AWG 2 voltage drop calculator
Voltage drop is current times the resistance of the round trip. For AWG 2 the resistance comes straight from the gauge definition and the conductor resistivity.
A
V
Voltage drop
0.267%
- Voltage lost in the cable
- 0.6151 V
- Voltage at the load
- 229.385 V
- Power lost as heat
- 12.30
- Resistance per metre
- 0.000 512 625 ohm/m
- Conductor area
- 33.6308 mm2
- Longest run within 3% drop
- 336.50
Show the working
- Current = 20
- One-way run length = 30
- Supply voltage = 230
- System = 2
- Conductor = 1.724e-8
- Conductor temperature = 20
- diameter_mm = 0.127 * 92^((36 - (2)) / 39) = 6.543 71
- Conductor area = pi * 6.543 71^2 / 4 = 33.6308
- Resistance per metre = 1.724e-8 / (33.6308 * 1e-6) * (1 + 0.00393 * (20 - 20)) = 0.000 512 625
- Voltage lost in the cable = 2 * 20 * 0.000 512 625 * 30 = 0.615 15
- Voltage drop = 0.615 15 / 230 * 100 = 0.267 456
- Voltage at the load = 230 - 0.615 15 = 229.385
- Power lost as heat = 0.615 15 * 20 = 12.303
- Longest run within 3% drop = 0.000 512 625 > 0 && 20 > 0 ? 230 * 0.03 / (2 * 20 * 0.000 512 625) : 0 = 336.503
Values are shown to six significant figures here; the arithmetic itself runs on exact fractions and is only rounded where a number is printed.
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The formula
- single phase or DC: drop = 2 x I x R per metre x one-way length
- three phase: drop = sqrt(3) x I x R per metre x one-way length
- R per metre = rho / area, corrected for temperature
The factor of two on a single-phase run is because the current goes out and comes back. A three-phase drop uses sqrt(3) because the return currents partly cancel.
This is resistive drop only. On long AC runs at high current, cable reactance adds to it.
Warm conductors have more resistance: at 70 degrees Celsius copper is about 20% more resistive than at 20.