American, British, and Metric Standard Wire Gauge       

Sizes, Resistance, Voltage Drop, and Uses       

 

 

 

 

 

 

 

 

 

 

 

 

 

Standard

WG

 Approx. O.D.

Square

Resistance

Voltage Drop at 5 Amps

Used For

 

 

Inches

MM

Inches

MM

Ohms/Ft

Ohms/Meter

Volts/Ft

Volts/Meter

 

 

 

British

12

0.1040

2.64

0.0085

5.48

0.001

0.003

0.0050

0.0164

Power Bus Lengths over 100ft

American

10

0.1019

2.59

0.0082

5.26

0.001

0.003

0.0052

0.0171

Metric

25

0.0984

2.50

0.0076

4.90

0.001

0.004

0.0056

0.0183

British

13

0.0920

2.34

0.0066

4.29

0.001

0.004

0.0064

0.0210

American

12

0.0808

2.05

0.0051

3.31

0.002

0.005

0.0082

0.0272

Power Bus Lengths 50ft-100ft

British

14

0.0800

2.03

0.0050

3.24

0.002

0.006

0.0084

0.0277

Metric

20

0.0787

2.00

0.0049

3.14

0.002

0.006

0.0087

0.0287

British

15

0.0720

1.83

0.0041

2.63

0.002

0.007

0.0104

0.0342

Power Bus Lengths 30ft-50ft

Metric

18

0.0709

1.80

0.0039

2.55

0.002

0.007

0.0107

0.0353

American

14

0.0641

1.63

0.0032

2.08

0.003

0.009

0.0131

0.0432

British

16

0.0640

1.63

0.0032

2.07

0.003

0.009

0.0131

0.0433

Metric

16

0.0630

1.60

0.0031

2.01

0.003

0.009

0.0136

0.0447

Power Bus Lengths 00ft-30ft

British

17

0.0560

1.42

0.0025

1.59

0.003

0.011

0.0172

0.0566

Metric

14

0.0551

1.40

0.0024

1.54

0.004

0.012

0.0177

0.0585

American

16

0.0508

1.29

0.0020

1.31

0.004

0.014

0.0208

0.0688

British

18

0.0480

1.22

0.0018

1.17

0.005

0.015

0.0233

0.0770

Short splices to Power Bus.

Metric

12

0.0472

1.20

0.0017

1.13

0.005

0.016

0.0241

0.0797

American

18

0.0403

1.02

0.0013

0.82

0.007

0.022

0.0331

0.1093

British

19

0.0400

1.02

0.0013

0.81

0.007

0.022

0.0336

0.1110

Metric

10

0.0394

1.00

0.0012

0.79

0.007

0.023

0.0347

0.1144

British

20

0.0360

0.91

0.0010

0.66

0.008

0.027

0.0415

0.1370

Short Splices and Feeders

Metric

9

0.0354

0.90

0.0010

0.63

0.009

0.028

0.0429

0.1417

American

20

0.0320

0.81

0.0008

0.52

0.011

0.035

0.0525

0.1734

British

21

0.0320

0.81

0.0008

0.52

0.011

0.035

0.0525

0.1734

Metric

8

0.0315

0.80

0.0008

0.50

0.011

0.036

0.0542

0.1789

British

22

0.0280

0.71

0.0006

0.40

0.014

0.045

0.0686

0.2264

Drop Feeders, Rail to Bus

Metric

7

0.0276

0.70

0.0006

0.39

0.014

0.047

0.0706

0.2330

American

22

0.0253