Wire Sizing

What Size Wire for 15 Amp 150 Feet Away

Pre-calculated NEC-compliant wire size for 15 amps at 150 feet on a 120V single-phase circuit. Immediate answer below.

Recommended Wire Size

Copper

8 AWG

Voltage drop: 2.92% (3.5V)

Voltage at load: 116.5V

Controlling factor: Voltage Drop (3% limit)

Aluminum

4 AWG

Voltage drop: 1.91% (2.29V)

Voltage at load: 117.7V

Controlling factor: Voltage Drop (3% limit)

Based on NEC Table 310.16 (75°C column), single-phase, 120V, 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	14.13V	11.78%	105.9V
12 AWG	20A	8.91V	7.43%	111.1V
10 AWG	30A	5.58V	4.65%	114.4V
8 AWGREC	50A	3.5V	2.92%	116.5V
6 AWG	65A	2.21V	1.84%	117.8V
4 AWG	85A	1.39V	1.16%	118.6V
3 AWG	100A	1.1V	0.92%	118.9V
2 AWG	115A	0.87V	0.73%	119.1V
1 AWG	130A	0.69V	0.58%	119.3V
1/0 AWG	150A	0.55V	0.46%	119.5V
2/0 AWG	175A	0.44V	0.36%	119.6V
3/0 AWG	200A	0.34V	0.29%	119.7V
4/0 AWG	230A	0.27V	0.23%	119.7V
250 kcmil	255A	0.23V	0.19%	119.8V
300 kcmil	285A	0.19V	0.16%	119.8V
350 kcmil	310A	0.17V	0.14%	119.8V
400 kcmil	335A	0.14V	0.12%	119.9V
500 kcmil	380A	0.12V	0.1%	119.9V

Table shows all standard AWG/kcmil sizes for 15A at 150 ft on 120V (copper). Green check = meets both ampacity and 3% voltage drop. REC = smallest compliant size.

Key Considerations

For a 15A circuit at 150 feet on 120V, 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 15 amp service at 150 feet?▾

For a 15A/120V 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 15 amp circuit?▾

Yes. Aluminum wire is a cost-effective alternative for larger circuits. For 15A 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 15A circuit at 150 feet on 120V, exceeding 3% means the load receives less than 116.4V, which can damage sensitive electronics and shorten appliance lifespan.

Related Wire Size Calculations

15A / 100 ft

What Size Wire for 15 Amp 100 Feet Away

15A / 75 ft

What Size Wire for 15 Amp 75 Feet Away

15A / 50 ft

What Size Wire for 15 Amp 50 Feet Away

15A / 100 ft

Wire Size for Well Pump — 15 Amp 100 Feet

15A / 200 ft

Wire Size for Well Pump — 15 Amp 200 Feet

Need a Custom Calculation?

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

Wire Size Calculator