Spannungsabfall-Rechner — Formel
## Voltage Drop Formula
**Vdrop = 2 x K x I x D / CM**
K is 10.8 for copper (12.9 for aluminum), I is current in amps, D is one-way distance, and CM is the wire cross-section in circular mils. The factor of 2 accounts for the round-trip path.
**Vdrop = 2 x K x I x D / CM**
K is 10.8 for copper (12.9 for aluminum), I is current in amps, D is one-way distance, and CM is the wire cross-section in circular mils. The factor of 2 accounts for the round-trip path.
Lösungsbeispiel
20A on 12 AWG (6,530 CM) copper over 75 ft at 120V.
- Vdrop = 2 x 10.8 x 20 x 75 / 6530 = 4.96V
- Percentage = 4.96 / 120 x 100 = 4.14%
- Voltage at load = 120 - 4.96 = 115.0V
- This exceeds 3%; consider upsizing to 10 AWG.