L-E reversed and low voltage on RFC

[diced carrots]

Trainee here so it's likely I've got my wires crossed!

I've got a small unoccupied rental property which had a rewirable fuseboard which my work colleague (fully qualified spark) and I replaced the other day with an 8 way RCBO board, surge protected. He did the board change while I replaced some sockets with USB charging sockets.

Initial end to end testing on the Ring Final indicated that there was a break in the ring somewhere, so we swapped out the 32a breaker for a 20a. All circuits were holding fine on the RCBO's after we went home on Friday evening. The plan was that I would come back today to investigate the broken ring, carry out some testing and to label up the board.

So, when I got back to the property today I plugged my socket tester into a socket and it indicated Live Earth Reversal. I pulled off all the sockets to check they were all wired correctly and they all looked good. Using my MFT I tested the voltage between L-N and it showed 60v, between N-E voltage was 190.

Any ideas?

 

[Pete999]

Trainee here so it's likely I've got my wires crossed!

I've got a small unoccupied rental property which had a rewirable fuseboard which my work colleague (fully qualified spark) and I replaced the other day with an 8 way RCBO board, surge protected. He did the board change while I replaced some sockets with USB charging sockets.

Initial end to end testing on the Ring Final indicated that there was a break in the ring somewhere, so we swapped out the 32a breaker for a 20a. All circuits were holding fine on the RCBO's after we went home on Friday evening. The plan was that I would come back today to investigate the broken ring, carry out some testing and to label up the board.

So, when I got back to the property today I plugged my socket tester into a socket and it indicated Live Earth Reversal. I pulled off all the sockets to check they were all wired correctly and they all looked good. Using my MFT I tested the voltage between L-N and it showed 60v, between N-E voltage was 190.

Any ideas?

Done any r1 r2 testing?

 

[ipf]

Sounds like a neutral problem...and if you've a break in the ring, where's the place to start?
What are the ring continuities?

 

[diced carrots]

Done any r1 r2 testing?

Not yet. Was called home to other duties before I could get stuck in!
[automerge]1582477287[/automerge]

Sounds like a neutral problem...and if you've a break in the ring, where's the place to start?
What are the ring continuities?

I've been right through the property all sockets off and terminals checked. I found one that was pumped full of silicone but I replaced that one with a new socket and the fault remained.

Also, all sockets worked until we changed the board. The previous tenant had damaged a few sockets and had removed one, but I think I've accounted for all of that.

 

[snowhead]

I think the answer is obvious, but did you test before the board change, if so were the L-E, L-N, N-E results the same as now?

And have you checked the connections for the Ring in the new C.U?

 

[marconi]

diced carrots: a clear opening post - well done Sir.

 

[telectrix]

socket testers will often show L-E reversal if you have a floating N. that's where the fault is. a poor connection somewhere on N. do a end-end on N and then track it down by splitting the ring.

 

[static zap]

L-N and it showed 60v, between N-E voltage was 190.

If the voltages are stable with socket tester present ,
and they add to aprox 250 .
Something is floating up , due to presence of socket tester.
One of your notional ref points is actually a mid point voltage !
Think potential divider.

(2nd half of post self supressed -involved wagos ,a socket and fly cables --stay safe )

 

[Strima]

Had the exact same last week, broken neutral and disconnected CPC.

 

[diced carrots]

Thanks all for your help, it's much appreciated!

I've been back to the property this evening and tested the circuit.

• End to ends were 0.64 (r1) and 1.11 (r2).
• L-N tests at sockets ranged between 0.30 and 0.36.
• L-CPC ranged between 0.39 and 0.48
• Zs 0.66

When I screwed the conductors back in to their terminals in the CU the original fault rectified itself. I suspect there might have been a loose connection at the Neutral terminal?