Table 9
Rating Factors The tabulated ratings must be reduced for ambient air temperatures higher than 30 0 C; appropriate temperature ratings factors are as follows: -
Ambient Temperature
25 0 C 30 0 C 35 0 C 40 0 C 45 0 C 50 0 C 55 0 C 60 0 C
PVC 70 0 C
1.03
1
0.94 0.87 0.79 0.71 0.61
0.5
Thermosetting 90 0 C (XLPE or LSF)
1.02
1
0.96 0.91 0.87 0.82 0.76 0.71
Table 10
Group Rating Factors Rating factors for one circuit or one multicore cable or for a group of circuits, or a group of multicore cables, to be used with current carrying capacities of Table 6 & 7
Arrangement (cables touching)
Number of circuits or multicore cables
To be used with current carrying capacities, Reference
1 2 3 4 5 6 7 8 9 12 16 20
Bunched in air, on a surface, embedded or enclosed Single layer on wall or floor
1.00 0.80 0.70 0.65 0.60 0.57 0.54 0.52 0.50 0.45 0.41 0.38 Methods A to F
1.00 0.85 0.79 0.75 0.73 0.72 0.72 0.71 0.70 0.70 0.70 0.70 Method C
NOTE 1: These factors are applicable to uniform groups of cables, equally loaded.
NOTE 2: Where horizontal clearances between adjacent cables exceeds twice their overall diameter, no rating factor need be applied. NOTE 3: If a group consists of n single-core cables it may either be considered as n /2 circuits of two loaded conductors or n /3 circuits of three loaded conductors.
15 MKXXS001-04/01-08-2015
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