Socket Ring Main keeps tripping

[scotzman]

Hi, need some help please.

I have a separate consumer box for my kitchen, with a separate ring main (had an extension built)

The electric set up was done by a mate who is a spark (he isnt available) and the CU was set up accordingly to cope with all demand.

Today, and out the blue the CU tripped or more accurately, the left hand RCD supporting the sockets. I reset, and about 10 seconds after, tripped again.

I have a fitted kitchen so have isolation switches for all the main appliances, removed anything plugged in and reset....nothing tripped. Plugged in fridge, pop...unplugged and reset. Switched on Microwave, fine until actually trying to cook something then trip. There does not seem to be one thing that is causing it to trip, just any type of load is causing it to pop.

I have had this setup for over 2 years and no issue and if I leave the socket fuse off, everything else is fine.

I have an identical 63amp RCD in the CU so have switched, seems to make no difference. Only thing that is confusing is that the RCD on the right will trip when pressing test, but the one on the left wont. After swapping them, its the same, left RCD wont trip on the test button.

UPDATE: i have tried all manner of switching on and off and thought I would update. I have a comms cupboard set up with various amps, virgin box, xbox etc. So I have managed to start up the following

1) TV via socket
2) Virgin box via socket
3) Xbox via socket
4) Microwave via isolation switch
5) Dishwasher via isolation switch
6) Oven via isolation switch
7) Cooker hood via isolation switch
8) Gas hob (sparker) isolation switch
9) LED lights via socket

Both microwave and oven trip the rcd when actually used to cook.

Things that trip the RCD immediately;

1) Fridge Freezer ia isolation switch
2) Tumble Dryer via isolation switch
3) Coffee Machine via socket
4) Hot Tap via socket


Any suggestions welcome on this Bank Holiday weekend!

Thanks in advance.

Dougie

 

[flameport]

Most likely is a fault between neutral and earth on one of the circuits.
It may be on the kitchen sockets circuit, but it could be on one of the others.
Without test equipment this will be next to impossible to locate.

 

[scotzman]

Thanks for the reply Flameport. Is it commom for a fault to arise in a fairly static environment? Nothing has been touched or moved since install.

Cheers

Dougie

 

[EFLImpudence]

Just to clarify:

Do you mean that the test button does not work on whichever RCD is on the left side?

 

[scotzman]

Just to clarify:

Do you mean that the test button does not work on whichever RCD is on the left side?[/QUOTE

Yep, tried to test it before and after swapping and both left hand RCDs will not test, both bothright RCD's will.

 

[delmel]

Even A hungry rodent can cause a problem anytime if the like a curious nibble. Faults can be a challenge to track down hope you get lucky and find sooner that later

 

[bernardgreen]

There does not seem to be one thing that is causing it to trip, just any type of load is causing it to pop.

Which suggests that the fault is not on the ring of sockets but is a Neutral to Earth fault on one of the other circuits that the RCD supplies. Switching OFF the MCB for the circuit will not clear the fault as the MCB does not open circuit the Neutral.

 

[scotzman]

Which suggests that the fault is not on the ring of sockets but is a Neutral to Earth fault on one of the other circuits that the RCD supplies. Switching OFF the MCB for the circuit will not clear the fault as the MCB does not open circuit the Neutral.


Thanks.Bernard, apologies for what may be a stupid question, if I remove the MCB and disconnect the feed to the other two circuits, and connect them one at a time, would that work in identifying the problematic circuit?

Secomdly, if it is the socket circuit, would I be able to diagnose the location of the fault by multi-metering socket by socket along the main looking for a drop?

Thanks

Dougie
View attachment 191838

 

[bernardgreen]

The only way to be certain of finding the fault is to disconnect both Live and Neutral at the consumer unit to fully isolate the circuit and then measure the insulation resistance of the circuit. That is resistance between Live to Earth and then Neutral to Earth.

When a faulty circuit has been identifies by insulation resistance testing it should be divided into sections ( both Live and Neutral disconnected ) and insulation resistance testing applied to each section. Sometimes a visual inspection will find the fault. A common one is damp in or damage to an outside lamp fitting.

Not all "electricians" are aware that a Neutral to Earth fault on an "isolated" lighting circuit ( MCB switched OFF ) can result in the RCD being tripped by a load on a different circuit.

 

[AndyPRK]

If desperate, you can disconnect the N at the CU for unimportant circuits on that RCD or Alternatively circuits you suspect and see how you go. Turn mcb off too

If you suspect an appliance, run an extension lead to a
Socket on the other RCD is see how it behaves

Or keep your fridge going

 

[scotzman]

If desperate, you can disconnect the N at the CU for unimportant circuits on that RCD or circuits you suspect and see how you go.

If you suspect an appliance, run an extension lead from it, to a
Socket on the other RCD is see how it behaves

thank Andy, I have plugged in the available appliances, fridges, hot tap that I can get access to. All working fine! The others are all built in behind the kitchen units hence the isolation switches for microwave, oven, dishwasher etc.

I will have a go at disconnecting the other circuits and see if that has an effect and go from there!

 

[scotzman]

All sorted fault was with the cable to my disconnected hot tub cable that has managed to arc.

thanks for all the help folks, very much appreciated!!

 

[crystal ball]

Is the test button working now?

 

[scotzman]

Is the test button working now?

Yep, working a treat

 

[crystal ball]