Wire Gauge Calculator
Determine the minimum wire gauge (AWG) for a circuit based on amperage and run length to keep voltage drop within limits.
Max Resistance Allowed
1.800 ohm/kft
Max Resistance Allowed vs Circuit Amperage
सूत्र
## Wire Gauge Selection **CM = 2 x K x I x D / Vdrop** Where K = 10.8 (copper resistivity constant), I is current in amps, D is one-way distance in feet, and Vdrop is the allowable voltage drop in volts. Compare the resulting circular mils to an AWG table to pick the minimum wire size.
हल किया गया उदाहरण
20A circuit, 50 ft run, 120V, 3% max drop.
- 01Allowable drop = 120 x 0.03 = 3.6V
- 02CM = 2 x 10.8 x 20 x 50 / 3.6 = 6,000 CM
- 0312 AWG = 6,530 CM, which satisfies the requirement
- 04Use 12 AWG copper wire.
अक्सर पूछे जाने वाले प्रश्न
What is the NEC voltage drop recommendation?
The NEC recommends no more than 3% voltage drop on branch circuits, and no more than 5% total (feeder plus branch). These are recommendations, not hard code requirements.
Why multiply distance by 2?
Current must travel to the load and return, so the total conductor length is twice the one-way distance.
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