Fault finding ring final RCBO

[Conteh]

Done a condition report on a old mains board, everything good apart from ring final, got 0.55 nn 33.7ll and 3.8 on ee, changed board to main switch and rcbos, carried out a full accessory swap on all sockets and fuse spares in house, found some bad practice, twisted lives, n and earth's, no sleeving all things to add to the high resistance problem. Retested board end to end 0.55nn 0.90 ee open ll. So changed the 32 rcbo to 2x16a rcbos broke the ring in half having 5 sockets on one side and 6 on the other. Rcbo trips! Any idea what I'm doing wrong?

I know the information isn't details but fire away with questions.

Help ?

 

[westward10]

Do both rcbos trip or just the one.

 

[Baddegg]

Bit confused with what tests you’ve done mate?...and are you saying you found a fault and then changed the board without finding the fault first??
Ignore me just read ya post properly...

 

[Pete999]

Done a condition report on a old mains board, everything good apart from ring final, got 0.55 nn 33.7ll and 3.8 on ee, changed board to main switch and rcbos, carried out a full accessory swap on all sockets and fuse spares in house, found some bad practice, twisted lives, n and earth's, no sleeving all things to add to the high resistance problem. Retested board end to end 0.55nn 0.90 ee open ll. So changed the 32 rcbo to 2x16a rcbos broke the ring in half having 5 sockets on one side and 6 on the other. Rcbo trips! Any idea what I'm doing wrong?

I know the information isn't details but fire away with questions.

Help ?

What type of wiring is employed?

 

[buzzlightyear]

32 rcbo to 2x16a rcbos broke the ring in half having 5 sockets on one side and 6 on the other. Rcbo trips! Any idea what I'm doing wrong?

yeah n/e fault possible ,you have swapped the 32 amp for 2 radials .yes. i hate it when some body's trying to wind up a elastic band on a pc or phone .lol.

 

[Baddegg]

Junction box somewhere?

 

[buzzlightyear]

changed board to main switch and rcbo

got 0.55 nn 33.7ll and 3.8 on ee

what was the r1& r2 then .

 

[Pete999]

Could be mate

 

[westward10]

@Conteh it may help if you joined in.

 

[Pete999]

what was the r1& r2 then .

Got to be summat wrong with the discrepancy with LL and NN readings, bad connection in the sockets, bad connection during testing, who knowns from afar? or the competence of the tester.

 

[littlespark]

You changed all the sockets, and the end to end tests got worse?

 

[Baddegg]

@Conteh it may help if you joined in.

I was just about to type that! ?...this is the worst game in the world when the op disappears!

 

[James]

so L to L was 33 ohms, changed all the sockets and now it is open circuit end to end?
could it have been a poor connection somewhere giving a high resistance originally, now you have changed all sockets etc and its gone open circuit maybe a wire has come out of a terminal when you pushed sockets into boxes??

i would be checking the ring out with a wander lead.

edit, in the space of 4 minutes, 4 of us have basically had the same thoughts!!!

 

[snowhead]

Assuming he/she comes back.
When you changed all the sockets did you check the ring as you were working your way around to prove it is a ring or remove all the old sockets and check and prove each leg to locate the fault if there is one?

 

[Conteh]

Guys and girls I'm sorry for my poor attendance to class, having said that.

Just 1 rcbo trips, I connected L and N at 1 side of the circuit and simply tested continuity with the plug in lead, done the same test on the other side of the ring, I have found the break on the LL but repairing it isn't possible without damage to carpets or walls that the client isn't prepared to do, it could be a junction box. Yes. So I decided to split the ring into two radials, but 1 rcbo trips and can't understand why.

I did do I end to end on LL and got 33.7 ohms before the mains change, I then done a full accessory swap and now have open ring, I then checked all the sockets I swapped and there doesn't seem to be a break behind them.

I didn't check for a ring when installing the accessories, i will say that all the lives, N and E were twisted together before my works. The possibility of a break after the fact is high would you agree? I just don't know if to continue with finding the fault giving the clients limitations, or finding why 1 rcbo trips when splitting the ring.

Cheers

 

[James]

I think you first need to confirm exactly what is connected to what.
Draw the circuit out and it may well become apparent

 

[Conteh]

I think that's what I need to do. Disconnect at mains board and individually Bell out what's what. I'm back there Monday. I will update whatever the outcome.

??

 

[pc1966]

Most likely there is some link between what you think are now two separate radials, and probably one RCBO is tripping faster than the other.

But hopefully if you can go back and do a more thorough check of the extent of L & N on each circuit you will find the problem. Also worth verifying there is proper isolation of L & N to all other circuits and to CPC/Earth.

 

[Conteh]

Thanks for all the help guys, outcome was that the ring had a dead short N-E from the lounge to the kitchen.
I took all the sockets off and disconnected all connections at the board, identified and mapped the wiring by way of continuity. I then was left with two unidentified cables between two sockets. I done a IR on this leg and had a connection between N&E. Left this leg disconnected. Reconnected all other sockets splitting the ring into two radials. Unfortunately the client lost a socket rom 1 side of the radial but i managed to get a full test. ?? Thanks for the advice and help.