Wire Sizing

Wire Size for Well Pump — 15 Amp 200 Feet

Pre-calculated NEC-compliant wire size for 15 amps at 200 feet on a 120V single-phase circuit. Immediate answer below.

Recommended Wire Size

Copper

6 AWG

Voltage drop: 2.46% (2.95V)

Voltage at load: 117.1V

Controlling factor: Voltage Drop (3% limit)

Aluminum

4 AWG

Voltage drop: 2.54% (3.05V)

Voltage at load: 117V

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 200 ft.

Wire Comparison Table

Wire Size	Ampacity	V-Drop (V)	V-Drop (%)	V at Load
14 AWG	15A	18.84V	15.7%	101.2V
12 AWG	20A	11.88V	9.9%	108.1V
10 AWG	30A	7.44V	6.2%	112.6V
8 AWG	50A	4.67V	3.89%	115.3V
6 AWGREC	65A	2.95V	2.46%	117.1V
4 AWG	85A	1.85V	1.54%	118.2V
3 AWG	100A	1.47V	1.23%	118.5V
2 AWG	115A	1.16V	0.97%	118.8V
1 AWG	130A	0.92V	0.77%	119.1V
1/0 AWG	150A	0.73V	0.61%	119.3V
2/0 AWG	175A	0.58V	0.48%	119.4V
3/0 AWG	200A	0.46V	0.38%	119.5V
4/0 AWG	230A	0.36V	0.3%	119.6V
250 kcmil	255A	0.31V	0.26%	119.7V
300 kcmil	285A	0.26V	0.21%	119.7V
350 kcmil	310A	0.22V	0.18%	119.8V
400 kcmil	335A	0.19V	0.16%	119.8V
500 kcmil	380A	0.15V	0.13%	119.8V

Table shows all standard AWG/kcmil sizes for 15A at 200 ft on 120V (copper). Green check = meets both ampacity and 3% voltage drop. REC = smallest compliant size.

Key Considerations

For a 15A circuit at 200 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.

For runs exceeding 200 feet, conduit fill becomes important. Verify that the selected wire size fits within the maximum fill allowance of your conduit per NEC Chapter 9, Table 1. Consider upsizing the conduit rather than downsizing the conductor.

Frequently Asked Questions

What size wire do I need for a 15 amp service at 200 feet?▾

For a 15A/120V circuit at 200 feet, use 6 AWG copper (2.46% 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 200 feet, use 4 AWG aluminum (2.54% 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 200 feet on 120V, exceeding 3% means the load receives less than 116.4V, which can damage sensitive electronics and shorten appliance lifespan.

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