Wire Size Calculator
Find the correct AWG wire gauge for your circuit based on amperage and wire run distance. Follows NEC ampacity guidelines.
How It Works
Find the correct AWG wire gauge for your circuit based on amperage and wire run distance. Follows NEC ampacity guidelines. Enter your values above and click Calculate to get instant results.
Formula
V_drop = 2 × I × R_wire × L | NEC max: 5% voltage drop
Quick Examples
- 20A circuit, 50ft run at 120V → AWG 12 recommended
- 30A circuit, 100ft run at 240V → AWG 10 recommended
Frequently Asked Questions
What AWG should I use for a 20-amp circuit?
NEC requires minimum AWG 12 for 20-amp circuits. For runs over 50 feet, consider AWG 10 to keep voltage drop below 5%.
What is the NEC 5% voltage drop rule?
The National Electrical Code recommends keeping voltage drop to 3-5% maximum. Excessive voltage drop reduces appliance efficiency and can cause overheating.