RCD in consumer unit keeps popping, replaced with new one, still same issue

[Cupa]

Morning guys!

Over the weekend I noticed that the 80a RCD in my consumer unit kept tripping. The house doesn't have anything particularly power hungry - no air con, no DIY tools. It even trips in the middle of the night sometimes (I know so because the house alarm has a little fit when it detects there is no longer any power and switches to the backup battery).

I am wondering what it might be? I replaced the RCD with a second hand one from eBay, seller has 100% feedback and stated it was tested. Is that my issues (I replaced a duff one with a duff one) or is there something else I should look for?

Here's the unit with the switch pointed out. I have a multimeter at the ready to test, just tell me what to target.

 

[Bobster]

Target your phone and call an electrician in.

You wont be able to find the fault with your multi meter.

It's most likely an appliance that's faulty. Maybe a fridge or freezer. Could be a central heating pump.

Are there any patterns as to when it trips?

Edit: It will be something on one of the circuits fed from the MCBS on the right hand side.

 

[Cupa]

Hi Rob, thanks for the reply. Would you really think that it is the central heating pump? It is summer and we don't put heating on past about April unless it is really bad.

As for patterns, it seems to go off in the middle of the night at times, it is a small home and when it goes off, everybody is asleep, so aside from fridge and freezer there isn't really anything else that is on and power hungry.

It also goes off during the day sometimes, but at that point more is in use, so to me there doesn't seem to be a definitive pattern ie. goes off when something is switched on.

 

[Bobster]

The 80amp rating isn't what it will trip at, but rather how much current can safely 'flow' through it.

It will actually trip at 0.03amp. Current needed for it to trip has to 'leak' from either the live or neutral wire to earth in any circuit that it protects.

This isn't a technical explanation, but I hope it's made it more clear.

The test gear you will need to find the problem is expensive. An then you likely wont know how to use it or understand the readings. It shouldn't be a difficult task for an electrician to find the problem for you. However, intermittent faults can sometimes be a real pain to find.

What do the 4 circuits on the right of it feed?

 

[Darkwood]

As above - it could be many things and if intermittent and at random times it maybe an appliance like your fridge, it also maybe related to water ingress if you are feeding a shed or garage from that side of the board, like above can you identify the 4 circuits it effects and we can hazard a better guess.

 

[streamer]

It also looks like someone has bodged the busbar set up in the consumer unit so the RCD is feeding the two circuit breakers to the left of it too.

 

[Pete999]

How residual current device (RCD) works? - http://electrical-engineering-portal.com/how-residual-current-device-rcd-works
Might go someway to explain how an RCD opperates, as stated you probably have a faulty appliance, or a faulty circuit, best call an Electrician in to check the installation, your Multi Meter will be useless in finding the fault. Not sure I agree with the cable link acting as a Busbar for the MCBs at the far right of the Consumers Unit either. Replacement Bus bars are very cheap and easy to change, not by yourself I hasten to add. Safe isolation procedures need to be followed in order to Isolate the supply.

 

[Risteard]

Morning guys!

Over the weekend I noticed that the 80a RCD in my consumer unit kept tripping. The house doesn't have anything particularly power hungry - no air con, no DIY tools. It even trips in the middle of the night sometimes (I know so because the house alarm has a little fit when it detects there is no longer any power and switches to the backup battery).

I am wondering what it might be? I replaced the RCD with a second hand one from eBay, seller has 100% feedback and stated it was tested. Is that my issues (I replaced a duff one with a duff one) or is there something else I should look for?

Here's the unit with the switch pointed out. I have a multimeter at the ready to test, just tell me what to target.

View attachment 42840

View attachment 42841

Seriously?

 

[Cupa]

Interestingly enough, this unit was fitted about 10 years ago by a qualified NICEIC person - so not sure why a bus bar wasn't used. I should have changed that when I changed the RCB, they are only a couple of quid.

On the four MCBs to the right of the RCD, there is:

1. Electric shower (which is never used)
2. 1st floor sockets
3. Lights
4. Wall lights (not sure what that is, need to investigate)

 

[telectrix]

if that RCD is feeding the 2 MCBs to it's left, looks like they are socket rings, so that's a fair starting point. appliances. you could try switching off each one separately for a day or so ( obviously use an extension lead from the other if it turns fridge/freezer.essential equipment / off.). if the tripping stops, the fault is on the isolated circuit. this is onlyas rough and ready approach as it won't isolate a N-E fault. to be honest, previous advice to call in an electrician will save you chasing your arse and pulling your hair out.

 

[Wilko]

Several "oh dear" moments when looking into that board. Most likely the RCD wasn't / isn't malfunctioning, sorry. For safety, please put the cover back on - now .

 

[Gavin John Hyde]

Interestingly enough, this unit was fitted about 10 years ago by a qualified NICEIC person

There is so much we could say with that statement... But i will resist temptation...

 

[Octopus]

There is so much we could say with that statement... But i will resist temptation...

I think that's a bit unkind ... It's worked for 10'years.

That said a multi metre isn't going to be much help

 

[Cupa]

There is so much we could say with that statement... But i will resist temptation...

Such as?

 

[Pete999]

Such as?

4 words describe it well "Bit of a mess"

 

[Darkwood]

As it stands we can help you by suggesting what could be the cause and because you are DIYer we can only advise on possible appliances that you can unplug and try to eliminate but lets make it clear that you are playing with very dangerous voltages here and you have taken the cover off and exposed live busbar rails given the position of the main switch is ON.
The advice to you is try unplugging various items for say a week at a time overnight and see if you can clear the issue, if this fails then you need to get a competent person in with the correct meters to check your circuits.
Just remember at domestic voltages it can easily kill you even with one small shock so ensure all covers are back on and see if you can resolve this without the need to expose live parts.

I would also check to see what the weather is when it has tripped, is it windy, is it or has it been raining, these would possibly lead to possible causes like exterior lighting, garage/shed power etc etc I would also list everything that is on when it trips, are you running the washing machine overnight?.. it may trip on a particular part of the cycle, these are easier issues to verify of what can be a lengthy issue to diagnose and trace given it is intermittent.

 

[johnduffell]

those live busbars are missing some basic protection, there must be some form of plastic cover over them unless isolated. (turn off the power, put the lid back on)
you could easily rule a lot of things out with an insulation resistance tester and the knowledge to use it properly. Any decent electrician could do that for you. And also sort out the busbar and the shrouds for it.
If you want to save the cost get unplugging things and use trial an error to work it out.

 

[telectrix]

h

4 words describe it well "Hell of a mess"

corrected that for you.

 

[littlespark]

I just want to add - It doesn't matter if the appliances are turned on or not... the RCD can detect faults to earth from live or neutral.
Appliances plugged in but not switched on at the socket can cause trips.
Permanently connected equipment such as cookers or showers can trip RCD's off if the fault is on the supply side of their isolator switches.

As mentioned, intermittent faults like these are a pain for the best of us to find.

Buying anything electrical off ebay is hit and miss. Go to a local wholesaler / big orange shed, at least you'd get a guarantee.
Or employ the services of a spark.

 

[Cupa]

Thanks for the suggestions and advice guys. I will trial and error test by taking sockets out / switching off appliance and report back. Will also fix the busbar.