What Size Wire for 50 Amp
6 AWG copper for most 50-amp circuits, with real caveats.
Compiled by DIY Repair Guide · reviewed 2026-09-05 ·how we research these
The short answer for a 50-amp branch circuit is <strong>6 American Wire Gauge (AWG) copper</strong>. That is what an electric range, a large air conditioner or a welder outlet will normally be run in.
The longer answer matters more than usual here, because 50-amp circuits are where three complications converge: aluminum is common at this size, distance starts to bite, and the rules for a feeder to a subpanel differ from those for a branch circuit to an appliance.
The Basic Answer
At 60°C terminations, which is what most residential devices and breakers are rated for.
- Cable type follows the location. 6/3 NM-B (Romex) for a dry interior run, THHN in conduit where conduit is required, underground feeder cable (UF-B) for direct burial to a detached structure.
- You need the right conductor count. A modern range or dryer circuit needs two hots, a neutral and a ground, 6/3 with ground, not 6/2.
- Never undersize and rely on the appliance. The breaker protects the wire, so 8 AWG on a 50-amp breaker means the cable can overheat before the breaker ever trips.
| Conductor | Size for 50 A | Notes |
|---|---|---|
| Copper | 6 AWG | The standard answer |
| Aluminum / copper-clad aluminum | 4 AWG | Two sizes up, standard for feeders |
| Ground (copper) | 10 AWG | Equipment grounding conductor |
| Ground (aluminum) | 8 AWG |
Distance and Voltage Drop
At 50 amps, resistance in the conductor starts to matter well within the length of a normal house. The usual design target is to keep voltage drop under 3 percent.
Most 50-amp circuits are 240 V, which helps considerably. At double the voltage the same power draws half the current, so drop accumulates more slowly than it would on a 120 V run.
| Run length | Copper size | Aluminum size |
|---|---|---|
| Up to about 60 ft | 6 AWG | 4 AWG |
| 60–100 ft | 4 AWG | 2 AWG |
| 100–150 ft | 3 AWG | 1 AWG |
| 150–200 ft | 2 AWG | 1/0 AWG |
A detached garage or workshop is where this almost always applies. A 50-amp feeder run 120 feet to an outbuilding is a 4 AWG copper job, not 6 AWG, and skipping that step gives you tools that run hot and lights that dip when the compressor starts.
Branch Circuit or Feeder? the Rule Differs
This is the distinction that causes most confusion at 50 amps, because the same wire size can be correct or incorrect depending on what it is feeding.
A branch circuit runs from the panel to one appliance or outlet. A range, a hot tub, a welder receptacle. It is sized straightforwardly from the ampacity tables: 6 AWG copper for 50 amps.
A feeder runs from the main panel to a subpanel. The NEC contains an allowance for dwelling services and feeders that lets a conductor carry more than its table ampacity would suggest, on the basis that a whole dwelling never runs everything at once. This is why you sometimes see 6 AWG copper feeding a 60-amp subpanel and it is genuinely compliant, where the same wire on a 60-amp branch circuit would not be.
The practical point: do not copy a wire size you saw used for a subpanel and apply it to an appliance circuit, or the reverse. Tell the supplier which you are running.
What Actually Runs on 50 Amps
The load determines the breaker, and the breaker determines the wire.
| Appliance | Typical breaker | Copper wire |
|---|---|---|
| Electric range, 40–50 A | 50 A | 6 AWG |
| Electric range, larger | 50–60 A | 6–4 AWG |
| Electric dryer | 30 A | 10 AWG |
| Tankless electric water heater | 60–150 A | 4 AWG and up, often multiple circuits |
| Hot tub or spa | 50–60 A | 6 AWG, ground-fault circuit interrupter (GFCI) protected |
| Welder | 50 A | 6 AWG |
| EV charger, 40 A continuous | 50 A | 6 AWG |
| Subpanel to garage | 50–60 A feeder | 6 AWG copper or 4 AWG aluminum |
EV Chargers and the 80 Percent Rule
An EV charger is a continuous load, meaning it runs at full draw for three hours or more. The NEC requires continuous loads to be limited to 80 percent of the circuit rating.
So a 50-amp circuit supports a charger set to 40 amps continuous, not 50. This is why a 48-amp charger needs a 60-amp circuit, which in turn needs 6 AWG copper at minimum and 4 AWG over any distance.
Getting this wrong is common, because the charger is often specified by its output while the circuit is specified by its breaker. Work out the continuous draw first, divide by 0.8, and size the breaker from that number.
Hot tubs and spas require GFCI protection and a disconnect within sight of the equipment. EV charger installations frequently require a permit and, in many jurisdictions, a load calculation to confirm the service can carry it. Neither is a job to do unpermitted.
Aluminum at This Size Is Normal
Aluminum branch wiring in the small sizes has a poor reputation for good reason. Aluminum feeders at 4 AWG and larger are a different matter. They are standard, widely used, and perfectly sound when terminated properly.
What "properly" means is specific: terminals rated for aluminum (marked AL or CU-AL), an antioxidant compound applied to the conductor, and connections torqued to the manufacturer's specification with a torque screwdriver rather than tightened by feel. Aluminum creeps under pressure, so an untorqued connection loosens over time.
The trade-off is cost against size. Aluminum is markedly cheaper for the same ampacity but two gauge sizes larger, which means bigger conduit and tighter bends.
Before You Buy the Cable
Five checks that prevent the common expensive mistakes.
- Confirm the actual load, not the breaker someone suggested. Continuous loads need the 80 percent calculation.
- Measure the run, following the actual route including vertical drops rather than the straight-line distance.
- Check your panel has capacity. A 50-amp addition to a 100-amp service often needs a load calculation, and sometimes a service upgrade.
- Check the termination temperature rating on both the breaker and the device. Residential terminations are usually 60°C, and using the 75°C column when the equipment is rated 60°C undersizes the wire.
- Confirm conductor count. Two hots, neutral and ground for a range. Some loads need no neutral at all, which changes the cable you buy.
Common questions
What size wire do I need for a 50 amp breaker?
6 AWG copper for a standard branch circuit at 60°C terminations, or 4 AWG aluminum. Over roughly 60 feet, go up a size to keep voltage drop under 3 percent.
Can I use 8 gauge wire on a 50 amp circuit?
No. 8 AWG copper is rated for 40 amps at 60°C terminations. A 50-amp breaker on it means the cable can overheat inside a wall without the breaker ever tripping, which is exactly what the breaker exists to prevent.
What size wire for a 50 amp EV charger?
A 50-amp circuit supports 40 amps continuous, so 6 AWG copper. If the charger draws 48 amps continuous it needs a 60-amp circuit instead, which is 6 AWG at minimum and 4 AWG over distance.
What size wire for a 50 amp subpanel 100 feet away?
Around 4 AWG copper or 2 AWG aluminum at that distance, to stay within a 3 percent voltage drop. Feeders also follow different sizing rules from branch circuits, so tell the supplier it is a subpanel feeder.
Is aluminum wire safe for a 50 amp circuit?
Yes at this size, and it is standard for feeders. It needs AL or CU-AL rated terminals, antioxidant compound, and connections torqued to specification rather than tightened by feel, because aluminum creeps under pressure.