RATING FACTORS FOR VARIATION IN
AMPIENT TEMPERATURE FOR CABLES LAID IN AIR
| Ambient temperature °C |
25 |
30 |
35 |
40 |
45 |
50 |
52 |
55 |
60 |
| XLPE insulated cables |
1.37 |
1.30 |
1.24 |
1.17 |
1.09 |
1.03 |
1.00 |
0.95 |
0.88 |
RATING FACTORS FOR VARIATION IN GROUND TEMPERATURE
FOR CABLES LAID DIRECT IN GROUND OR IN DUCTS
| Ground Temperature °C |
15 |
20 |
25 |
30 |
35 |
40 |
45 |
| XLPE insulated cables |
1.16 |
1.13 |
1.08 |
1.03 |
1.00 |
0.95 |
0.90 |
RATING FACTORS FOR DEPTHS OF LAYING FOR
CABLES LAID DIRECT IN GROUND OR IN DUCTS
|
Depth of Laying
Metre
|
600/1000 V Cables 1.9/3.3 KV to 19/33 KV Cables
|
| Cables Laid in Ground |
Cables Laid in Ducts |
Cables Laid in Ground |
| upto 50 Sqmm |
70 Sqmm to
300 Sqmm |
Above
300 Sqmm |
Multicore |
Upto
300 Sqmm |
Above
300 Sqmm |
| 0.50 |
1.026 |
1.036 |
1.055 |
1.026 |
- |
- |
| 0.60 |
1.015 |
1.016 |
1.023 |
1.015 |
- |
- |
| 0.75 |
1.000 |
1.000 |
1.000 |
1.000 |
- |
- |
| |
| 0.80 |
0.995 |
0.995 |
0.992 |
0.995 |
1.020 |
1.031 |
| 1.00 |
0.974 |
0.975 |
0.970 |
0.985 |
1.000 |
1.000 |
| 1.25 |
0.964 |
0.953 |
0.949 |
0.974 |
0.980 |
0.979 |
| |
| 1.50 |
0.954 |
0.943 |
0.939 |
0.964 |
0.969 |
0.969 |
| 1.75 |
0.944 |
0.922 |
0.918 |
0.964 |
0.959 |
0.948 |
| 2.00 |
0.933 |
0.912 |
0.907 |
0.954 |
0.939 |
0.928 |
| |
| 2.50 |
0.923 |
0.902 |
0.897 |
0.954 |
0.929 |
0.918 |
| 3.00 |
0.913 |
0.891 |
0.876 |
0.944 |
0.918 |
0.907 |
| or more |
|
|
|
|
|
|
Depth of laying is measured from surface of ground to the centre of a Cable/Duct or to the centre of a trefoil group of Cables/ducts as the case may be.