Wire Sizing

What Size Wire for 80 Amp 100 Feet Away

Pre-calculated NEC-compliant wire size for 80 amps at 100 feet on a 240V single-phase circuit. Immediate answer below.

Recommended Wire Size

Copper

4 AWG

Voltage drop: 2.05% (4.93V)

Voltage at load: 235.1V

Controlling factor: Ampacity (NEC 310.16)

Aluminum

2 AWG

Voltage drop: 2.13% (5.1V)

Voltage at load: 234.9V

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 100 ft.

Wire Comparison Table

Wire Size	Ampacity	V-Drop (V)	V-Drop (%)	V at Load
14 AWG	15A	50.24V	20.93%	189.8V
12 AWG	20A	31.68V	13.2%	208.3V
10 AWG	30A	19.84V	8.27%	220.2V
8 AWG	50A	12.45V	5.19%	227.6V
6 AWG	65A	7.86V	3.27%	232.1V
4 AWGREC	85A	4.93V	2.05%	235.1V
3 AWG	100A	3.92V	1.63%	236.1V
2 AWG	115A	3.1V	1.29%	236.9V
1 AWG	130A	2.46V	1.03%	237.5V
1/0 AWG	150A	1.95V	0.81%	238V
2/0 AWG	175A	1.55V	0.64%	238.5V
3/0 AWG	200A	1.23V	0.51%	238.8V
4/0 AWG	230A	0.97V	0.41%	239V
250 kcmil	255A	0.82V	0.34%	239.2V
300 kcmil	285A	0.69V	0.29%	239.3V
350 kcmil	310A	0.59V	0.24%	239.4V
400 kcmil	335A	0.51V	0.21%	239.5V
500 kcmil	380A	0.41V	0.17%	239.6V

Table shows all standard AWG/kcmil sizes for 80A at 100 ft on 240V (copper). Green check = meets both ampacity and 3% voltage drop. REC = smallest compliant size.

Key Considerations

For a 80A circuit at 100 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 80 amp service at 100 feet?▾

For a 80A/240V circuit at 100 feet, use 4 AWG copper (2.05% drop) or 2 AWG aluminum. This keeps voltage drop within the NEC-recommended 3% limit.

Can I use aluminum wire for a 80 amp circuit?▾

Yes. Aluminum wire is a cost-effective alternative for larger circuits. For 80A at 100 feet, use 2 AWG aluminum (2.13% 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 80A circuit at 100 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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