What Size Wire for 100 Amps? Breaker & Wire Chart
100 Amp Service Wire Chart
| Wire Material | Size | Ampacity (75°C) | Conduit Size | Cost/ft (approx) |
|---|---|---|---|---|
| Copper | 1/0 AWG | 125A | 1.5 inch | $2.50–3.50 |
| Aluminum | 2/0 AWG | 115A | 2 inch | $1.00–1.80 |
| Copper (continuous) | 1/0 AWG | 125A | 1.5 inch | $2.50–3.50 |
| Aluminum (continuous) | 3/0 AWG | 135A | 2 inch | $1.50–2.20 |
Frequently Asked Questions
What size wire for 100 amps?
1/0 AWG copper (125A at 75°C) or 2/0 AWG aluminum (115A at 75°C) per NEC Table 310.16. For continuous loads: 100A × 1.25 = 125A → use 1/0 copper or 3/0 aluminum.
What size wire for a 100 amp sub panel?
1/0 AWG copper or 2/0 AWG aluminum for the feeder. Use 1.5 inch conduit for copper, 2 inch for aluminum. The sub-panel also needs a 4-wire feed: 2 hots + 1 neutral + 1 ground.
Can I run 100 amps on 2 AWG wire?
No. 2 AWG copper is rated for 95 amps (60°C) or 115 amps (75°C). At 75°C it technically works, but NEC 240.4(B) limits #2 copper to 100A maximum overcurrent protection. Use 1/0 AWG for a proper 100A installation.
Disclaimer: For preliminary design only. Verify against local codes and professional engineering requirements.