Ring main fault

[eagleeye]

I was called to a friends flat today after he had heard a big bang from the ring main. He said he checked the CU and the MCB was tripped, so not knowing anything about electrics he put it back on, he said it stayed on for a couple of seconds then tripped again. I went round to have a look and carried out a meg test on the circuit. L - E fine, N - E fine but the L - N is showing a dead short. Reading was 0.00. I checked that i had unpluged everything and i had. Circuit is run in singles and in metal conduit in concrete floors and walls. Im going back tomorrow to investergate further but has anyone got any ideas what it could be ?

 

[pushrod]

Don't know, but should be able to locate it by the method of halving and testing.

 

[keniff]

ah its a bugger when its in conduit like that! my approach would be take one leg of the ring out of the consumer unit then start at each accessory, disconnect each accessory and IR test each link one by one untill you get a clear reading, i had this once, turned out a spur out the back of socket was supplying an outside light filled with water other than a dodgy spur or hidden appliance still plugged in? good luck anyway!

 

[Hawk81]

spur off the ring somewhere? eg.. heating outside light, immersion etc

 

[Sparky Ninja]

Don't know, but should be able to locate it by the method of halving and testing.

whot he says.