What Gauge Wire for 100 Amps?
100 amp circuits are used for large inverters, main battery bank feeds, and high-power DC systems. At 12V, 100 amps delivers 1200 watts. Cable costs increase significantly, so plan runs carefully.
10ft Run
4 AWG
25ft Run
2 AWG
50ft Run
1/0 AWG
100ft Run
2/0 AWG
* Based on 12V DC with 3% voltage drop limit. AC circuits may use smaller wire.
Wire Gauge Calculator
Round trip: 50ft (distance x 2)
Recommended Wire Gauge
3/0 AWG
For 100A at 25ft (12V, 3% max drop)
Power
1200W
Actual Voltage Drop
2.7%
(0.32V)
Alternative Gauges
Fuse Recommendation
Use a 125A fuse (125% of rated current, rounded to standard size)
* Always verify with local electrical codes. This calculator is for reference only.
Complete Wire Gauge Chart (12V DC, 3% Drop)
| Wire Gauge | Max Amps @ 10ft | Max Amps @ 25ft | Max Amps @ 50ft | Max Amps @ 100ft |
|---|---|---|---|---|
| 18 AWG | 5A | 2A | 1A | 0.5A |
| 16 AWG | 8A | 3A | 2A | 1A |
| 14 AWG | 12A | 5A | 3A | 1A |
| 12 AWG | 20A | 8A | 4A | 2A |
| 10 AWG | 30A | 12A | 6A | 3A |
| 8 AWG | 50A | 20A | 10A | 5A |
| 6 AWG | 75A | 30A | 15A | 8A |
| 4 AWG | 120A | 48A | 24A | 12A |
| 2 AWG | 190A | 75A | 38A | 19A |
| 1/0 AWG | 300A | 120A | 60A | 30A |
| 2/0 AWG | 380A | 150A | 75A | 38A |
| 4/0 AWG | 600A | 240A | 120A | 60A |
* Round trip distance (double the one-way distance) is used in calculations.
Common Uses for 100A Circuits
- •Large inverters (1000-2000W)
- •Main battery bank cables
- •Electric forklift/golf cart main feeds
- •Large solar charge controller outputs
- •High-power audio systems
Wire Sizing Tips
- •4 AWG is minimum for 100A, only for very short runs (under 6ft)
- •For battery-to-inverter, use 2 AWG minimum, 1/0 AWG preferred
- •Flexible battery cable is easier to route than solid THHN
- •Use a 150A class-T fuse or ANL fuse for 100A circuits
- •Keep cable runs as short as possible - each foot matters
Key Considerations
- ⚠Class-T fuses are recommended for high-amperage 12V systems
- ⚠Busbars help distribute power from large cables to smaller circuits
- ⚠Cable routing affects system safety - avoid sharp bends
Frequently Asked Questions
What gauge wire for 100 amps at 12V?
4 AWG handles 100 amps for very short runs (under 6ft). For 10ft, use 2 AWG. For 25ft, use 1/0 AWG. Most large inverters use 2 AWG to 4/0 AWG depending on cable length.
Can I use welding cable for 100 amp battery cables?
Yes. Flexible welding cable (often marked 2 AWG or larger) is excellent for battery connections. It's more flexible than standard wire, handles vibration well, and is easy to route.
Why are battery cables so expensive?
Large gauge copper is expensive, and cable prices scale with copper content. 4/0 AWG has about 10x the copper of 4 AWG. Keep runs short to minimize cable costs.