ring Main query

[AnonymousImport]

Can any one explain to me about resistance on a ring main.
my mate who is an apprentice electrician recently added some sockets for me, he tested the circit with a continuity tester ans when the Neutral and earth had continuity the reading on his meter was zero, when he tested live although the meter buzzed to suggest continuity the reading was one. He said that this was acceptable. I am probably worrying over nothing but can not see why live should read different from neutral when power is off.
Anyway I hope one of you can put my mind at rest..

Thanks

Graeme

 

[AnonymousImport]

A ring main is essentially a loop, or really 3 loops of wire, one a live loop, one a neutral loop, and one an earth loop. Each of these loops originate at, and return to the consumer unit. The live loop terminates (both ends) at it's fused live feed, the neutral terminates at a common neutral strip, and the earth terminates at a common earth strip. At some point, usually where the main incoming supply terminates, the neutral is connected to the earth. This is what forms the PME (protection main earth) system. Because the continuity test on the live loop is carried out with the fuse removed, then the resistance reading is only that of the live loop. When the earth and neutral loops are tested, they are in effect in parallel with each other, and so present only half of the resistance of the live loop. I hope this answers your worry.