Voltage Drop Tables

277 volts is derived from a 480/277V wye-connected transformer and is the standard voltage for commercial and industrial lighting in the United States. Using 277V for lighting reduces the current draw by more than half compared to 120V, allowing smaller wire sizes and longer circuit runs. LED and fluorescent lighting ballasts designed for 277V operation are standard in commercial construction.

Understanding Voltage Drop at 277V

Voltage drop is the reduction in voltage between the source (panel) and the load (device) caused by the resistance of the conductors. At 277 volts, a 3% voltage drop equals 8.3 volts, meaning the voltage at the load would be 268.7 volts. The NEC recommends keeping voltage drop below 3% for branch circuits and below 5% for the combined feeder and branch circuit. While these are recommendations rather than mandatory requirements, they represent accepted engineering practice and are enforced by most electrical inspectors.

NEC 210.6 permits 277V lighting circuits in commercial and industrial occupancies. Receptacles at 277V require specific configurations to prevent accidental connection of 120V equipment.

Common 277V circuits include: Commercial fluorescent lighting, LED high-bay lighting, parking lot lighting, warehouse lighting, office lighting circuits, industrial lighting. Each of these applications has specific NEC requirements for wire sizing, overcurrent protection, and installation methods. The tables below provide voltage drop values for copper conductors at various distances and amperages, organized by wire gauge, so you can quickly determine whether a specific gauge is adequate for your installation.

Quick Reference: Maximum Distance by Gauge at 277V

The table below shows the maximum one-way distance for each copper wire gauge at common amperages to maintain a voltage drop of 3% or less at 277 volts (single phase). If your run distance exceeds these values, you must use a larger wire gauge.

Gauge	30A Max Dist	50A Max Dist	100A Max Dist	150A Max Dist	200A Max Dist
10 AWG	111 ft	67 ft	33 ft	22 ft	16 ft
8 AWG	178 ft	106 ft	53 ft	35 ft	26 ft
6 AWG	282 ft	169 ft	84 ft	56 ft	42 ft
4 AWG	449 ft	269 ft	134 ft	89 ft	67 ft
3 AWG	565 ft	339 ft	169 ft	113 ft	84 ft
2 AWG	713 ft	428 ft	214 ft	142 ft	107 ft
1 AWG	899 ft	539 ft	269 ft	179 ft	134 ft
1/0 AWG	1135 ft	681 ft	340 ft	227 ft	170 ft
2/0 AWG	1432 ft	859 ft	429 ft	286 ft	214 ft
3/0 AWG	1808 ft	1084 ft	542 ft	361 ft	271 ft
4/0 AWG	2277 ft	1366 ft	683 ft	455 ft	341 ft
250 kcmil	2689 ft	1613 ft	806 ft	537 ft	403 ft
300 kcmil	3228 ft	1937 ft	968 ft	645 ft	484 ft
350 kcmil	3773 ft	2264 ft	1132 ft	754 ft	566 ft
400 kcmil	4314 ft	2588 ft	1294 ft	862 ft	647 ft
500 kcmil	5368 ft	3220 ft	1610 ft	1073 ft	805 ft

14 AWG Voltage Drop at 277V

Voltage drop values for 14 AWG copper conductor (3.14 ohms/kft) at 277 volts, single phase. Ampacity at 75°C: 20A. Cells in red exceed the 3% NEC recommendation.

Distance	30A	50A	100A	150A	200A
25 ft	4.7V 1.7%	7.8V 2.8%	15.7V 5.7%	23.6V 8.5%	31.4V 11.3%
50 ft	9.4V 3.4%	15.7V 5.7%	31.4V 11.3%	47.1V 17.0%	62.8V 22.7%
75 ft	14.1V 5.1%	23.6V 8.5%	47.1V 17.0%	70.7V 25.5%	94.2V 34.0%
100 ft	18.8V 6.8%	31.4V 11.3%	62.8V 22.7%	94.2V 34.0%	125.6V 45.3%
125 ft	23.6V 8.5%	39.3V 14.2%	78.5V 28.3%	117.8V 42.5%	157.0V 56.7%
150 ft	28.3V 10.2%	47.1V 17.0%	94.2V 34.0%	141.3V 51.0%	188.4V 68.0%
200 ft	37.7V 13.6%	62.8V 22.7%	125.6V 45.3%	188.4V 68.0%	251.2V 90.7%
250 ft	47.1V 17.0%	78.5V 28.3%	157.0V 56.7%	235.5V 85.0%	314.0V 113.4%
300 ft	56.5V 20.4%	94.2V 34.0%	188.4V 68.0%	282.6V 102.0%	376.8V 136.0%
400 ft	75.4V 27.2%	125.6V 45.3%	251.2V 90.7%	376.8V 136.0%	502.4V 181.4%
500 ft	94.2V 34.0%	157.0V 56.7%	314.0V 113.4%	471.0V 170.0%	628.0V 226.7%

