Richie Webster asks about certification circuit schedules and how to input CPC information. His question has been answered by SELECT (Theme – Electrical Testing, Tools and Equipment):
Question:When filling out the circuit schedules on certification, I am unclear as to which figures should be used when using the armour or sheath of a cable as the circuit protective conductor (CPC).
My understanding is that these figures should be the k values in the various tables within Guidance Note 1. However, it has been brought to my attention by a former colleague, that it should be the equivalent copper size which should be input in this box. Is this so?
Nevertheless, whichever way is correct, would it be acceptable to input the CPC size as sheath, armour etc., instead of the size stated in these tables, as long as the inspector confirms that the size of the CPC complies with BS7671, either by these tables, or by the adiabatic equation?
If so, this would save a lot of time.
Answer: I suggest that the equivalent copper size would be most appropriate. I believe that some certification software packages will input a figure for the particular cable chosen.
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