How to calculate wire size by Voltage dropping Factory Suppliers Manufacturers Quotes

How to calculate wire size by Voltage dropping

Voltage drop can be calculated by ohms law in which E = R I. Where

E = voltage drop (Volts)

R = electrical resistance (Ohms)

I = current (Amps)

Example:

Voltage drop in a 100 ft power line: 2 x 100 ft, electrical resistance 1.02 Ohm/ 1000 ft, current: 10 Amps

E = 2 (0.00102 Ohm/ft) (100 ft) (10 Amps) = 2.04 Volts

 

Max wire feet @ 120 volts, 1 phase, 2% max voltage drop

 

Amps

Volt-Amps

#14

#12

#10

#8

#6

#4

#2

1/0

2/0

3/0

1

120

450

700

1100

1800

2800

4500

7000

-

-

-

5

600

90

140

225

360

575

910

1400

2250

2800

-

10

1200

45

70

115

180

285

455

705

1100

1400

1800

15

1800

30

47

75

120

190

305

485

770

965

1200

20

2400

-

36

57

90

140

230

365

575

725

900

25

3000

-

-

45

72

115

180

290

460

580

720

30

3600

-

-

38

60

95

150

240

385

490

600

40

4800

-

-

-

45

72

115

175

290

360

440

50

6000

-

-

-

-

57

90

145

230

290

360

60

7200

-

-

-

-

-

76

120

190

240

305

70

8400

-

-

-

-

-

65

105

165

205

260

80

9600

-

-

-

-

-

-

90

144

180

230

 

Max wire feet @ 240 volts, 1 phase, 2% max voltage drop

 

Amps

Volt-Amps

#14

#12

#10

#8

#6

#4

#2

1/0

2/0

3/0

1

240

900

1400

2200

3600

5600

9000

-

-

-

-

5

1200

180

285

455

720

1020

1750

2800

4500

5600

7000

10

2400

90

140

225

360

525

910

1400

2200

2800

3600

15

3600

60

95

150

240

350

605

965

1500

1900

2400

20

4800

-

70

110

180

265

455

725

1100

1400

1800

25

6000

-

-

90

144

210

365

580

920

1100

1440

30

7200

-

-

75

120

175

300

485

770

970

1200

40

5600

-

-

-

90

130

230

360

575

725

880

50

12000

-

-

-

-

105

180

290

460

580

720

60

14400

-

-

-

-

-

150

240

385

485

600

70

16800

-

-

-

-

-

130

205

330

415

520

80

19200

-

-

-

-

-

-

180

290

365

440

100

24000

-

-

-

-

-

-

-

230

280

360

150

36000

-

-

-

-

-

-

-

185

190

240

200

48000

-

-

-

-

-

-

-

-

-

180


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