12v Cable Size Calculator Australia !!install!! Jun 2026

| Current (A) | 2m run (mm²) | 5m run | 10m run | 15m run | 20m run | |-------------|--------------|--------|---------|---------|---------| | 1 | 1.5 | 1.5 | 1.5 | 1.5 | 1.5 | | 3 | 1.5 | 1.5 | 1.5 | 2.5 | 2.5 | | 5 | 1.5 | 1.5 | 2.5 | 4 | 4 | | 10 | 1.5 | 2.5 | 4 | 6 | 10 | | 15 | 2.5 | 4 | 6 | 10 | 16 | | 20 | 2.5 | 4 | 10 | 16 | 25 | | 30 | 4 | 6 | 16 | 25 | 35 | | 40 | 6 | 10 | 25 | 35 | 50 | | 50 | 6 | 16 | 35 | 50 | 70 | | 60 | 10 | 16 | 35 | 50 | 70 |

$$V_drop = \frac2 \times L \times I \times \rhoA$$ 12v cable size calculator australia

Voltage drop is critical at low voltage. A 1V drop on 12V is – enough to make lights dim, pumps slow, or inverters shut down. Australian standards recommend <5% drop for non‑essential circuits, <3% for sensitive or safety equipment. | Current (A) | 2m run (mm²) |

And always: ✅ Fuse at battery ✅ Double the length in your head ✅ Go one size bigger for voltage‑sensitive loads And always: ✅ Fuse at battery ✅ Double

A 1200W inverter on a 12V system draws 100 Amps ( 1200 / 12 = 100 ).