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...