What Gauge Wire for 30 Amps?
30 amp circuits are common in RVs, boats, and medium off-grid systems. At 12V, 30 amps delivers 360 watts. This is also the standard shore power rating for smaller RVs.
10ft Run
10 AWG
25ft Run
8 AWG
50ft Run
6 AWG
100ft Run
4 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
2 AWG
For 30A at 25ft (12V, 3% max drop)
Power
360W
Actual Voltage Drop
2.0%
(0.24V)
Alternative Gauges
Fuse Recommendation
Use a 40A 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 30A Circuits
- •RV shore power connections (30A)
- •Medium inverters (300-500W)
- •Trolling motors
- •DC water heater elements
- •Large DC refrigerator/freezers
Wire Sizing Tips
- •10 AWG is minimum for 30A, suitable only for very short runs
- •RV 30A shore power uses 10 AWG on typical 25ft cords
- •For battery cables at 30A, 8 AWG minimum, 6 AWG preferred
- •Use hydraulic crimpers for large gauge wire - not hand tools
- •Install a 40A fuse or breaker for 30A circuits
Key Considerations
- ⚠30A RV outlets use TT-30 plugs, not standard household outlets
- ⚠AC and DC have different wire sizing requirements
- ⚠Marine applications require different standards (ABYC)
Frequently Asked Questions
What gauge wire for 30 amps?
10 AWG handles 30 amps for very short runs (under 10ft). For typical installations, use 8 AWG (up to 25ft) or 6 AWG (up to 50ft). Battery cables often use 6 AWG or larger.
Is 10 AWG good enough for 30 amp RV?
10 AWG is standard for RV 30A shore power cords up to 25ft at 120V AC. But for 12V DC applications at 30A, 10 AWG is marginal - use 8 AWG or heavier for reliability.
What size breaker for 30 amp circuit?
Use a 30A breaker or fuse for circuits designed to run at 30A continuous. If protecting equipment rated for less, size the breaker to protect the weakest component.