What wire gauge do I need for a 20 amp circuit?

A 20-amp circuit requires minimum 12 AWG copper wire (or 10 AWG aluminum). For runs over 75 feet, consider 10 AWG copper to keep voltage drop under 3%.

What wire gauge for a 30 amp circuit?

10 AWG copper wire is required for a 30-amp circuit. For long runs (over 50 feet), use 8 AWG to minimize voltage drop.

What is the NEC ampacity table?

NEC Table 310.15(B)(16) lists the maximum ampacity for conductors based on wire gauge, material (copper/aluminum), and temperature rating (60°C, 75°C, 90°C).

Can I use aluminum wire for home wiring?

Aluminum wire is acceptable for large-gauge feeders (6 AWG and larger) but is not recommended for 15 or 20-amp branch circuits due to connection issues.

What is voltage drop and why does it matter?

Voltage drop is the reduction in voltage over a wire run due to resistance. NEC recommends keeping voltage drop under 3% to ensure proper operation of devices at the end of the circuit.

Circuit Breakers & Panels

NEC 80 Percent Breaker Rule Explained

admin / April 8, 2026

Quick Answer The NEC 80 percent breaker rule is a fundamental electrical code requirement that limits the continuous load on […]