12 AWG Voltage Drop at 277V

Voltage drop values for 12 AWG copper conductor (1.98 ohms/kft) at 277 volts, single phase. Ampacity at 75°C: 25A. Cells in red exceed the 3% NEC recommendation.

Distance	30A	50A	100A	150A	200A
25 ft	3.0V 1.1%	5.0V 1.8%	9.9V 3.6%	14.8V 5.4%	19.8V 7.2%
50 ft	5.9V 2.1%	9.9V 3.6%	19.8V 7.2%	29.7V 10.7%	39.6V 14.3%
75 ft	8.9V 3.2%	14.8V 5.4%	29.7V 10.7%	44.5V 16.1%	59.4V 21.4%
100 ft	11.9V 4.3%	19.8V 7.2%	39.6V 14.3%	59.4V 21.4%	79.2V 28.6%
125 ft	14.8V 5.4%	24.8V 8.9%	49.5V 17.9%	74.3V 26.8%	99.0V 35.7%
150 ft	17.8V 6.4%	29.7V 10.7%	59.4V 21.4%	89.1V 32.2%	118.8V 42.9%
200 ft	23.8V 8.6%	39.6V 14.3%	79.2V 28.6%	118.8V 42.9%	158.4V 57.2%
250 ft	29.7V 10.7%	49.5V 17.9%	99.0V 35.7%	148.5V 53.6%	198.0V 71.5%
300 ft	35.6V 12.9%	59.4V 21.4%	118.8V 42.9%	178.2V 64.3%	237.6V 85.8%
400 ft	47.5V 17.2%	79.2V 28.6%	158.4V 57.2%	237.6V 85.8%	316.8V 114.4%
500 ft	59.4V 21.4%	99.0V 35.7%	198.0V 71.5%	297.0V 107.2%	396.0V 143.0%

10 AWG Voltage Drop at 277V

Voltage drop values for 10 AWG copper conductor (1.24 ohms/kft) at 277 volts, single phase. Ampacity at 75°C: 35A. Cells in red exceed the 3% NEC recommendation.

Distance	30A	50A	100A	150A	200A
25 ft	1.9V 0.7%	3.1V 1.1%	6.2V 2.2%	9.3V 3.4%	12.4V 4.5%
50 ft	3.7V 1.3%	6.2V 2.2%	12.4V 4.5%	18.6V 6.7%	24.8V 8.9%
75 ft	5.6V 2.0%	9.3V 3.4%	18.6V 6.7%	27.9V 10.1%	37.2V 13.4%
100 ft	7.4V 2.7%	12.4V 4.5%	24.8V 8.9%	37.2V 13.4%	49.6V 17.9%
125 ft	9.3V 3.4%	15.5V 5.6%	31.0V 11.2%	46.5V 16.8%	62.0V 22.4%
150 ft	11.2V 4.0%	18.6V 6.7%	37.2V 13.4%	55.8V 20.1%	74.4V 26.9%
200 ft	14.9V 5.4%	24.8V 8.9%	49.6V 17.9%	74.4V 26.9%	99.2V 35.8%
250 ft	18.6V 6.7%	31.0V 11.2%	62.0V 22.4%	93.0V 33.6%	124.0V 44.8%
300 ft	22.3V 8.1%	37.2V 13.4%	74.4V 26.9%	111.6V 40.3%	148.8V 53.7%
400 ft	29.8V 10.7%	49.6V 17.9%	99.2V 35.8%	148.8V 53.7%	198.4V 71.6%
500 ft	37.2V 13.4%	62.0V 22.4%	124.0V 44.8%	186.0V 67.2%	248.0V 89.5%

8 AWG Voltage Drop at 277V

Voltage drop values for 8 AWG copper conductor (0.778 ohms/kft) at 277 volts, single phase. Ampacity at 75°C: 50A. Cells in red exceed the 3% NEC recommendation.

