Short Circuit Rating
When cables are subjected to temperatures higher than those permissible for continuous operation, they may suffer damage. Therefore, in installation, where there is a possibility of the cables being overloaded by mistake or accident, cables should be selected having regard to characteristics of the device used or protection against excess current, so that the effects of overloading are limited to a degree tolerable or a relatively short period of operation.
a) PVC Insulated Cables:
The values of fault current given in the tables below are based on the cable being fully loaded at the start of the short circuit (conductor temperature 70°C) and at final temperature of 160°C for conductors up to 300 mm 2
PVC INSULATED CABLES COPPER CONDUCTOR |
PVC INSULATED ALUMINUM CONDUCTOR |
Short Ciruit Current (in kilo amp.) |
Short Ciruit Current (in kilo amp.) |
Conductor Area |
Duration of Short-circuit Sec. |
Conductor Area |
Duration of Short-circuit Sec. |
0.2 |
0.5 |
1.0 |
2.0 |
3.0 |
0.2 |
0.5 |
1.0 |
2.0 |
3.0 |
10 mm 2 |
2.6 |
1.6 |
1.2 |
0.8 |
0.7 |
10 mm 2 |
1.7 |
1.0 |
0.7 |
0.6 |
0.5 |
16 mm 2 |
4.1 |
2.6 |
1.8 |
1.3 |
1.1 |
16 mm 2 |
2.6 |
1.7 |
1.2 |
0.93 |
0.8 |
25 mm 2 |
6.4 |
4.1 |
2.9 |
2.0 |
1.7 |
25 mm 2 |
4.1 |
2.7 |
1.9 |
1.4 |
1.2 |
35 mm 2 |
9.0 |
5.7 |
4.0 |
2.8 |
2.3 |
35 mm 2 |
5.9 |
3.5 |
2.5 |
1.8 |
1.5 |
50 mm 2 |
12.0 |
8.1 |
5.8 |
4.1 |
3.3 |
50 mm 2 |
8.2 |
5.2 |
3.8 |
2.6 |
2.1 |
70 mm 2 |
18.0 |
11.4 |
8.1 |
5.7 |
4.6 |
70 mm 2 |
11.0 |
.5 |
5.3 |
3.8 |
3.0 |
95 mm 2 |
24.4 |
15.5 |
10.9 |
7.7 |
6.3 |
95 mm 2 |
15.0 |
10 |
7.0 |
5.0 |
4.0 |
120 mm 2 |
30.9 |
19.5 |
13.8 |
9.8 |
8 |
120 mm 2 |
20.0 |
11 |
9.0 |
6.1 |
5.0 |
150 mm 2 |
38.6 |
24.4 |
17.3 |
12.2 |
10.0 |
150 mm 2 |
23.0 |
15.5 |
11.0 |
7.8 |
6.1 |
PVC INSULATED CABLES
COPPER CONDUCTORS
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