AWG 10 voltage drop calculator
Voltage drop is current times the resistance of the round trip. For AWG 10 the resistance comes straight from the gauge definition and the conductor resistivity.
A
V
Voltage drop
1.710%
- Voltage lost in the cable
- 3.9322 V
- Voltage at the load
- 226.068 V
- Power lost as heat
- 78.64
- Resistance per metre
- 0.003 276 85 ohm/m
- Conductor area
- 5.261 15 mm2
- Longest run within 3% drop
- 52.64
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 - (10)) / 39) = 2.588 19
- Conductor area = pi * 2.588 19^2 / 4 = 5.261 15
- Resistance per metre = 1.724e-8 / (5.261 15 * 1e-6) * (1 + 0.00393 * (20 - 20)) = 0.003 276 85
- Voltage lost in the cable = 2 * 20 * 0.003 276 85 * 30 = 3.932 22
- Voltage drop = 3.932 22 / 230 * 100 = 1.709 66
- Voltage at the load = 230 - 3.932 22 = 226.068
- Power lost as heat = 3.932 22 * 20 = 78.6443
- Longest run within 3% drop = 0.003 276 85 > 0 && 20 > 0 ? 230 * 0.03 / (2 * 20 * 0.003 276 85) : 0 = 52.6421
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.