Calculadora de Bitola de Fio — Formula
## 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.
**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.
Exemplo Resolvido
20A circuit, 50 ft run, 120V, 3% max drop.
- Allowable drop = 120 x 0.03 = 3.6V
- CM = 2 x 10.8 x 20 x 50 / 3.6 = 6,000 CM
- 12 AWG = 6,530 CM, which satisfies the requirement
- Use 12 AWG copper wire.