What Size Wire for a 50 Amp Breaker? The 6 AWG vs 8 AWG Answer

The quick answer

For a 50 amp circuit, run 6 AWG copper. If you're using aluminum, go to 4 AWG aluminum. Six-gauge copper is the choice that works everywhere — inside NM-B "Romex" cable and inside conduit — so if you want one answer you can't get wrong, that's it.

6 AWG vs 8 AWG: the answer depends on your wire

This is the single most-searched question about 50 amp circuits, and the confusion is understandable. If you look at the ampacity chart, 8 AWG copper shows 50 amps in the 75°C column of NEC Table 310.16. On paper, 8 AWG "makes" 50 amps — so why does everyone say 6?

Because the wire type sets which column you're allowed to read. The catch is right here:

So when is 8 AWG legal for 50 amps? Only when it's a 75°C-rated wire like THHN/THWN, run in conduit, landing on 75°C-rated terminals. In that setup 8 AWG copper hits exactly 50 amps — with zero margin. Because most homes run 50 amp circuits in Romex, and because 6 AWG gives breathing room either way, the practical rule is simple: use 6 AWG copper unless you specifically know your entire path is 75°C-rated conduit and you want the bare minimum.

50 amp wire size chart

Here's every conductor in a 50 amp circuit, with the recommended all-round sizes highlighted:

The "recommended" row is what most electricians actually pull: 6 AWG copper or 4 AWG aluminum. Both carry 50 amps comfortably in any wire type and leave margin for heat and long runs, which is why they're the default even where a smaller wire is technically legal.

What a 50 amp circuit usually powers

A 50 amp circuit is one of the bigger dedicated circuits in a home — bigger than a dryer, roughly the size of a small subpanel. The most common loads are electric ranges and ovens (the classic 50 amp, on a NEMA 14-50), RVs and campers (14-50), EV chargers (14-50 or hardwired), welders (NEMA 6-50), hot tubs and spas, and larger air compressors. Each one comes down to the same two questions: does it need a neutral, and what wire type are you running — which is exactly what the next two sections settle.

A note on EV chargers (the 50 amp / 14-50 combo)

The 14-50 outlet became the default home EV connection, so a lot of 50 amp circuits are really EV circuits — and there's one rule worth knowing. An EV charger is a continuous load under NEC Article 625, which means the circuit can only be worked at 80% of its rating. On a 50 amp breaker that's 40 amps of actual charging, which is exactly why a plug-in 14-50 charger tops out near 40A even though the circuit is rated 50. The wire doesn't change — it's still 6 AWG copper. If your car can accept the full 48 amps, you'd need a 60 amp circuit with larger wire and a hardwired charger instead of a 14-50 plug.

14-50 vs 6-50: neutral or not

Like the smaller circuits, the cable you buy depends on whether the device needs a neutral — and 50 amp gear splits cleanly into two plugs.

• NEMA 14-50 (range, RV, most EV chargers) → 240V, four wires: two hots, a neutral, and a ground → 6/3 with ground.
• NEMA 6-50 (welders, some EV chargers) → 240V, three wires: two hots and a ground, no neutral → 6/2 with ground.
• NEMA 10-50 (legacy 3-prong range) → old configuration with no separate ground; new installs use the 14-50.

What size ground wire for a 50 amp circuit?

The equipment grounding conductor for a 50 amp circuit is 10 AWG copper (or 8 AWG aluminum), set by NEC Table 250.122. It's the same ground size used all the way from 30 up to 60 amps, because 250.122 groups those together. In NM-B cable the ground is already inside and the right size — you only size it separately when pulling individual conductors in conduit.

Long runs and voltage drop

Because 50 amp circuits often feed things far from the panel — a detached garage EV charger, an RV pad, a subpanel — voltage drop matters more here than on a short 15 or 20 amp run. The NEC recommends keeping branch-circuit drop under 3% (an Informational Note under 210.19(A)).

Here's a run that crosses the line, with the math shown:

1. Running 50A at 240V over 150 ft on 6 AWG copper.
2. Voltage drop = 2 × K × I × length ÷ circular mils = 2 × 12.9 × 50 × 150 ÷ 26,240 = 7.37 V.
3. 7.37 V ÷ 240 V = 3.07% — just over the 3% target, so 6 AWG is borderline here.
4. Step up to 4 AWG (41,740 circular mils) and the same run drops to about 1.9% ✓.

For subpanel feeders and detached-building runs, sizing up like this is routine. The Wire Size Calculator runs the numbers for your exact length, load, and material.

Using aluminum for a 50 amp circuit

The aluminum minimum is 6 AWG (50 amps at 75°C), but 4 AWG aluminum is the common, safer pick — it's the standard for 50 amp ranges and feeders and gives real margin on longer runs. As with any aluminum, use terminals and breakers rated for it, apply an antioxidant compound at the connections, and torque the lugs to spec. Aluminum shows up often on 50 amp feeders because the cost savings grow with wire size and distance.

Common 50-amp wiring mistakes

The number-one mistake is putting 8 AWG Romex on a 50 amp breaker — in NM-B cable, 8 AWG is only rated 40 amps, so it's undersized and a genuine hazard. Close behind is reading the 90°C column (8 AWG = 55A) to justify going smaller; your terminals are 60 or 75°C, so that column doesn't apply. Then come the cable mix-ups: using 6/2 where a range or 14-50 outlet needs the neutral in 6/3, or running a neutral to a 6-50 welder outlet that doesn't use one. And on the long runs that 50 amp circuits so often involve, forgetting voltage drop or skipping conduit-derating math.

Frequently asked questions

Dr. Artie Vance

Technical reviewer · Ph.D. in Physics, MIT · 14 years' experience · Cross-checked against NEC 2026 & 2026

This guide is for general information based on the National Electrical Code. Local codes and your authority having jurisdiction (AHJ) may differ. Electrical work can be dangerous, so when in doubt, hire a licensed electrician.