How far can you run 2/0 AWG wire?

At 20 A on a 120 V single-phase circuit, 2/0 AWG copper stays under 3% voltage drop for about 928 ft one-way. At 240 V the same load reaches roughly 1856 ft, because allowable drop scales with system voltage.

What is the voltage drop of 2/0 AWG wire per 100 feet?

About 0.39 V at 20 A on 120 V single phase, using VD = 2 × K × I × L / cmil with K = 12.9 for copper.

Is 3% voltage drop a code requirement?

It is a recommendation, not a mandatory limit, in most adopted codes: roughly 3% on the branch circuit and 5% total including the feeder. Some local amendments and specifications do make it enforceable, so check what applies to your job.

Does aluminium change the 2/0 AWG numbers?

Yes. Aluminium uses K = 21.2 instead of 12.9, so drop is about 64% higher for the same size and run, and allowable distance falls by roughly the same proportion.

2/0 AWG Voltage Drop — Max Run Length by Load

Voltage drop for 2/0 AWG copper and aluminium: at 20 A on 120 V single phase the 3% limit is reached at about 928 ft one-way. Full table by load, voltage and distance.

Quick answer

2/0 AWG copper reaches 3% voltage drop at about 928 ft one-way carrying 20 A on a 120 V single-phase circuit. At 100 ft the same load drops 0.39 V (0.32%), calculated as VD = 2 × K × I × L / cmil with K = 12.9 for copper and 133,077 circular mils.

3% limit @ 20 A, 120 V

928ft

3% limit @ 20 A, 240 V

1856ft

Drop @ 100 ft, 20 A

0.39V

Ω / 1000 ft (Cu)

0.0779

Maximum one-way run length at 3% drop

Copper 2/0 AWG. Aluminium distances are roughly 62% of these figures.

Load	120 V 1Ø	240 V 1Ø	208 V 3Ø	480 V 3Ø
5 A	3,713 ft	7,427 ft	7,433 ft	17,153 ft
10 A	1,856 ft	3,713 ft	3,716 ft	8,576 ft
15 A	1,237 ft	2,475 ft	2,477 ft	5,717 ft
20 A	928 ft	1,856 ft	1,858 ft	4,288 ft
25 A	742 ft	1,485 ft	1,486 ft	3,430 ft
30 A	618 ft	1,237 ft	1,238 ft	2,858 ft
40 A	464 ft	928 ft	929 ft	2,144 ft
50 A	371 ft	742 ft	743 ft	1,715 ft
60 A	309 ft	618 ft	619 ft	1,429 ft
80 A	232 ft	464 ft	464 ft	1,072 ft
100 A	185 ft	371 ft	371 ft	857 ft

Source & method: Derived from VD = 2 × K × I × L / cmil (1.732 × K × I × L / cmil for three phase), solved for L at 3% of nominal voltage. Run your exact circuit.

Voltage drop by distance at common loads

Distance	10 A	15 A	20 A	30 A
25 ft	0.04%	0.06%	0.08%	0.12%
50 ft	0.08%	0.12%	0.16%	0.24%
75 ft	0.12%	0.18%	0.24%	0.36%
100 ft	0.16%	0.24%	0.32%	0.48%
150 ft	0.24%	0.36%	0.48%	0.73%
200 ft	0.32%	0.48%	0.65%	0.97%
300 ft	0.48%	0.73%	0.97%	1.45%

Percent drop, 120 V single phase, copper.

Published standard

Frequently asked

How far can you run 2/0 AWG wire?: At 20 A on a 120 V single-phase circuit, 2/0 AWG copper stays under 3% voltage drop for about 928 ft one-way. At 240 V the same load reaches roughly 1856 ft, because allowable drop scales with system voltage.
What is the voltage drop of 2/0 AWG wire per 100 feet?: About 0.39 V at 20 A on 120 V single phase, using VD = 2 × K × I × L / cmil with K = 12.9 for copper.
Is 3% voltage drop a code requirement?: It is a recommendation, not a mandatory limit, in most adopted codes: roughly 3% on the branch circuit and 5% total including the feeder. Some local amendments and specifications do make it enforceable, so check what applies to your job.
Does aluminium change the 2/0 AWG numbers?: Yes. Aluminium uses K = 21.2 instead of 12.9, so drop is about 64% higher for the same size and run, and allowable distance falls by roughly the same proportion.

2/0 AWG Voltage Drop — Max Run Length by Load

Maximum one-way run length at 3% drop

Voltage drop by distance at common loads

Frequently asked

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