print this page Email this page Add to del.icio.us bookmarks

Electrical

Loading

DC Copper Busbar Ampacities

The following tables have been provided by the Alliance for Telecommunications Industry Solutions (ATIS), T1 Committee, and represent ampacities for busbar sizes and arrangements typically found in the telecommunications industry. The number of sizes shown are not as extensive as those in the tables of AC ampacities, and there may be slight discrepancies between the ampacities shown here and those obtained by calculations derived from AC ampacities. CDA would encourage the reader to use the more conservative of the two figures, if there is a discrepancy.

The ampacities that follow are from Table 5 of Standard T1.311, and are reproduced here solely for the convenience of the viewer. Further reproduction or use of this document is prohibited without the express written permission of ATIS.

If you wish to purchase a copy of the complete Standard, please visit the ATIS Document Center.

No. of Bars Thickness Width Cross-section Area(cm) Ampacity Copper
A1 B2
1 1/8 ½
¾
1
1½
2		 79.6
119.4
159.2
238.7
318.3		 154
215
275
390
503		 152
212
271
385
496
1 1/4 ½
1
1½
2
2½
3
3½
4
6
8		 159.2
318.3
477.5
636.6
795.8
954.9
1,114.0
1,273.0
1,910.0
2,546.0		 238
409
572
731
887
1,040
1,192
1,342
1,931
3,092		 234
403
564
721
869
1,019
1,152
1,295
1,820
2,828
1 3/8 1
1½
2
2½
3
4
6
8		 477.5
716.2
954.9
1,194.0
1,432.0
1,910.0
2,865.0
3,820.0		 524
724
919
1,110
1,298
1,667
2,388
3,092		 517
714
906
1,087
1,272
1,612
2,250
2,828
1 1/2 1
1½
2
3
4
6
8		 636.6
954.9
1,273.0
1,910.0
2,546.0
3,820.0
5,093.0 		632
863
1,088
1,523
1,951
2,783
3,596
 622
851
1,073
1,494
1,887
2,623
3,289
2 1/4 2
3
4
6
8		 1,273.0
1,910.0
2,546.0
3,820.0
5,093.0		 1,301
1,834
2,350
3,352
4,325		 1,259
1,735
2,163
2,937
3,583
2 1/2 2
3
4
6
8		 2,546.0
3,820.0
5,093.0
7,638.0
10,186.0		 1,961
2,715
3,445
4,861
6,236		 1,902
2,577
3,182
4,275
5,189
3 1/4 4
6
8		 3,820.0
5,730.0
7,640.0		 3,342
4,745
6,105		 2,996
3,992
4,770
3 1/2 4
6
8		 7,639.0
11,459.0
15,278.0		 4,918
6,902
8,824		 4,437
5,848
6,950
4 1/4 2
3
4
6
8		 2,546.0
3,820.0
5,093.0
7,639.0
10,186.0		 2,426
3,394
4,328
6,130
7,872		 2,313
3,123
3,819
5,026
5,916
4 1/2 4
6
8		 10,168.0
15,278.0
20,371.0		 6,384
8,933
11,395		 5,673
7,392
8,659
5 1/4 4
6
8		 6,365.0
9,550.0
12,710.0		 5,312
7,512
9,634		 4,637
6,048
7,041
5 1/2 4
6
8		 12,732.0
19,098.0
25,464.0		 7,847
10,960
13,960		 6,915
8,921
10,340
6 1/4 4
6
8		 7,610.0
11,410.0
15,330.0		 6,295
8,891
11,395		 5,452
7,064
8,154
6 1/2 4
6
8		 15,278.0
22,918.0
30,557.0		 9,309
12,980
16,520		 8,148
10,445
12,005
7 1/4 6
8		 13,370.0
17,822.0		 10,270
13,150		 8,076
9,259
7 1/2 6
8		 26,737.0
35,650.0		 15,000
19,080		 11,960
13,660
8 1/4 6
8		 15,280.0
20,372.0		 11,645
14,905		 9,086
10,360
8 1/2 6
8		 30,557.0
40,742.0		 17,020
21,635		 13,475
15,310
9 1/4 6
8		 17,190.0
22,914.0		 13,020
16,660		 10,095
11,455
9 1/2 6
8		 34,376.0
45,835.0		 19,040
24,190		 14,985
16,955
10 1/4 6
8		 19,100.0
25,460.0		 14,400
18,415		 11,100
12,545
10 1/2 6
8		 38,190.0
50,928.0		 21,060
26,745		 16,495
18,600
11 1/4 6
8		 21,010.0
28,013.0		 15,775
20,170		 12,105
13,640
12 1/4 6
8		 22,920.0
30,560.0		 17,150
21,925		 13,110
14,725

1. The ampacity rating is based on a 30C rise above a 40C ambient. The bars are run with their long axis vertical. The spacing between bars is equal to or more than their thickness, and the bars are run in a horizontal plane.

2. Ampacity rating to be used when the long axis of the bars is in the horizontal plane, or when the spacing between bars is less than the thickness of the bars, or when the bars are run in a vertical direction.

3. The minimum bending radius for copper is equal to the thickness of the bar. The minimum bending radius for aluminum is equal to twice the thickness of the bar. The surface roughening that may occur at the bend is not serious as long as it is only a surface condition.

4. The copper bus bar is ETP-110 100% IACS (International Annealed Copper Standard) conductivity (0.15328 ohm-gram/square meter) per ASTM B187. The resistivity is 10.371 ohm circular mils/foot at 20C surface of the cable. The minimum bend radii may be reduced only if specifically allowed by the conductor manufacturer.

Learn More

Order educational, and technical publications and video.