Break in ring circuit

[Tomdhu]

Just has an electrician do an EICR on a domestic property and he detected a break in continuity in the kitchen which as 6 double sockets - one of which supplies the dishwasher. The cooker is on its own MCB. All sockets test OK with a Martindale simple socket tester.

He sensibly down rated the MCB on the ring main to 20A instead of the original 32A.

My questions are ......

How difficult is it to find out where the break is by doing an impedance measurements starting at either end of the circuit.
And would your average professional electrician have plug made up to connect to his Megger to facilitate taking the readings?

And how how much would one expect to pay to have this done?

 

[westward10]

What is broken, line, neutral, cpc or all of them?

 

[Tomdhu]

I'm not exactly sure but think it may just be CPC but I will check with him in a day or so. I am no expert but with him down-grading the MCB to 20A, would this not suggest it was the line or neutral?

 

[westward10]

It would suggest that yes, it is quite straightforward to pinpoint where it is and rectifying it can be straightforward or difficult. Straightforward could be a conductor out at an accessory but difficult is a hidden break. I found one last week on the cpcs with 19 outlets took 45 minutes with continuity testing and was a cpc out at a socket.

 

[Tomdhu]

What is broken, line, neutral, cpc or all of them?

I got in contact with him and he said "no reading end to end L/L , N/N CPC/CPC".

 

[westward10]

Indicates it is probably two radial and would be easy to find assuming the breaks are all in one place.

 

[littlespark]

From the OP, the average professional electrician doesnt need to make up a plug.... they will test from the disconnected cables behind a socket. Not always easy if the sockets have been grouted to the wall during tiling.

 

[DefyG]

no reading end to end L/L , N/N CPC/CPC

Unusual to have all 3 open circuit!
Perhaps there is no break in the RFC after all and they are actually 2 radial circuits incorrectly terminated to a 32A mcb in the first place?

 

[Tomdhu]

Indicates it is probably two radial and would be easy to find assuming the breaks are all in one place.

I thought about it being two radials also which further suggests he's taking me for a sucker.

My first suspicions were when I got his invoice. I had asked for a couple of simple remedials prior to the EICR. One was reconnecting an existing fluorescent operated from 2 way switches. The other was running a 16mm earth wire from the DNO's earth block to the CU. His charges for that were eye-watering.

Going back to the so-called "broken ring" what is the easiest way to find out which sockets are on each leg of the broken ring or which radial. My guess, he could have ascertained that by separating the ends of the "ring" at the CU and then plugging in a simple Martindale socket tester. Or am I being too amateurish?

 

[PS Electrics]

I thought about it being two radials also which further suggests he's taking me for a sucker.55

Well no if it was 2.5mm on a 32A it would need down rating.

My first suspicions were when I got his invoice. I had asked for a couple of simple remedials prior to the EICR. One was reconnecting an existing fluorescent operated from 2 way switches. The other was running a 16mm earth wire from the DNO's earth block to the CU. His charges for that were eye-watering.

What is eye watering my I ask? Was there any possible complications or straight forward.

Going back to the so-called "broken ring" what is the easiest way to find out which sockets are on each leg of the broken ring or which radial. My guess, he could have ascertained that by separating the ends of the "ring" at the CU and then plugging in a simple Martindale socket tester. Or am I being too amateurish?t

No that would work. Make one leg live then make the other and go around with the tester each time.

 

[littlespark]

Finding that out is done under "dead" testing....

Every socket is taken off the wall, every leg tested for continuity to "map out" where each cable goes... ie between which sockets. From that, the location of the break can be generally worked out.
A martindale socket tester wont do it... it needs to be a professional multi function tester.... (although some things can be done with a lesser basic multimeter)

Fault finding is a costly process. It could take 5 minutes to find the problem, it could take 5 hours.


If you are not happy with what the electrician has charged you with, then there is no reason not to try someone else for the remedials

 

[DefyG]

I thought about it being two radials also which further suggests he's taking me for a sucker.

No not necessarily,
I think we all would naturally assume it to be a RFC when you see 2x 2.5's in a 32A mcb.
It would only be after formal testing as others have described that confirmation can be made as to the formation of a RFC or maybe as in this case 2x Radial circuits - but it does need proper testing which per #11 could be a five minute job or much longer!

 

[Tomdhu]

A martindale socket tester wont do it... it needs to be a professional multi function tester.... (although some things can be done with a lesser basic multimeter)

If you are not happy with what the electrician has charged you with, then there is no reason not to try someone else for the remedials

All I have is the multimeter as shown below. Can I use this?

 

[DefyG]

All I have is the multimeter as shown below. Can I use this?

It would help with continuity but is NOT a multi function tester and cannot perform all the tests as required by the IET Wiring Regulations (BS7671)

 

[Tomdhu]

OK, I am considering a DIY diagnostic strategy using my simple multi meter:-.
This will involve :-
1. Turning OFF all all power at the CU.
2. Getting a 12v battery and connecting it to the L & N wires at the first socket.
3. Using the multi meter to measure DC voltage at the next socket and so on until the end socket.
4. Do the same with L &CPC then N & CPC.
Would that work?