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Quick Copper Busbar Design Selector

Knowing the ampacity, designers and estimators can get the approximate bus bar size. Ampacity of the bus bar selected must then be verified by checking the Ampacity Table.

Required Ampacity  range*

Busbar Dimension, Inches**

 

30 °C Rise

50 °C Rise

65 °C Rise

100-149

1/16 x 1/2
1/16 x 3/4

1/16 x 1/2

 

150-199

1/16 x 1
1/8 x 1/2
3/16 x 1/2

1/16 x 3/4

1/16 x 1/2

200-249

1/8 x 3/4
1/4 x 1/2

1/8 x 1/2

1/16 x 3/4
1/8 x 1/2

250-299

1/16 x 1 1/2
1/8 x 1
3/16 x 3/4

1/16 x 1
1/8 x 3/4
3/16 x 1/2

1/16 x 1

300-349

1/16 x 2
3/16 x 1
1/4 x 3/4

1/4 x 1/2

1/8 x 3/4
3/16 x 1/2

350-399

1/8 x 1 1/2

1/8 x 1
3/16 x 3/4

1/4 x 1/2

400-449

1/4 x 1
3/8 x 3/4

1/4 x 3/4

1/16 x 1 1/2
1/8 x 1
3/16 x 3/4

450-499

1/8 x 2
3/16 x 1 1/2

1/16 x 2
3/16 x 1

1/4 x 3/4

500-599

1/4 x 1 1/2
3/8 x 1

1/8 x 1 1/2
1/4 x 1
3/8 x 3/4

1/16 x 2
1/8 x 1 1/2
3/16 x 1

600-699

1/8 x 2 1/2
3/16 x 2
1/2 x 1

1/8 x 2
3/16 x 1 1/2
3/8 x 1

1/4 x 1
3/8 x 3/4

700-799

1/8 x 3
3/16 x 2 1/2
1/4 x 2
3/8 1 1/2

1/4 x 1 1/2

1/8 x 2
3/16 x 1 1/2
3/8 x 1

800-899

1/8 x 3 1/2
3/16 x 3
1/4 x 2 1/2
3/8 x 2

1/8 x 2 1/2
3/16 x 2
1/2 x 1

1/4 x 1 1/2

900-999

3/16 x 3 1/2
1/4 x 3

3/16 x 2 1/2
1/4 x 2
3/8 x 1 1/2

3/16 x 2
1/2 x1

1000-1249

3/16 x 4
1/4 x 3 1/2
3/8 x 2 1/2
3/8 x 3
1/2 x 2
1/2 x 2 1/2

1/8 x 4
3/16 x 3
1/4 x 2 1/2
3/8 x 2

1/8 x 3
3/16 x 2 1/2
1/4 x 2
3/8 x 1 1/2

1250-1499

1/4 x 4
3/8 x 3 1/2
1/2 x 3

3/16 x 3 1/2
3/16 x 4
1/4 x 3
3/8 x 2 1/2
1/2 x 2

1/8 x 4
3/16 x 3
1/4 2 1/2
3/8 x 2

1500-1749

1/4 x 5
3/8 x 4
1/2 x 3 1/2
1/2 x 4

1/4 x 3 1/2
1/4 x 4
3/8 x 3
1/2 x 2 1/2

3/16 x 3 1/2
3/16 x 4
1/4 x 3
3/8 x 2 1/2
1/2 x 2

1750-1999

1/4 x 6
3/8 x 5

3/8 x 3 1/2
1/2 x 3

1/4 x 3 1/2
1/4 x 4
3/8 x 3
1/2 x 2 1/2

2000-2499

1/4 x 8
3/8 x 6
1/2 x 5
1/2 x 6

1/4 x 6
3/8 x 5
1/2 x 4

1/4 x 5
3/8 x 4
1/2 x 3 1/2

2500-2999

1/4 x 10
3/8 x 8

3/8 x 6
1/2 x 5

1/4 x 6
3/8 x 5
1/2 x 4

* For 60 Hz current.

** Table gives busbar cross section which will probably be large enough for Ampacities within each range. Knowing required ampacity, determine possible busbar dimensions from this table. Then check the Ampacity Table to verify that size selected has the necessary ampacity.

Example: Assume that required ampacity is 185 amps at 30 °C rise. This table indicates that 1/16 x 1 in. size would probably be adequate. This is confirmed by the Ampacity Table which lists the ampacity of 1/6 x 1 in. busbar as 187 amps.

Table courtesy of Copper Development Association Inc. (www.copper.org)