Interconnected ring circuits

[Aok1]

I went to replace a few sockets for a customer, no big deal so i knocked the upstairs mcb off and stuck my tester in the socket and i was still live.

Back down to the CU and thought that the cables would probably be crossed between up and downstairs circuits, it turned out they were not crossed and only 1 cable feeds the upstairs and the other 3 are all connected to the ground floor ring.

Both MCBs have to off to kill power to the rings and i have continuity between 3 lives.

There has been 2 additional high level sockets installed in the 1st floor back bedroom which are live when the downstairs ring is on fed by 1 x 2.5mm to each socket.

I have had most of the sockets off to check them but i cannot see anything obvious and no spurs connected ,i suspect that the fault maybe in the kitchen as there are sockets installed in the floor under the units and kitchen is directly underneath that back bedroom with the 2 x high level spurs.

Also there are 2 x 2.5mm cable running up the kitchen wall which i suspect are the upstirs ring, i only know this as virgin media drilled through them, this is not the fault location as they had done this the day after i was there.

I was considering splitting the ring up to try and establish what goes were, also if i carrout R1 & R2 etc would this provide a rough idea to the location of the interconnection?

I have not come accross a interconnected ring before so any advice is appreciated.

Thanks

 

[trev]

If you were carrying out (R1+R2) what are you going to do with the third L&CPC? I'm not convinced that it would show where your 3rd cable joins mate. Top of my head I'm thinking you would have to split the circuit to find what's what. It's an odd problem.
Obviously, once you find where the 3rd cable joins you can decide on the best course of action to recommend to your client

 

[StuSpiers]

Yhea drop all fronts off, bell out.

Ball ache but will solve problem.

 

[telectrix]

pretty much the same. split at various sockets till found. allow several hours (including thinking time with a smoke)

 

[kingeri]

Trial and error - you might get lucky and find it straight away! Get stuck in!

 

[Aok1]

Thanks for the replies, went back today and took every socket off.

Half of the kitchen sockets wired from upstairs, dishwasher and cooker off another feed, so it's laminate and floorboards up tomorrow.