RCD tripping on new Consumer Unit

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I have had a new Hager CU fitted - done at the same time as a Solar installation. All MCBs, RCDs are Hager. This is a split load CU - 7 MCB's on one side covered by a 30 ma RCD (no problems on this side) and 6 MCB's on the other side covered by a 30 ma RCD (RCD has tripped twice on this side).

On the side that trips I have :-
2 lighting circuits both on 6A MCB
1 sockets circuit on 16A MCB
1 Solar circuit (I think input from inverter) on 20A MCB
1 sockets circuit on 32A MCB
1 cooker circuit on 32A MCB

The RCD has tripped 3 times since it was fitted about 6 weeks ago. No MCB's trip, just the RCD. The RCD trips appear quite random - I can't pin it down to any event.

Can anyone suggest reasons why this could occur? Can it be caused by a faulty appliance?

When the RCD has tripped, it is possible to push the switch back up again within a few minutes - it trips straight away if I attempt to push switch up within a few seconds of the trip occuring.

The house is 1960's built. The old CU was fuse wire type.

Just wondering how to detect the problem? and possible solutions

1) can a less sensitive RCD be fitted or will that be potentially dangerous?
2) if RCBO's fitted instead of MCBs, then should the RCD be taken out? (I think this should then just trip the citcuit where the fault is so it would at least pin it down - is it OK just to replace MCB's with RCBO's on 1 side of the box?)

I an not an electrician and would be very grateful for any pointers here...

All work was (and will be) carried out by qualified electricians and I have received the NAPIT cert. for the install.

sorry about the lengthy post but I wanted to include as much info as poss..


thanks in advance for any help......
 
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RCDs trips can be down to a number of reasons, the fact that you have had regular trips within a short period from install widens the field of possibilities.
I would first suggest the next time it trips, to remove all loads form live and neutral, then reset RCD and introduce each load at a time back to the circuits, this could possibly lead you to an appliance/equipment fault.
If the RCD will not reset with all loads removed, then the fault lies with the installation and the installer should be called back.
It would be possible to fit RCBOs in to the unit, but they would need to be independent from the existing RCCB.
You require a minimum of 30mA, any greater than that and it is non-compliant.

My money is on the cooker!
 
You require a minimum of 30mA, any greater than that and it is non-compliant.
You mean MAXIMUM 30 mA

If it is an appliance then it should be easy to find but only if both LIVE and NEUTRAL to the appliance can be disconnected. Switching OFF at the socket will only disconnect the live lead and a neutral to earth fault will still trip the RCD.

If no appliance is identified then you will need to have a full insulation resistance check carried out to locate the fault.

A neutral to earth fault can trip an RCD even when the MCB for that circuit is turned OFF


Some electricians do not realise this is possible.
 
As bernardgreen rightly says line - earth faults are easy but neutral - earth faults are hard to trace.

For current to flow in a conductor there has to be a voltage differential and with the modern TN-C-S earthing system when no items are drawing current there is no voltage differential between earth and neutral.

As one increases the load so the differential increases so a fault with a toaster plugged in but not in use can cause the power to trip when the kettle is used.

In the main it happens to items on the same circuit and often using RCBO's will isolated the fault to one circuit but not always.

The regulations state:-
314.1 Every installation shall be divided into circuits, as necessary, to:
(iii) take account of danger that may arise from the failure of a single circuit such as a lighting circuit.
(iv) reduce the possibility of unwanted tripping of RCDs due to excessive protective conductor currents produced by equipment in normal operation.

With so many circuits on the same RCD is could be said it's non complainant specially as the lights are on that RCD. It's a grey area but I would not recommend fitting so many circuits to same RCD. So I would contact the installer and say you have a fault. Unless you like me have emergency lighting to put lights and sockets on same RCD is not really a safe procedure.
 
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Personally, I'd forget about trying any self-diagnosis and call the electrician back who installed it six weeks ago!
 
In the main it happens to items on the same circuit and often using RCBO's will isolated the fault to one circuit but not always.
The RCBO on a circuit with a neutral-earth fault will trip when there is a heavy load on another circuit. It can be un-nerving to switch on one RCBO and see another one trip.
 
