3 cables make a loop?

[andekoch]

Just been asked to have a look at repairing an action that was on a PIR. It appears that there are 3 wires (from the socket 'ring') going in to the mcb together with 3 neutrals and 3 earths.
A quick confirmation indicates that and pairing of the 3 is continuous. 2 rings from 3 wires? (house seems to be wired in T&E plus singles - live and neutral are 2.5mm with a 1.5mm cpc)
I guess this is possible if 1 wire started say the upstairs ring and the other the downstairs ring and the return from both rings then ended up in the same socket before finally coming in to the consumer unit.

Does this mean that there is the possibility that one of the legs can be overloaded (as it would be if it was a radial off a 32A mcb?

Wondering if I need to recommend that the mcb is changed to a 20A until I can investigate further and trace each each cable?

 

[Sparky Ninja]

If it wasn't your PIR in the first place, the first thing you should do is investigate a situation like this for yourself. It's all down to interpretation.


Break it down into segregated legs.

 

[andekoch]

Correct it was not my PIR. I have been asked to price how much to fix it, if it needs fixing. So just bouncing thoughts around at the moment.

Currently all I have done it a quick look and confirmed that any pair (of the 3) is continuous ie 2 rings and no spur.

Am wondering if there is actually an immediate safety issue here. At the moment I am thinking not a problem, in the short term, since there is not a spur so no risk of cable overheating. Am I wrong?

 

[Sparky Ninja]

Am wondering if there is actually an immediate safety issue here. At the moment I am thinking not a problem, in the short term, since there is not a spur so no risk of cable overheating. Am I wrong?

Technically no. If you have end to end continuity on these conductors then you could presume the load will be evenly balanced.
What were the IR test results for this circuit?
I would suggest visually inspecting every socket for quantity of cables connected.
It sounds like it could have been an old radial circuit (like a spur) that may have been adjusted, and connected onto the ring main.
If it was one of my clients I would just advise on further investigation. It may take 5 minutes or 5 hours to solve.