Wire Sizing

Wire Size for HVAC Unit — 50 Amp 150 Feet

Pre-calculated NEC-compliant wire size for 50 amps at 150 feet on a 240V single-phase circuit. Immediate answer below.

Recommended Wire Size

Copper

4 AWG

Voltage drop: 1.93% (4.62V)

Voltage at load: 235.4V

Controlling factor: Voltage Drop (3% limit)

Aluminum

3 AWG

Voltage drop: 2.52% (6.05V)

Voltage at load: 234V

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	47.1V	19.63%	192.9V
12 AWG	20A	29.7V	12.38%	210.3V
10 AWG	30A	18.6V	7.75%	221.4V
8 AWG	50A	11.67V	4.86%	228.3V
6 AWG	65A	7.37V	3.07%	232.6V
4 AWGREC	85A	4.62V	1.93%	235.4V
3 AWG	100A	3.68V	1.53%	236.3V
2 AWG	115A	2.91V	1.21%	237.1V
1 AWG	130A	2.31V	0.96%	237.7V
1/0 AWG	150A	1.83V	0.76%	238.2V
2/0 AWG	175A	1.45V	0.6%	238.5V
3/0 AWG	200A	1.15V	0.48%	238.9V
4/0 AWG	230A	0.91V	0.38%	239.1V
250 kcmil	255A	0.77V	0.32%	239.2V
300 kcmil	285A	0.64V	0.27%	239.4V
350 kcmil	310A	0.55V	0.23%	239.4V
400 kcmil	335A	0.48V	0.2%	239.5V
500 kcmil	380A	0.39V	0.16%	239.6V

Table shows all standard AWG/kcmil sizes for 50A at 150 ft on 240V (copper). Green check = meets both ampacity and 3% voltage drop. REC = smallest compliant size.

Key Considerations

For a 50A 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 50 amp service at 150 feet?▾

For a 50A/240V circuit at 150 feet, use 4 AWG copper (1.93% drop) or 3 AWG aluminum. This keeps voltage drop within the NEC-recommended 3% limit.

Can I use aluminum wire for a 50 amp circuit?▾

Yes. Aluminum wire is a cost-effective alternative for larger circuits. For 50A at 150 feet, use 3 AWG aluminum (2.52% 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 50A 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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Different voltage, three-phase, or custom max drop percentage? Use our interactive calculator.

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