Finding break in ring main Ask questions and find answers to many subjects relating to electrics and electrical work

[martynfogg]

Hello,

I was attempting to extend my ring main to add a socket at the weekend. I removed the wires from a socket, tested them and found one live cable and two not live.

This suggests that the socket had two ring main cables going in and one spur, but one side of the ring main had a break in it. I couldn't tell which was the spur and which were the ring main cables, so I couldn't extend the ring main.

I've opened up all the sockets in the house and they all seem to be wired correctly, although I didn't remove and clean up all the wires.

How can I find out where the problem is? Are there any test tools available?

My house is an early 40's BISF steel frame construction.

Many thanks,


Martyn Fogg

[sparx]

Hi Martyn, there is test kit available, from plug in checker @ £15ish up to pro signal injector we use @£100+ but often logical approach beats all.
If you think about ring circuit it is as name says a loop going out from fuse around house and back, but if you draw it as a circle and break it say half way all sockets will still be live, fed from both ends. now if you have another break in one half all sockets between 2 breaks will be dead.
So as you have made one break any sockets not now working must be between breaks, mark any which are dead, this should cut down number to look at.
One thing occurs to me if house is 1940's presume it has been rewired with rings not radials as it would have had originally, ie are there 2 cables at fuse/mcb in board?
regards SPARX

[martynfogg]

Thank you Sparx, I'll run some tests asap. Could you point me to any signal injectors links - might be a good investment? PM me if you don't want to advertise on the forum.

[sparx]

Hi martyn PM disabled on here,
I use a martindale unit which is quite old and has been superceded by a later model 'Elite Pro fuse finder Kit' advertised @ around£80.00 in various catalogues ie ""qvsdirect" or from local electrical wholesalers, advertised as fuse finder as one main use is to locate which fuse/mcb supplies a particular outlet by plugging into socket or croc clipping to light, however it then lets you identify which other points are on same circuit, then by disconnecting as i said above if unit on outlet near con unit easy to find breaks etc, needs thinking about but many uses,
regards SPARX