The direct answer to what AWG for 50 amps depends on your wire material and insulation type, but the universal benchmark for residential and light commercial work is 6 AWG Copper. While 8 AWG Copper is technically code-compliant under specific 75°C terminal conditions, 6 AWG eliminates the risk of violating 60°C termination limits and provides a buffer for voltage drop. If you are using aluminum wire, you must step up to 4 AWG Aluminum.

Quick-Jump Bookmark Guide:
  • Standard 50A Circuit (THHN in conduit): 8 AWG Copper (if 75°C rated) or 6 AWG Copper (foolproof)
  • 50A Circuit using NM-B (Romex): 6 AWG Copper (mandatory due to 60°C NEC rule)
  • 50A Subpanel Feeder (Aluminum): 4 AWG Aluminum (SER or XHHW)
  • 50A Equipment Ground: 10 AWG Copper or 8 AWG Aluminum

The Complete NEC Wire Sizing Chart for 50 Amps

The table below is derived directly from NEC Table 310.16 (formerly 310.15(B)(16)), the definitive standard for copper and aluminum ampacities. To read this table correctly, you must match your wire's insulation type to the correct temperature column. Most modern THHN/THWN-2 wire is rated for 90°C, but you are rarely allowed to use the 90°C column for your final breaker sizing.

NEC Table 310.16 Ampacities (Insulated Conductors, 30°C Ambient)
AWG Size 60°C Column (TW, UF, NM-B) 75°C Column (THW, THWN, USE-2) 90°C Column (THHN, XHHW)
10 AWG 30A 35A 40A
8 AWG 40A 50A 55A
6 AWG 55A 65A 75A
4 AWG 70A 85A 95A
3 AWG 85A 100A 115A

Source: NFPA National Electrical Code (NEC), Table 310.16. Values shown are for Copper conductors. For Aluminum, shift down two AWG sizes (e.g., 6 AWG Copper roughly equals 4 AWG Aluminum).

Which Temperature Column Applies to Your Installation?

The most common mistake DIYers and junior apprentices make is looking at the 90°C column because they bought THHN wire, seeing that 8 AWG is rated 55A, and assuming it is perfectly safe for a 50-amp breaker. This is a code violation in almost all residential scenarios.

The Rule of Termination (NEC 110.14(C)): Your circuit's ampacity is limited by the lowest temperature rating of any component in the chain. This includes the breaker lugs, the receptacle terminals, and the wire insulation.

  • The 60°C Column: Applies if you are using NM-B cable (Romex) or UF-B underground feeder. NEC 334.80 strictly mandates that NM-B ampacity be determined by the 60°C column, regardless of the fact that the individual THHN wires inside the jacket are rated 90°C. Therefore, 8 AWG NM-B is only good for 40A. For a 50A circuit using Romex, you must use 6 AWG.
  • The 75°C Column: Applies to most modern breakers (like Square D QO/Homeline or Eaton BR) and hardwired equipment terminals (like EV chargers or subpanel lugs). If you pull individual THHN/THWN-2 wires through conduit and land them on 75°C rated lugs, 8 AWG is legally rated for exactly 50A.
  • The 90°C Column: You almost never use this column for final ampacity. Its primary legal purpose is to serve as the starting point for derating calculations before you apply the termination temperature limit.
Pro-Tip for the Workbench: Even though 8 AWG THHN in conduit is code-legal for 50A on 75°C terminals, most experienced electricians pull 6 AWG for 50-amp circuits (like ranges, hot tubs, or EV chargers). The physical cost difference over a 50-foot run is roughly $15-$25, but 6 AWG provides a massive margin of safety against loose terminal heating and makes future upgrades to 60A much easier.

How Derating and Voltage Drop Modify Your Base AWG

NEC Table 310.16 assumes you are running wires in an ambient temperature of 30°C (86°F) and that you have no more than three current-carrying conductors in a single raceway. When real-world conditions deviate from this, the table's base values are no longer sufficient.

1. Conduit Bundling (Derating)

Per NEC 310.15(C)(1), if you pull more than three current-carrying conductors through a single conduit, the wires heat each other up, and you must apply a derating multiplier. This is where the 90°C column finally gets used.

Worked Example: You are pulling two 50A circuits (4 current-carrying hot wires, plus a shared neutral and ground) through one 3/4" EMT conduit. Four to six conductors require an 80% derating factor.

  • If you use 8 AWG THHN: The 90°C base ampacity is 55A. 55A x 0.80 = 44A. This is below your 50A breaker. Code violation.
  • If you use 6 AWG THHN: The 90°C base ampacity is 75A. 75A x 0.80 = 60A. After derating, you then check the 75°C termination limit (65A). 60A is the limiting factor, which safely covers your 50A load.

2. Voltage Drop (What the Table Cannot Tell You)

The NEC ampacity tables dictate fire safety (preventing the wire from melting), but they do not guarantee performance. A 6 AWG copper wire will not catch fire at 50 amps, but if you run it 120 feet to a 50-amp EV charger, the voltage drop will exceed the recommended 3% threshold. The equipment may charge slower, overheat, or throw fault codes.

For long runs, you must size the wire for voltage drop, not just thermal ampacity. Using a tool like the Southwire Voltage Drop Calculator, a 50A load at 240V over 100 feet on 6 AWG copper yields a 2.5% drop (acceptable). Push that to 150 feet, and the drop hits 3.8%, requiring you to bump the wire up to 4 AWG Copper to maintain optimal equipment performance.

Frequently Asked Questions About 50 Amp Wire Sizing

Can I use 8 AWG wire on a 50 amp breaker?

Yes, but only if you are using individual conductors in a raceway (like THHN in EMT or PVC) and you can verify that both the breaker lugs and the equipment terminals are explicitly rated for 75°C. If you are using NM-B (Romex) cable, or if the receptacle is only rated for 60°C, 8 AWG is strictly limited to 40A and will be a fire hazard on a 50-amp breaker. When in doubt, use 6 AWG.

What size ground wire do I need for a 50 amp circuit?

According to NEC Table 250.122, the minimum equipment grounding conductor (EGC) for a 50-amp overcurrent device is 10 AWG Copper or 8 AWG Aluminum. Note that if you upsized your hot wires to mitigate voltage drop (e.g., using 4 AWG copper hots for a long EV charger run), NEC 250.122(B) requires you to proportionally increase the size of your ground wire as well to maintain the fault-current clearing path.

How does voltage drop change the AWG for a 50 amp subpanel?

Subpanels often feed continuous loads that draw close to the breaker's maximum capacity. If your 50-amp subpanel feeder is longer than 60 feet, 6 AWG copper (or 4 AWG aluminum) will begin to experience voltage drop that can cause lights on that subpanel to flicker when heavy loads kick in. For a 50-amp subpanel feeder running between 60 and 100 feet, bumping to 4 AWG Copper or 2 AWG Aluminum is the standard professional practice to ensure the 240V/120V split remains stable under load.

Should I use copper or aluminum for a 50 amp EV charger or range?

For short indoor runs (under 50 feet) to an EV charger or electric range, Copper is heavily preferred. It is more flexible, easier to bend into tight junction boxes, and terminates more reliably into standard brass receptacle screws without the need for anti-oxidant paste. However, if you are trenching a 150-foot underground feeder in PVC conduit for a detached garage 50A circuit, Aluminum (USE-2 or XHHW-2) is the smart choice. You will need to use 4 AWG Aluminum instead of 6 AWG Copper, but the material cost savings on a long run will easily exceed $150, offsetting the minor hassle of using larger lugs and torque-rated terminations.