Distance	30A	50A	100A	150A	200A
25 ft	1.2V 0.4%	1.9V 0.7%	3.9V 1.4%	5.8V 2.1%	7.8V 2.8%
50 ft	2.3V 0.8%	3.9V 1.4%	7.8V 2.8%	11.7V 4.2%	15.6V 5.6%
75 ft	3.5V 1.3%	5.8V 2.1%	11.7V 4.2%	17.5V 6.3%	23.3V 8.4%
100 ft	4.7V 1.7%	7.8V 2.8%	15.6V 5.6%	23.3V 8.4%	31.1V 11.2%
125 ft	5.8V 2.1%	9.7V 3.5%	19.4V 7.0%	29.2V 10.5%	38.9V 14.0%
150 ft	7.0V 2.5%	11.7V 4.2%	23.3V 8.4%	35.0V 12.6%	46.7V 16.9%
200 ft	9.3V 3.4%	15.6V 5.6%	31.1V 11.2%	46.7V 16.9%	62.2V 22.5%
250 ft	11.7V 4.2%	19.4V 7.0%	38.9V 14.0%	58.4V 21.1%	77.8V 28.1%
300 ft	14.0V 5.1%	23.3V 8.4%	46.7V 16.9%	70.0V 25.3%	93.4V 33.7%
400 ft	18.7V 6.7%	31.1V 11.2%	62.2V 22.5%	93.4V 33.7%	124.5V 44.9%
500 ft	23.3V 8.4%	38.9V 14.0%	77.8V 28.1%	116.7V 42.1%	155.6V 56.2%

6 AWG Voltage Drop at 277V

Voltage drop values for 6 AWG copper conductor (0.491 ohms/kft) at 277 volts, single phase. Ampacity at 75°C: 65A. Cells in red exceed the 3% NEC recommendation.

Distance	30A	50A	100A	150A	200A
25 ft	0.7V 0.3%	1.2V 0.4%	2.5V 0.9%	3.7V 1.3%	4.9V 1.8%
50 ft	1.5V 0.5%	2.5V 0.9%	4.9V 1.8%	7.4V 2.7%	9.8V 3.5%
75 ft	2.2V 0.8%	3.7V 1.3%	7.4V 2.7%	11.1V 4.0%	14.7V 5.3%
100 ft	3.0V 1.1%	4.9V 1.8%	9.8V 3.5%	14.7V 5.3%	19.6V 7.1%
125 ft	3.7V 1.3%	6.1V 2.2%	12.3V 4.4%	18.4V 6.7%	24.6V 8.9%
150 ft	4.4V 1.6%	7.4V 2.7%	14.7V 5.3%	22.1V 8.0%	29.5V 10.6%
200 ft	5.9V 2.1%	9.8V 3.5%	19.6V 7.1%	29.5V 10.6%	39.3V 14.2%
250 ft	7.4V 2.7%	12.3V 4.4%	24.6V 8.9%	36.8V 13.3%	49.1V 17.7%
300 ft	8.8V 3.2%	14.7V 5.3%	29.5V 10.6%	44.2V 15.9%	58.9V 21.3%
400 ft	11.8V 4.3%	19.6V 7.1%	39.3V 14.2%	58.9V 21.3%	78.6V 28.4%
500 ft	14.7V 5.3%	24.6V 8.9%	49.1V 17.7%	73.7V 26.6%	98.2V 35.5%

4 AWG Voltage Drop at 277V

Voltage drop values for 4 AWG copper conductor (0.308 ohms/kft) at 277 volts, single phase. Ampacity at 75°C: 85A. Cells in red exceed the 3% NEC recommendation.

