EICR Failure - lack of continuity

[timhoward]

Please excuse my ignorance but for the Live break, can I not rely on the method I mentioned in the previous response and use that to track down where the break might be?

Normally the two live wires will be joined at the socket, so will both show live at that point anyway.
Best to follow advice above, turn power off, check the socket is dead before you open it, and look behind each one to see if there are any loose or broken wires.

 

[timhoward]

I'd add that should you fail to find a reason, and should an electrician determine the break is somewhere inaccessible then it isn't always the end of the world and there can be other approaches to resolving this.

 

[Dartlec]

Hi All,
Many of you have been assisting me with a different EICR issue. Your contribution has been invaluable.
This post is not related to that.

I had an EICR undertaken on an installation which has a 4 year old CU with 9 circuits and RCD's. This was failed due to the following:
No continuity on CPCs of socket circuit. Remaining socket circuit has no continuity on lives or CPCs. Investigation required into socket circuits as cable is undersized for circuit breaker due to no continuity.

To set expectations, I have never worked on a CU but done plenty of tasks with other parts of the residential circuit. I am also the proud owner of a Fluke T130 (with display), plug-in socket tester, fluke voltage stick and some other electrical tools. I am a DIY'er.

My question:
With the self imposed constraint of not wanting to work on the CU, would it be helpful to open each socket on the Ring and check the live cables (at least 2 on each socket unless it is spurred?) and see where I locate a dead live cable (using voltage stick and 2 pole tester)? Presumably this will indicate where the Live continuity is broken? Perhaps, I will even find a loose Live cable connection to solve this particular problem?

Secondly,
Can I use the plug in tester along with opening up each socket to try and locate the broken Earth circuit? I am struggling with this as unless I find a disconnected earth cable, I am unsure on how I will be able to locate this.

I have seen videos where you expose the tails on the CU end and use that to troubleshoot but ideally, would like to avoid this as I have never worked on a CU.

I am happy to invest in a multi-meter (My 2 pole tester does have a voltage display) if that is essential and would appreciate your advice with this please. My aim is to fix the issue and then repeat the EICR with a better outcome.

Thanks in advance

It may well need an electrician to track it down, but there are certainly steps you can do that would save them some time and you may well get lucky.

Was there a certificate when the CU was installed, if so presumably this does show continuity on the RFCs in question?

If so, have any fittings been changed or replaced since then? They might be the first place to look.

After that, checking every socket (with circuit safely isolated) and checking for proper termination may well find the culprit. Check for a loose wire, but also check that a conductor hasn't been pushed in too far so that the screw is gripping the insulation, rather than the copper.

Rodent damage or mechanical damage are probably the only likely candidates for faults outside of the fittings and that may need further investigation by someone with the right equipment to Insulation Resistance test etc.

If you have a good idea of the way the RFC is run and you can do so safely, then you could break it at what you think is the half way point, safely but separately terminate each leg - then power them up and use your plug in socket tester to see if there are any sockets that are either dead or showing an earth fault. That may then narrow down the area of concern.

Obviously only do that if you are confident in being able to safely terminate them and ensure that things are put back as they were before that circuit is put into use.

That won't rule out every possibility, but it will rule out simple solutions and potentially save an electrician several steps.

If all else fails, it may be possible to change the MCBs to convert them to radials, though that would depend on being able to isolate any leg of cable that was identifiably faulty and every remaining socket having adequate earth fault loop readings...

 

[Dartlec]

Just to add, although it can't be used for full test or certification purposes, the T130 does allow you to show continuity, If you test (circuit dead) at each circuit between the two conductors it would confirm that there is no continuity between the conductors in question - though that won't help you much.

The long lead idea won't necessarily help if everything is correctly connected at the CU, as you might be getting continuity from either 'leg' and skipping the faulty bit unless you are very sure you are testing consecutive sockets - The only way round that would be to split at several sockets and then test between the various earths and relevant lives - that would give you an idea of where the conductor is not continuous and possibly narrow it down to a room or number of sockets....

 

[buzzlightyear]

you could post your rough location. one of us may be close enough to sort it at a sensible cost.

a pkt of smokes and pkt of chrisps .

 

[brianmoooore]

you'd need to power down and safe isolate . then with both legs dissed from the CU. long lead from socket to socket on each conductor of each leg.

How about just disconnecting one leg of the RFC, putting the lid back on the CU, turning the power back on, then going around with the socket tester?

 

[telectrix]

done that a few times. sometimes a quick solution. trouble is, we sometimes tend to overthink things trhese days, doing it by the book. back in the 15th era it was a quick blast of the wind-up megger, then the bang test.

 

[Neptune]

Thanks for all the suggestion guys.
Another thought: let's assume that I am over thinking this (not the first time!) and the issue lies at the back of one of the sockets in the form a loose cable in the terminal, I was wondering how I would verify this.

Could I start by safely isolating the circuit, removing one of the sockets on the RFC and placing the probes of my 2 pole tester on the two ends of Live and then the same on Earth. Presumably this will not report continuity at this point? As a further test I could do the same on neutral and that should report continuity as the EICR hasn't said otherwise.

Once the above has been established, I could run around all the sockets and look for the loose cable. Once found and resolved, I can repeat the above test and expect to see continuity.

Is this plausible?

 

[telectrix]

i think the easiest course with limited equipment is to diss 1 leg of the ring (L,N,&E) in the CU. power up the connected leg then use socket tester round the sockets. repeat for other leg. observing safe isolation before sticking fingers in anywhere.

 

[Neptune]

Related to the above, is it the case that if I was using my Fluke 2 Pole tester on a socket across L and E and if unknown to me, the earth continuity was broken further up the ring chain, my 2 pole tester will not detect power at the socket I am testing?