Ring main troubleshooting

The neutral to neutral bar clearly comes from RCD so those two wires just above the MCB's must feed the RCD from the isolator.

With so little on the CU I would start with Isolator or RCD off and test there to start with, with enough power to trip an MCB the problem has to be bad, so no need of insulation tester, multi meter good enough, with all unplugged and MCB's off three readings, earth to neutral, earth to line, and line to neutral, should all be open circuit, but will guess line to neutral is short circuit, if neutral to earth short circuit then likely RCD would have tripped not MCB, but although we would normally test both the line and neutral, if one can remove the neutral wires then one can likely locate the area of fault by disconnecting neutral in centre socket, and neutrals in CU and work out what side fault is.
 
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ericmark said:
The neutral to neutral bar clearly comes from RCD so those two wires just above the MCB's must feed the RCD from the isolator.

With so little on the CU I would start with Isolator or RCD off and test there to start with, with enough power to trip an MCB the problem has to be bad, so no need of insulation tester, multi meter good enough, with all unplugged and MCB's off three readings, earth to neutral, earth to line, and line to neutral, should all be open circuit, but will guess line to neutral is short circuit, if neutral to earth short circuit then likely RCD would have tripped not MCB, but although we would normally test both the line and neutral, if one can remove the neutral wires then one can likely locate the area of fault by disconnecting neutral in centre socket, and neutrals in CU and work out what side fault is.
Click to expand...
Understood & thank you very much. Will proceed shortly.
 
DIYWell said:
Sorry, question from the audience ...

Looking at that photo, is the supply coming into the isolator then feeding the three breakers, or is it feeding the RCCB which then feeds the breakers?
Click to expand...
I don't think one can tell by just looking at the photo.

There are two neutral bars (implying that the RCCB is 'meant' to be there, and protecting some, but not all,of the circuits), so it's very possible that the left hand three MCBs (not currently used) are fed via the RCCB, but that the three right-hand ones (currently used) are fed directly from the Main Switch (i.e no RCD protection).

Kind Regards, John
 
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ericmark said:
The neutral to neutral bar clearly comes from RCD so those two wires just above the MCB's must feed the RCD from the isolator.

With so little on the CU I would start with Isolator or RCD off and test there to start with, with enough power to trip an MCB the problem has to be bad, so no need of insulation tester, multi meter good enough, with all unplugged and MCB's off three readings, earth to neutral, earth to line, and line to neutral, should all be open circuit, but will guess line to neutral is short circuit, if neutral to earth short circuit then likely RCD would have tripped not MCB, but although we would normally test both the line and neutral, if one can remove the neutral wires then one can likely locate the area of fault by disconnecting neutral in centre socket, and neutrals in CU and work out what side fault is.
Click to expand...
Can now use hand OK.
Just as you predicted Eric, I did as as advised & found fault following your excellent advice.
Everything now working correctly. Very grateful indeed for your kind help. I learnt a lot too.
 
ebee said:
That does not make sense
Click to expand...
"martygturner said:
In all our efurbs and rentals we are having rings taken out to form radials on RCBO cu's. in the properties with rings eicr's were constantly showing up with faults some real, missing conductor some just whatever...dc voltage being a particular bug bear from usb sockets. At least with a radial if a socket is missing a conductor its fairly easy to spot the break or fault."

I am just wondering if we will get a further explanation of that statement?
 
I have been a fan of radials over ring finals for many years. If I were to rewire my gaff, I would not entertain ring finals at all.
 
securespark said:
I have been a fan of radials over ring finals for many years. If I were to rewire my gaff, I would not entertain ring finals at all.
Click to expand...
Fair enough, I`m happy with either/or . Both have pros and cons.
PS - I do come from an era where ring finals were quite the norm, so perhaps a little biased
 
EFLImpudence said:
Fits in with what? I thought they - rings - were quite the norm still today.
Click to expand...
They're still still very common, and probably exist in a substantial majority of curret domestic installations.

However, I would suggest that, in recent years there has been an increasing tendency to install (in new-builds or during re-wires) radials rather than rings.

I don't think that many such discussions were around before a decade or so ago, prior to that, I suspect that few people were even considering anything other than rings.
 
D

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