How many amps can 8 AWG wire carry?
50 A — copper at 75 °C, NEC Table 310.16.
8 AWG copper carries 50 A at 75 °C, 40 A at 60 °C and 55 A at 90 °C under NEC Table 310.16, before derating. Aluminum at the same size is 40 A at 75 °C.
Safety first. These figures are an educational reference before derating, not a code substitute. Verify against the current NEC and have circuits reviewed by a licensed electrician.
8 AWG ampacity — copper vs aluminum
| Material | 60 °C | 75 °C | 90 °C | Breaker cap |
|---|---|---|---|---|
| Copper | 40 A | 50 A | 55 A | — |
| Aluminum | 35 A | 40 A | 45 A | — |
Values are amps at a 30 °C ambient, before derating for temperature or conductor bundling. Most installations must use the 75 °C column regardless of the wire's own rating, because terminals and breakers are rated 75 °C (NEC 110.14(C)).
How far can you run 8 AWG at 50 A?
Ampacity answers whether a conductor will overheat. It says nothing about whether the voltage still arrives at the far end. Past roughly fifty feet, voltage drop is usually what really sets the wire size. These are the longest one-way runs that keep drop within the 3% recommended by the NEC 210.19(A) informational note, for 8 AWG copper carrying 50 A.
| System | Typical use | Max run at 3% | Drop at 100 ft |
|---|---|---|---|
| 120 V | standard receptacle and lighting circuits | 57 ft | 6.28 V |
| 240 V | ranges, dryers, EV chargers, feeders | 115 ft | 6.28 V |
| 12 V DC | automotive, marine, solar and battery runs | 6 ft | 6.28 V |
Single-phase, one-way distance, copper at 20 °C. Aluminum reaches its limit at roughly 60% of these distances for the same size. The 3% figure is a recommendation in an informational note, not a code requirement.
8 AWG wire size — diameter, area and resistance
Diameter
0.1285 in · 3.264 mm
Cross-section
8.366 mm² · 16,510 cmil
Nearest metric size
10 mm² (rounds up)
Copper resistance
0.6282 Ω per 1000 ft @ 20 °C
Aluminum resistance
1.0491 Ω per 1000 ft
Area
16.51 kcmil
Diameter is computed from the ASTM B258 definition d = 0.005 × 92^((36 − n)/39), not read from a rounded table. Resistance uses the annealed-copper constant 10.371 Ω·cmil/ft at 20 °C.
What 8 AWG wire is used for
- 40–50 A circuits
- electric ranges and cooktops
- dryers, A/C condensers, EV chargers
The 8 gauge mistake worth knowing
8 AWG copper is 50 A at 75 °C and 40 A at 60 °C. Romex/NM-B cable is limited to the 60 °C column by 334.80 no matter what its jacket says, so 8 AWG NM-B is a 40 A cable — the single most common overestimate at this size.