Code of Practice for the Electricity (Wiring) Regulations - 2009 Edition

(2) Correction factors for groups of cables
Table A5(3)
Correction factors for groups of more than one circuit of
single-core cables, or more than one multicore cable
* ‘Spaced’ means a clearance between adjacent surfaces of at least one cable diameter (De).
Where the horizontal clearances between adjacent cables exceeds 2De, no correction factor
needs to be applied.
# Not applicable to Mineral Insulated Cables. Please refer to BS 7671 for the required correction
factors.
Notes to Table A5(3)
1. The factors in the table are applicable to groups of cables of one size
only. The value of current derived from application of the appropriate
factors is the maximum continuous current to be carried by any of the
cables in the group.
2. If, due to known operating conditions, a cable is expected to carry not
more than 30% of its grouped rating, it may be ignored for the purpose
of obtaining the rating factor for the rest of the group.
3. When cables having different conductor operating temperatures are
grouped together, the current rating should be based upon the lowest
operating temperature of any cable in the group.
253