Ampacities and Mechanical Properties of Rectangular Copper Busbars

Quick Busbar 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 Table 1.

Required Ampacity,* (Range) Amp Busbar Dimensions, In.**
30 °C Rise 50 °C Rise 65 °C Rise
100
(100-149)		 1/16x1/2,1/16x3/4 1/16x1/2
150
(150-199)		 1/16x1
1/8x1/2
3/16x1/2		 1/16x3/4 1/16x1/2
200
(200-249)		 1/8x3/4
1/4x1/2		 1/8x1/2 1/16x3/4
1/8x1/2

250
(250-299)

 1/16x1 1/2
1/8x1
3/16x3/4		 1/16x1
1/8x3/4
3/16x1/2		 1/16x1

300
(300-349)

 1/16x2
3/16x1
1/4x3/4		 1/4x1/2 1/8x3/4
3/16x1/2
350
(350-399)		 1/8x1 1/2 1/16x1 1/2
1/8x1
3/16x3/4		 1/4x1/2
400
(400-449)		 1/4x3/4
3/8x3/4		 1/4x3/4 1/4x1/2
400
(400-449)		 1/4x1
3/8x3/4		 1/4x3/4 1/16x1 1/2
1/8x1
3/16x3/4
450
(450-499)		 1/8x2
3/16x1/2		 1/16x2
3/16x1		 1/4x3/4
500
(500-599)
 1/4x1 1/2
3/8x1		 1/8x1 1/2
1/4x1
3/8x3/4		 1/16x2
1/8x1 1/2
3/16x1
600
(600-699)		 1/8x2 1/2
3/16x2
1/2x1
1/2x1		 1/8x2
3/16x1 1/2
1/4x1		 1/4x1
3/8x3/4
700
(700-799)		 1/8x3
3/16x2 1/2
1/4x2
3/8x1 1/2		 1/4x1 1/2 1/8x2
3/16x1 1/2
3/8x1
800
(800-899)		 1/8x3 1/2
3/16x3
1/4x2 1/2
3/8x2		 1/8x2 1/2
3/16x2
1/2x1		 1/4x1 1/2
900
(900-999)		 1/8x4
3/16x3 1/2
1/4x3		 1/8x3
3/16x2 1/2
1/4x2
3/8x1 1/2		 1/8x2 1/2
1/2x1
1000
(1000-1249)		 3/16x4 1/4x3 1/2
3/8x2 1/2, 3/8x3
1/2x2, 1/2x2 1/2		 1/8x4
3/16x3
1/4x2 1/2
3/8x2		 1/8x3
3/16x2 1/2
1/4x2
3/8x1 1/2
1250
(1250-1499)		 1/4x4
3/8x3 1/2
1/2x3		 3/16x3 1/2, 3/16x4
1/4x3
3/8x2 1/2
1/2x2		 1/8x4
3/16x3
1/4x2 1/2
3/8x2
1500
(1500-1749)		 1/4x5
3/8x4
1/2x3 1/2, 1/2x4		 1/4x3 1/2, 1/4x4
3/8x3
1/2x2 1/2		 3/16x3 1/2, 3/16x4
1/4x3
3/8x2 1/2
1/2x2
1750
(1750-1999)		 1/4x6
3/8x5		 3/8x3 1/2
1/2x3		 1/4x3 1/2, 1/4x4
3/8x3
1/2x2 1/2
2000
(2000-2499)		 1/4x8
3/8x6
1/2x5, 1/2x6
3/4x4, 3/4x5		 1/4x6
3/8x5
1/2x4		 1/4x5
3/8x4
1/2x3 1/2
2500
(2500-2999)		 1/4x10
3/8x8
3/4x6		 3/8x6
1/2x5
3/4x4		 1/4x6
3/8x5
1/2x4
3000
(3000-3499)		 1/4x12
3/8x10
1/2x8		 1/4x8
1/2x6
3/4x5		 1/4x8
3/8x6
1/2x5
3/4x4
3500
(3500-3999)		 3/8x12
1/2x10
3/4x8		 1/4x10
3/8x8
3/4x6		 1/2x6
3/4x5
4000
(4000-4499)		 1/2x12
3/4x10		 1/4x12
3/8x10
1/2x8		 1/4x10
3/8x8
3/4x6
4500
(4500-4999)		 3/4x12 1/2x10 3/4x8 1/4x12
3/8x10
1/2x8
5000
(5000-5999)		 3/8x12
1/2x12
3/4x10		 3/8x12
1/2x10
3/4x8
* For 60 Hz current

** Table gives bus bar cross sections which will probably be large enough for ampacities within each range. Knowing required ampacity, determine possible bus bar dimensions from the table. Then check Table 1 to verify that size selected has the necessary ampacity.

Example: Assume that required ampacity is 185 amp at 30 °C rise. Table 3 indicates that 1/16 x 1 in. size would probably be adequate. This is confirmed by Table 1 which lists the ampacity of 1/16 x 1 in. bus bar as 187 amp.