Wire Sizing

What Size Wire for 30 Amp 150 Feet Away

Pre-calculated NEC-compliant wire size for 30 amps at 150 feet on a 240V single-phase circuit. Immediate answer below.

Recommended Wire Size

Copper

8 AWG

Voltage drop: 2.92% (7V)

Voltage at load: 233V

Controlling factor: Voltage Drop (3% limit)

Aluminum

4 AWG

Voltage drop: 1.91% (4.57V)

Voltage at load: 235.4V

Controlling factor: Voltage Drop (3% limit)

Based on NEC Table 310.16 (75°C column), single-phase, 240V, 3% max voltage drop, one-way distance 150 ft.

Wire Comparison Table

Wire Size	Ampacity	V-Drop (V)	V-Drop (%)	V at Load
14 AWG	15A	28.26V	11.78%	211.7V
12 AWG	20A	17.82V	7.43%	222.2V
10 AWG	30A	11.16V	4.65%	228.8V
8 AWGREC	50A	7V	2.92%	233V
6 AWG	65A	4.42V	1.84%	235.6V
4 AWG	85A	2.77V	1.16%	237.2V
3 AWG	100A	2.21V	0.92%	237.8V
2 AWG	115A	1.75V	0.73%	238.3V
1 AWG	130A	1.39V	0.58%	238.6V
1/0 AWG	150A	1.1V	0.46%	238.9V
2/0 AWG	175A	0.87V	0.36%	239.1V
3/0 AWG	200A	0.69V	0.29%	239.3V
4/0 AWG	230A	0.55V	0.23%	239.5V
250 kcmil	255A	0.46V	0.19%	239.5V
300 kcmil	285A	0.39V	0.16%	239.6V
350 kcmil	310A	0.33V	0.14%	239.7V
400 kcmil	335A	0.29V	0.12%	239.7V
500 kcmil	380A	0.23V	0.1%	239.8V

Table shows all standard AWG/kcmil sizes for 30A at 150 ft on 240V (copper). Green check = meets both ampacity and 3% voltage drop. REC = smallest compliant size.

Key Considerations

For a 30A circuit at 150 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 150 feet?▾

For a 30A/240V circuit at 150 feet, use 8 AWG copper (2.92% drop) or 4 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 150 feet, use 4 AWG aluminum (1.91% 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 150 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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Need a Custom Calculation?

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

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