Wire size guide
⚠ Safety first. High-voltage, high-current battery systems can cause fire, severe burns and electrocution. Builds involving these systems should be done or inspected by a qualified professional. This page is general information only, not engineering advice; follow your parts makers' instructions and local codes.
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Ampacity table (copper, 75°C insulation)
| Gauge | Ampacity | DC resistance (Ω/1000 ft) |
|---|---|---|
| 14 AWG | 20 A | 3.07 |
| 12 AWG | 25 A | 1.93 |
| 10 AWG | 35 A | 1.21 |
| 8 AWG | 50 A | 0.764 |
| 6 AWG | 65 A | 0.491 |
| 4 AWG | 85 A | 0.308 |
| 3 AWG | 100 A | 0.245 |
| 2 AWG | 115 A | 0.194 |
| 1 AWG | 130 A | 0.154 |
| 1/0 AWG | 150 A | 0.122 |
| 2/0 AWG | 175 A | 0.0967 |
| 3/0 AWG | 200 A | 0.0766 |
| 4/0 AWG | 230 A | 0.0608 |
Sources: ampacity from NFPA 70 (National Electrical Code) Table 310.16, copper, 75°C column, not more than three current-carrying conductors, 30°C ambient. Resistance from NEC Chapter 9 Table 8 (uncoated copper, 75°C). NEC tables are for building wiring; fine-strand welding/battery cable with higher-temp insulation may be rated higher by its maker — use the maker's rating. Peak (launch) currents above these values are short-duration; size for continuous current and protect every cable with a correctly rated fuse. Voltage drop target here: ≤3% round trip.