Good afternoon learned colleagues.
Following on from my previous post about the use of 'YY' type cables, our esteemed client has stated that BS7671 does not have grouping factors for multicore cables. Personally I beg to differ in that table 4C1 states that it is 'rating factors for....a group of circuits or a group of multicore cables....' What's the hive mind opinion on that statement?
In our case, we have 4 x multicore cables, each carrying 3 circuits each so a total of 12 circuits. Should we use the figures from the column headed '4' or headed '12'? 12 would give us the worst case, and in fact we are well inside even this figure by our calculations.
Also, the design current for these circuits is only 1.24A, so it is well under the figue of 0.3 x Cg x It at which point under Note 9 arguably all of these circuits could be ignored for grouping purposes anyway. Do you agree with the vaidity of that argument?
We can park the 'YY' element of the argument for this discussion as the question would equally well apply to the use of a multicore SWA or Harmonised type cable - would you just use the total number of circuits involved from Table 4C1 or is there another method that should be used?
Thanks in advance.
Jason.
