 50 Amps?
The 50 amp circuit is the workhorse of heavy residential loads: RV pedestals, electric ranges, EV chargers, welders, and hot tubs. The answer is 6 AWG copper, but EV chargers and long runs each add a wrinkle worth understanding before you pull wire.
A 50 amp circuit needs 6 AWG copper (55 amps at 60C, protected by a 50 amp breaker per NEC 240.4(B)) or 4 AWG aluminum. Continuous loads like EV chargers are limited to 40 amps. Drop math: a 200 ft run at 40 amps on 6 AWG copper drops 7.87 volts (3.28 percent), so 4 AWG brings it to 4.94 volts (2.06 percent).
The short answer: 6 AWG copper
6 AWG copper is the standard wire for a 50 amp circuit. It is rated 55 amps at the 60 degree column, and NEC 240.4(B) lets you protect a 55 amp conductor with the next standard breaker size up, which is 60 amps, but the overwhelmingly common and correct choice for a 50 amp circuit is a 50 amp breaker on 6 AWG copper. The aluminum equivalent is 4 AWG (65 amps at 75 degrees).
Where 50 amp circuits show up
RV pedestal outlets (NEMA 14-50, 240 volt), electric ranges and cooktops, EV chargers, welders, and hot tubs or spas. Most of these are 240 volt with a neutral: the RV plug and the range need 120 volts for controls and accessories alongside the 240 volt heating elements, so they run 6/3 cable (two hots, neutral, ground). A pure 240 volt welder circuit with no neutral can use 6/2.
EV chargers and the 80 percent rule
EV charging is a continuous load by definition: a car can easily charge for 3 hours or more. NEC 625 sizes EV supply equipment at 125 percent of the load, which is the same as limiting the charger to 80 percent of the circuit. On a 50 amp circuit, that means a 40 amp maximum charge rate (9.6 kW at 240 volts). If you want a 48 amp charger (11.5 kW), you need a 60 amp circuit on 6 AWG copper at 75 degree terminations. This is the single most common 50 amp sizing mistake: buying the 48 amp charger and putting it on a 50 amp breaker.
Distance math: when 6 AWG is not enough
Take a 240 volt, 40 amp continuous load on 6 AWG copper (VD = 2 x 12.9 x I x L / CM):
100 foot one-way run: 2 x 12.9 x 40 x 100 / 26240 = 103,200 / 26,240 = 3.93 volts, or 1.64 percent. Fine.
200 foot one-way run: 2 x 12.9 x 40 x 200 / 26240 = 206,400 / 26,240 = 7.87 volts, or 3.28 percent. Over the 3 percent guidance. Upsize to 4 AWG: 206,400 / 41,740 = 4.94 volts, or 2.06 percent.
In aluminum, 4 AWG on the same 200 foot run gives 2 x 21.2 x 40 x 200 / 41740 = 339,200 / 41,740 = 8.13 volts, or 3.39 percent, still over, so step to 3 AWG aluminum: 339,200 / 52,620 = 6.45 volts, or 2.69 percent. RV pedestals at the back of a large property are exactly the case where this math earns its keep.
A note on safety: wire sizing involves the National Electrical Code, breaker rules, and local amendments. The examples below are planning estimates. Have a licensed electrician review any real installation before you buy wire or pull a permit.
Skip the arithmetic
Wiring a 50 amp RV outlet or EV charger? Enter your run length and load to check the drop on 6 AWG or 4 AWG before you trench or pull cable.
50 amp wire size questions
Can I use 8 gauge wire for 50 amps?
No. 8 AWG copper is rated 40 amps at the 60 degree column and 50 amps at 75 degrees, but the small-conductor and termination rules make it unsuitable as a general 50 amp branch circuit wire. Use 6 AWG copper minimum for 50 amps.
What size breaker do I need for 6 gauge wire?
50 amps is the standard pairing for 6 AWG copper on a branch circuit. 6 AWG is rated 55 amps at 60 degrees, and the 50 amp breaker protects it with margin. Do not put a 60 amp breaker on 6 AWG unless every termination is 75 degree rated and the load calculation supports it.
What wire do I need for a 50 amp RV plug?
A NEMA 14-50 RV outlet is 240 volt, 50 amp with a neutral: run 6/3 cable with ground (two hots, neutral, bare ground) on a 50 amp double-pole breaker. If the pedestal is a long run from the panel, check voltage drop; 200 feet at full load needs 4 AWG copper.
Is 6 AWG enough for a 50 amp EV charger?
Only if the charger is set to 40 amps maximum. EV charging is a continuous load, so NEC limits it to 80 percent of the circuit: 40 amps on a 50 amp circuit. A 48 amp charger needs a 60 amp circuit instead.
Copper or aluminum for a 50 amp feeder?
Both work: 6 AWG copper or 4 AWG aluminum. Copper is the default for branch circuits and short runs. Aluminum saves real money on long feeder runs to a subpanel or pedestal, but it needs lugs listed for aluminum, anti-oxidant compound, and proper torque. For a 200 foot run, 3 AWG aluminum beats 6 AWG copper on voltage drop.