The current rating mentioned in above tables based on ambient temperature 30°C in accordance with IET Wiring regulations for Electrical Installations, BS 7671.
Rating Factor for variation in Ambient Air Temperature.
| Air Temperature (°C) |
25 |
30 |
35 |
40 |
45 |
50 |
55 |
60 |
| Rating Factor |
1.02 |
1.00 |
0.96 |
0.91 |
0.87 |
0.82 |
0.76 |
0.71 |
Rating Factor for one circuit or one multicore cable or for group of circuits or a group of multicore cables.
|
Arrangement
(cable Touching)
|
Number of Circuits or Multicore Cables |
| 1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
12 |
16 |
20 |
|
Bunched in Air, on a surface, embedded or enclosed
|
1.00 |
0.80 |
0.70 |
0.65 |
0.60 |
0.57 |
0.54 |
0.52 |
0.50 |
0.45 |
0.41 |
0.38 |
|
Single layer on wall or floor
|
1.00 |
0.85 |
0.79 |
0.75 |
0.73 |
0.72 |
0.72 |
0.71 |
0.70 |
0.70 |
0.70 |
0.70 |
|
Single layer multicore on a perforated horizontal or vertical cable tray system
|
1.00 |
0.88 |
0.82 |
0.77 |
0..75 |
0.73 |
0.73 |
0.72 |
0.72 |
0.72 |
0.72 |
0.72 |
|
Single layer multicore on cable ladder system or cleats etc.
|
1.00 |
0.87 |
0.82 |
0.80 |
0.80 |
0.79 |
0.79 |
0.78 |
0.78 |
0.78 |
0.78 |
0.78
|
Minimum Bending Radius
Single Core Multi Core Cable
Armoured -8 x OD Armoured -8 x ODUn Armoured - 6 x OD Un Armoured - 8 x ODWhere ‘OD’ is overall diameter of cable Where ‘OD’ is overall diameter of cable