Distance	30A	50A	100A	150A	200A
25 ft	0.5V 0.2%	0.8V 0.3%	1.5V 0.6%	2.3V 0.8%	3.1V 1.1%
50 ft	0.9V 0.3%	1.5V 0.6%	3.1V 1.1%	4.6V 1.7%	6.2V 2.2%
75 ft	1.4V 0.5%	2.3V 0.8%	4.6V 1.7%	6.9V 2.5%	9.2V 3.3%
100 ft	1.9V 0.7%	3.1V 1.1%	6.2V 2.2%	9.2V 3.3%	12.3V 4.5%
125 ft	2.3V 0.8%	3.9V 1.4%	7.7V 2.8%	11.6V 4.2%	15.4V 5.6%
150 ft	2.8V 1.0%	4.6V 1.7%	9.2V 3.3%	13.9V 5.0%	18.5V 6.7%
200 ft	3.7V 1.3%	6.2V 2.2%	12.3V 4.5%	18.5V 6.7%	24.6V 8.9%
250 ft	4.6V 1.7%	7.7V 2.8%	15.4V 5.6%	23.1V 8.3%	30.8V 11.1%
300 ft	5.5V 2.0%	9.2V 3.3%	18.5V 6.7%	27.7V 10.0%	37.0V 13.3%
400 ft	7.4V 2.7%	12.3V 4.5%	24.6V 8.9%	37.0V 13.3%	49.3V 17.8%
500 ft	9.2V 3.3%	15.4V 5.6%	30.8V 11.1%	46.2V 16.7%	61.6V 22.2%

3 AWG Voltage Drop at 277V

Voltage drop values for 3 AWG copper conductor (0.245 ohms/kft) at 277 volts, single phase. Ampacity at 75°C: 100A. Cells in red exceed the 3% NEC recommendation.

Distance	30A	50A	100A	150A	200A
25 ft	0.4V 0.1%	0.6V 0.2%	1.2V 0.4%	1.8V 0.7%	2.5V 0.9%
50 ft	0.7V 0.3%	1.2V 0.4%	2.5V 0.9%	3.7V 1.3%	4.9V 1.8%
75 ft	1.1V 0.4%	1.8V 0.7%	3.7V 1.3%	5.5V 2.0%	7.3V 2.6%
100 ft	1.5V 0.5%	2.5V 0.9%	4.9V 1.8%	7.3V 2.6%	9.8V 3.5%
125 ft	1.8V 0.7%	3.1V 1.1%	6.1V 2.2%	9.2V 3.3%	12.3V 4.4%
150 ft	2.2V 0.8%	3.7V 1.3%	7.3V 2.6%	11.0V 4.0%	14.7V 5.3%
200 ft	2.9V 1.1%	4.9V 1.8%	9.8V 3.5%	14.7V 5.3%	19.6V 7.1%
250 ft	3.7V 1.3%	6.1V 2.2%	12.3V 4.4%	18.4V 6.6%	24.5V 8.8%
300 ft	4.4V 1.6%	7.3V 2.6%	14.7V 5.3%	22.1V 8.0%	29.4V 10.6%
400 ft	5.9V 2.1%	9.8V 3.5%	19.6V 7.1%	29.4V 10.6%	39.2V 14.2%
500 ft	7.3V 2.6%	12.3V 4.4%	24.5V 8.8%	36.8V 13.3%	49.0V 17.7%

2 AWG Voltage Drop at 277V

Voltage drop values for 2 AWG copper conductor (0.194 ohms/kft) at 277 volts, single phase. Ampacity at 75°C: 115A. Cells in red exceed the 3% NEC recommendation.

Distance	30A	50A	100A	150A	200A
25 ft	0.3V 0.1%	0.5V 0.2%	1.0V 0.3%	1.5V 0.5%	1.9V 0.7%
50 ft	0.6V 0.2%	1.0V 0.3%	1.9V 0.7%	2.9V 1.1%	3.9V 1.4%
75 ft	0.9V 0.3%	1.5V 0.5%	2.9V 1.1%	4.4V 1.6%	5.8V 2.1%
100 ft	1.2V 0.4%	1.9V 0.7%	3.9V 1.4%	5.8V 2.1%	7.8V 2.8%
125 ft	1.5V 0.5%	2.4V 0.9%	4.8V 1.8%	7.3V 2.6%	9.7V 3.5%
150 ft	1.8V 0.6%	2.9V 1.1%	5.8V 2.1%	8.7V 3.1%	11.6V 4.2%
200 ft	2.3V 0.8%	3.9V 1.4%	7.8V 2.8%	11.6V 4.2%	15.5V 5.6%
250 ft	2.9V 1.1%	4.8V 1.8%	9.7V 3.5%	14.6V 5.3%	19.4V 7.0%
300 ft	3.5V 1.3%	5.8V 2.1%	11.6V 4.2%	17.5V 6.3%	23.3V 8.4%
400 ft	4.7V 1.7%	7.8V 2.8%	15.5V 5.6%	23.3V 8.4%	31.0V 11.2%
500 ft	5.8V 2.1%	9.7V 3.5%	19.4V 7.0%	29.1V 10.5%	38.8V 14.0%

