Wire Sizing

What Size Wire for 30 Amp 50 Feet Away

Pre-calculated NEC-compliant wire size for 30 amps at 50 feet on a 240V single-phase circuit. Immediate answer below.

Recommended Wire Size

Copper

10 AWG

Voltage drop: 1.55% (3.72V)

Voltage at load: 236.3V

Controlling factor: Ampacity (NEC 310.16)

Aluminum

8 AWG

Voltage drop: 1.6% (3.84V)

Voltage at load: 236.2V

Controlling factor: Ampacity (NEC 310.16)

Based on NEC Table 310.16 (75°C column), single-phase, 240V, 3% max voltage drop, one-way distance 50 ft.

Wire Comparison Table

Wire Size	Ampacity	V-Drop (V)	V-Drop (%)	V at Load
14 AWG	15A	9.42V	3.93%	230.6V
12 AWG	20A	5.94V	2.48%	234.1V
10 AWGREC	30A	3.72V	1.55%	236.3V
8 AWG	50A	2.33V	0.97%	237.7V
6 AWG	65A	1.47V	0.61%	238.5V
4 AWG	85A	0.92V	0.39%	239.1V
3 AWG	100A	0.74V	0.31%	239.3V
2 AWG	115A	0.58V	0.24%	239.4V
1 AWG	130A	0.46V	0.19%	239.5V
1/0 AWG	150A	0.37V	0.15%	239.6V
2/0 AWG	175A	0.29V	0.12%	239.7V
3/0 AWG	200A	0.23V	0.1%	239.8V
4/0 AWG	230A	0.18V	0.08%	239.8V
250 kcmil	255A	0.15V	0.06%	239.8V
300 kcmil	285A	0.13V	0.05%	239.9V
350 kcmil	310A	0.11V	0.05%	239.9V
400 kcmil	335A	0.1V	0.04%	239.9V
500 kcmil	380A	0.08V	0.03%	239.9V

Table shows all standard AWG/kcmil sizes for 30A at 50 ft on 240V (copper). Green check = meets both ampacity and 3% voltage drop. REC = smallest compliant size.

Key Considerations

For a 30A circuit at 50 feet on 240V, both ampacity and voltage drop must be satisfied. NEC recommends keeping the total voltage drop (feeder + branch) under 5%, with no more than 3% on either segment alone.

Copper conductors at 75°C column (THHN/THWN-2) are assumed. If using 60°C terminations, derate the ampacity to the 60°C column values. Verify the temperature rating of your terminals.

Frequently Asked Questions

What size wire do I need for a 30 amp service at 50 feet?▾

For a 30A/240V circuit at 50 feet, use 10 AWG copper (1.55% drop) or 8 AWG aluminum. This keeps voltage drop within the NEC-recommended 3% limit.

Can I use aluminum wire for a 30 amp circuit?▾

Yes. Aluminum wire is a cost-effective alternative for larger circuits. For 30A at 50 feet, use 8 AWG aluminum (1.6% voltage drop). Aluminum requires AL-rated connectors and anti-oxidant compound at all terminations.

What happens if the voltage drop exceeds 3%?▾

Voltage drop above 3% reduces equipment efficiency, can cause motors to overheat, and may violate NEC 210.19(A) Informational Note No. 4. For a 30A circuit at 50 feet on 240V, exceeding 3% means the load receives less than 232.8V, which can damage sensitive electronics and shorten appliance lifespan.

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30A / 75 ft

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Need a Custom Calculation?

Different voltage, three-phase, or custom max drop percentage? Use our interactive calculator.

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