Hi Badger,
If I follow your logic, you are saying that in the event of the continuity of the cpc being broken, with no damage or shorting to live or neutral, which would trigger circuit protection, then all outlets would function as normal. That means the fault could exist, but could stay undiscovered. In the meantime, the Zs of the outlets would increase substantially, due to radial cpc only, which could jeopardise disconnection times. Also, you would effectively have a 5mm cable ( 2 x 2.5mm), backed up by only a 1.5mm cpc, which probably doesn't meet the criteria for reduced cpc size allowances.
When you say it is a better wiring system, I assume you mean better than radials. Let's take a 32A kitchen ring circuit versus 2 x 20A radials. Ring capacity, 32A, total radial capacity, 40A. If a fault develops on the ring, the whole ring is off. If a fault develops on a radial, maybe half the kitchen would still be working. It could be argued that less cable is used with the two radials, because you don't have to complete the ring. This could offset the cost of the extra MCB / RCBO. With a 20A radial, there is no such thing as a spur off a spur, which means later extensions would be easy and still be safe. Testing of 2 radials is easier than testing a ring circuit, etc .
Whilst I acknowledge there are good features of ring circuits, I cannot agree that it is a better wiring system. However, on your jobs, it is your opinion that counts, not mine.
Hi Pete 10001,
I too am a pensioner and a member of the IET. My memory is not as good as it once was, neither are my knees, but I still keep in touch with the Industry, via my SBS Trade Sales. I couldn't compete with these young guys, anyway, so I am happy for them to do all the installs, as long as they use my kit!!!
David Stansfield MIET