1 AWG Voltage Drop at 277V

Voltage drop values for 1 AWG copper conductor (0.154 ohms/kft) at 277 volts, single phase. Ampacity at 75°C: 130A. Cells in red exceed the 3% NEC recommendation.

Distance	30A	50A	100A	150A	200A
25 ft	0.2V 0.1%	0.4V 0.1%	0.8V 0.3%	1.2V 0.4%	1.5V 0.6%
50 ft	0.5V 0.2%	0.8V 0.3%	1.5V 0.6%	2.3V 0.8%	3.1V 1.1%
75 ft	0.7V 0.3%	1.2V 0.4%	2.3V 0.8%	3.5V 1.3%	4.6V 1.7%
100 ft	0.9V 0.3%	1.5V 0.6%	3.1V 1.1%	4.6V 1.7%	6.2V 2.2%
125 ft	1.2V 0.4%	1.9V 0.7%	3.9V 1.4%	5.8V 2.1%	7.7V 2.8%
150 ft	1.4V 0.5%	2.3V 0.8%	4.6V 1.7%	6.9V 2.5%	9.2V 3.3%
200 ft	1.9V 0.7%	3.1V 1.1%	6.2V 2.2%	9.2V 3.3%	12.3V 4.5%
250 ft	2.3V 0.8%	3.9V 1.4%	7.7V 2.8%	11.6V 4.2%	15.4V 5.6%
300 ft	2.8V 1.0%	4.6V 1.7%	9.2V 3.3%	13.9V 5.0%	18.5V 6.7%
400 ft	3.7V 1.3%	6.2V 2.2%	12.3V 4.5%	18.5V 6.7%	24.6V 8.9%
500 ft	4.6V 1.7%	7.7V 2.8%	15.4V 5.6%	23.1V 8.3%	30.8V 11.1%

1/0 AWG Voltage Drop at 277V

Voltage drop values for 1/0 AWG copper conductor (0.122 ohms/kft) at 277 volts, single phase. Ampacity at 75°C: 150A. Cells in red exceed the 3% NEC recommendation.

Distance	30A	50A	100A	150A	200A
25 ft	0.2V 0.1%	0.3V 0.1%	0.6V 0.2%	0.9V 0.3%	1.2V 0.4%
50 ft	0.4V 0.1%	0.6V 0.2%	1.2V 0.4%	1.8V 0.7%	2.4V 0.9%
75 ft	0.6V 0.2%	0.9V 0.3%	1.8V 0.7%	2.8V 1.0%	3.7V 1.3%
100 ft	0.7V 0.3%	1.2V 0.4%	2.4V 0.9%	3.7V 1.3%	4.9V 1.8%
125 ft	0.9V 0.3%	1.5V 0.6%	3.0V 1.1%	4.6V 1.6%	6.1V 2.2%
150 ft	1.1V 0.4%	1.8V 0.7%	3.7V 1.3%	5.5V 2.0%	7.3V 2.6%
200 ft	1.5V 0.5%	2.4V 0.9%	4.9V 1.8%	7.3V 2.6%	9.8V 3.5%
250 ft	1.8V 0.7%	3.0V 1.1%	6.1V 2.2%	9.2V 3.3%	12.2V 4.4%
300 ft	2.2V 0.8%	3.7V 1.3%	7.3V 2.6%	11.0V 4.0%	14.6V 5.3%
400 ft	2.9V 1.1%	4.9V 1.8%	9.8V 3.5%	14.6V 5.3%	19.5V 7.0%
500 ft	3.7V 1.3%	6.1V 2.2%	12.2V 4.4%	18.3V 6.6%	24.4V 8.8%

Other Voltage Levels

View voltage drop tables for other standard voltages. Higher voltages result in lower percentage voltage drop for the same absolute voltage loss, which allows longer conductor runs without upsizing.

120 Volt

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