Open live on ring final

[garmcqui]

Hi all,

Normally I’d get a sparky in to investigate, but we are self isolating due to my son having a temperature and cough.

I went to replace a double socket with one of these super duper usb-equipped sockets in the kitchen (apparently it’ll allow the boss to charge her phone, as well as have her kettle and TV plugged in - first world problems eh?)

So, got the original socket off and, as is typical, the baby woke up and needed a bottle. So, as I was the only one in the room I flicked the mcb back (yes, with live wires exposed - I know!) on momentarily to microwave some milk for 30sec. But glad I did, as it uncovered a problem.

The microwave wouldn’t work. Joining the two separated live wires got it working again. Found the socket tester and 5 of the 12 sockets on the ring final had no juice when this ring was split at the socket.

This must indicate an open live/break in the live ring, yes? There are no sockets not working normally.

So, short of go round and take the cover off each and every socket, am I right in thinking that removing one “leg” of the ring leaving the MCB in the CU will energise sockets up to the fault?

Cheers

 

[crystal ball]

Are you sure its a ring?

 

[muffking]

What rating is the breaker?

 

[garmcqui]

32a, with both ends of the ring entering.

 

[muffking]

32a, with both ends of the ring entering.

ok, assuming the cables are 2.5mm they should be a ring then. Do you know how to check the end to ends? i.e. continuity between L to L, N to N and E to E.

Do this safely BTW, turn the main switch off if you can.

 

[garmcqui]

Yes 2.5mm cables. There was no continuity on the live ring when tested at CU. Didn’t check neutral or earth but can do.

To update on what I’ve done, I removed one end of the ring from the breaker. Roughly half the sockets energised. Checked with just the other end of the ring connected, the other half of outlets energised. So, this at least narrowed it down to two outlets that could be the issue - 2 FCU’s in the utility room.

Removed front of one - all looks fine, old red and black wires all secure. On the second, however, it’s a little more complicated - looks like the ring has been extended to add a 3rd FCU and a double socket at some point, as there is a mixture of red/black and blue/brown.

Annoyingly, disturbing this FCU seems to have got the ring working again. But that suggests there’s a loose connection somewhere, which I need to find.

will add some pics

 

[garmcqui]

so, don’t like the look of new to old wires wrapped in blue tape and heading left out of the box towards the new socket and FCU.
What you think?

 

[garmcqui]

Not liking it at all (don’t even think they’re crimped! No grommets on box either.

(unsure why images have rotated on uploading - sorry!)

think I might add a mother 25mm pattress box to the left of this FCU, with just a blanking plate on the front, and join the cables using wago’s behind - that do?

 

[muffking]

View attachment 187007think I might add a mother 25mm pattress box to the left of this FCU, with just a blanking plate on the front, and join the cables using wago’s behind - that do?

Doing that would certainly give you the access you need and cover the missing plaster. I'd add 20mm grommets at the entry/exit points to protect the cable too.
It may just be that there's a join where the blue tape is, or the cable has come loose at the terminal.

 

[garmcqui]

Ok thanks all.

 

[securespark]

Could it be that the RB cable has been taped up as disused and a new BB cable installed to replace it?

 

[garmcqui]

Could it be that the RB cable has been taped up as disused and a new BB cable installed to replace it?

No, the cables were joined by twisting them together and covering in electrical tape. Can’t believe someone would do that on a socket ring. Not even sure it was this that was causing the problem, could have been a loose connection at the back of the FCU.

worrying thing is, we moved in here last year and it’s probably been like that since then. That means that a single 2.5mm cable was supplying a 3kw kettle, 2.5kw oven, ~2kw dishwasher, and ~2kw washing machine - many of which are often on at the same time - and no protection other than a 32A breaker (and an RCD)! I make that 9.5kw, or 40+ amps

 

[securespark]

It'd be highly unlikely everything would be demanding maximum current at the same time.

 

[garmcqui]

Agreed, with thermostatically controlled devices it’s rare. But it could happen.

Next plan is to try and find out who did the wiring - was it the previous owner, or a dodgy sparky they employed? Hmmmm

 

[muffking]

I'd like to think that no genuine spark did that. I wouldn't be able to leave it like that, it would play on my mind. An easy fix for the sake of a few wagos or JB and maybe a length of cable.