Cable Voltage Drop Calculator
Check the voltage drop on a 12 V or 24 V DC cable run and find the minimum conductor size for your device.
Typically 12, 13.8, 24 or 27.6 V DC.
Check the minimum operating voltage on the device's datasheet.
Results
Voltage drop: 3.44 V (28.7%)
Voltage at the device: 8.56 V
Loop resistance: 3.440 Ω
Minimum conductor size for this limit: 1.43 mm² — nearest standard size 1.5 mm²
Assumes a two-wire copper DC run at 20°C; resistance rises with temperature, so allow some margin. For 230 V AC mains circuits, size cables to AS/NZS 3008.
How it works
Current flows out to the device and back, so the calculator uses twice the one-way length. Loop resistance is that length times the resistivity of copper (0.0172 Ω·mm²/m at 20°C) divided by the conductor's cross-section; the voltage drop is the load current times that resistance. The minimum conductor size is the cross-section that keeps the drop inside your chosen limit.
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