Personally, I'd forget about trying any self-diagnosis and call the electrician back who installed it six weeks ago!
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All work done by NAPIT registered electricians is guaranteed for six year for workmanship.


Call him back to sort it out. If he cannot/won't then you have a route through NAPIT for it to be resolved.

If you mess with it then he would quite rightly say that its now your problem.
 
All work done by NAPIT registered electricians is guaranteed for six year for workmanship. Call him back to sort it out. If he cannot/won't then you have a route through NAPIT for it to be resolved.
Would that guarantee still apply if (as presumably is fairly likely) the RCD tripping is due to an item of the OP's equipment/appliances? I would have thought that it was only the work done (i.e. the 'installation') that was guaranteed.
If you mess with it then he would quite rightly say that its now your problem.
As far as I can see, no-one has suggested any 'messing' beyond unplugging appliances in an attempt to identify the cause of the tripping. That surely would have no impact on the guarantee?

Kind Regards, John
 
All work done by NAPIT registered electricians is guaranteed for six year for workmanship.

Means the work he has done. Obviously he's not responsible for other influences.

However, if he changed the consumer unit then he should have carried out an EICR on the existing installation. This could/should have revealed issues such as bad IR readings that could be the cause of the RCD trip.

Whatever, the first port of call is to get him/her back as you are not satisfied.
 
All work done by NAPIT registered electricians is guaranteed for six year for workmanship.
Means the work he has done. Obviously he's not responsible for other influences.
As you say, obviously. If he were called out and it transpired that the problem related to the consumer's appliances, and not to any of the work he had done, I would imagine that he would charge for his time wouldn't he?
However, if he changed the consumer unit then he should have carried out an EICR on the existing installation. This could/should have revealed issues such as bad IR readings that could be the cause of the RCD trip.
Issues in the wiring,yes, but one hopes that the IR tests wil not have been undertaken with the OP's appliances in circuit.
Whatever, the first port of call is to get him/her back as you are not satisfied.
Would it not be better, as others have advised, to first try to eliminate as many as possible of the OP's appliances as a cause (which requires no knowledge, skill or 'messing'), hence possibly avoiding possible electrician's charges?

Kind Regards, John
 
I have had a new Hager CU fitted - done at the same time as a Solar installation. All MCBs, RCDs are Hager. This is a split load CU - 7 MCB's on one side covered by a 30 ma RCD (no problems on this side) and 6 MCB's on the other side covered by a 30 ma RCD (RCD has tripped twice on this side).

On the side that trips I have :-
2 lighting circuits both on 6A MCB
1 sockets circuit on 16A MCB
1 Solar circuit (I think input from inverter) on 20A MCB
1 sockets circuit on 32A MCB
1 cooker circuit on 32A MCB

Not sure id be happy with that solar circuit feeding back into a RCD bank like that.
 
I would first suggest the next time it trips, to remove all loads form live and neutral, then reset RCD and introduce each load at a time back to the circuits, this could possibly lead you to an appliance/equipment fault.


My money is on the cooker!

Thanks for all for the replies. I am trying to get the electricians back but not succeeded so far!

To remove all loads from live and neutral - does this mean unplugging all appliances? Is switching off the cooker at the isolating switch ok? (The cooker is about 2 years old).

Is there any other way of testing appliances for the sort of problem which could cause an RCD trip? (I guess not...or I would need specialist equipment...)
 
To remove all loads from live and neutral - does this mean unplugging all appliances? Is switching off the cooker at the isolating switch ok? (The cooker is about 2 years old).
Yes, unplug where possible, otherwise use an isolator switch (which will usually be 'double pole', hence disconnecting both love and neutral).
Is there any other way of testing appliances for the sort of problem which could cause an RCD trip? (I guess not...or I would need specialist equipment...)
There are tests which can be done, although they are not necessarily foolproof in a case like this. However, as you suspect, they require specialist equipment.

Kind Regards, John
 

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