Irrigation & Lighting Division

Voltage Loss for Copper Wire (Metric)

The voltage losses in the chart below were calculated using Ohm's Law, and are theoretical. Safety margin should be built into the design to take into consideration deterioration of wire splices, power brownouts, etc.

VOLTAGE LOSS PER 100m OF WIRE RUN
(VOLTS PER 200m OF WIRE)
FLOW
(AMPS)
WIRE SIZE (mm2)
1.5 2.5 4.0
0.1 0.21 0.14 0.08
0.2 0.43 0.27 0.17
0.3 0.64 0.41 0.25
0.4 0.86 0.54 0.34
0.5 1.07 0.68 0.42
0.6 1.29 0.81 0.51
0.7 1.50 0.95 0.59
0.8 1.72 1.08 0.68
0.9 1.93 1.22 0.76
1.0 2.15 1.35 0.85
2.0 4.29 2.70 1.69
3.0 6.44 4.05 2.54
4.0 8.58 5.41 3.38
5.0 10.73 6.76 4.23
6.0 12.87 8.11 5.08
7.0 15.02 9.46 5.92
8.0 17.16 10.81 6.77
9.0 19.31 12.16 7.62
10.0 21.45 13.51 8.46
 
COPPER WIRE RESISTANCE
(OHMS PER 100m OF WIRE)
WIRE SIZE (mm²)
1.5 2.5 4.0
1.073 0.676 0.423