AWG 14 voltage drop calculator
Voltage drop is current times the resistance of the round trip. For AWG 14 the resistance comes straight from the gauge definition and the conductor resistivity.
A
V
Voltage drop
4.323%
- Voltage lost in the cable
- 9.9418 V
- Voltage at the load
- 220.058 V
- Power lost as heat
- 198.84
- Resistance per metre
- 0.008 284 85 ohm/m
- Conductor area
- 2.080 91 mm2
- Longest run within 3% drop
- 20.82
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 - (14)) / 39) = 1.627 73
- Conductor area = pi * 1.627 73^2 / 4 = 2.080 91
- Resistance per metre = 1.724e-8 / (2.080 91 * 1e-6) * (1 + 0.00393 * (20 - 20)) = 0.008 284 85
- Voltage lost in the cable = 2 * 20 * 0.008 284 85 * 30 = 9.941 82
- Voltage drop = 9.941 82 / 230 * 100 = 4.322 53
- Voltage at the load = 230 - 9.941 82 = 220.058
- Power lost as heat = 9.941 82 * 20 = 198.836
- Longest run within 3% drop = 0.008 284 85 > 0 && 20 > 0 ? 230 * 0.03 / (2 * 20 * 0.008 284 85) : 0 = 20.8211
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.