Likely cause of Consumer unit tripping?
Discussion
Our CU keeps tripping. The left hand side of the board has fuses/trip switches for kitchen, ground floor sockets, door bell, first floor lighting and then a larger one which is RCD Controlled Circuits.
It’s the larger one that trips and it’s an 80a Hager.
It went off early this afternoon when we had a few TVs going, washing machine was on and the Xmas tree lights but not much else. Then it went again this evening when the oven was on and pretty much immediately after I turned it back on.
The yellow “earth fault indicator” was highlighted and goes off when I flip the switch up.
It’s tripping now every 45/60mins or so now, with nothing but the living room tv on. I’ve now turned all the downstairs sockets off including switched fused spurs (yea, including the fridge!) to hear if it trips again.
I replaced a socket with a double about a fortnight ago but it’s been working fine since (it’s on a spur which was switched off for the past few times it’s tripped) but can’t think of anything that will have changed any time recently.
I guess at this time of year you’d expect it to be crazy Christmas lights but we have 2 small sets on the tree and the rest are battery operated fairy lights so I don’t think it’s that!
Any idea of likely causes before I call an electrician to find what may be something stupidly simple?
It’s the larger one that trips and it’s an 80a Hager.
It went off early this afternoon when we had a few TVs going, washing machine was on and the Xmas tree lights but not much else. Then it went again this evening when the oven was on and pretty much immediately after I turned it back on.
The yellow “earth fault indicator” was highlighted and goes off when I flip the switch up.
It’s tripping now every 45/60mins or so now, with nothing but the living room tv on. I’ve now turned all the downstairs sockets off including switched fused spurs (yea, including the fridge!) to hear if it trips again.
I replaced a socket with a double about a fortnight ago but it’s been working fine since (it’s on a spur which was switched off for the past few times it’s tripped) but can’t think of anything that will have changed any time recently.
I guess at this time of year you’d expect it to be crazy Christmas lights but we have 2 small sets on the tree and the rest are battery operated fairy lights so I don’t think it’s that!
Any idea of likely causes before I call an electrician to find what may be something stupidly simple?
I’ve just watched a YouTube video from a very articulate guy on how the circuit breakers only break the live and still allow flow through the neutral (makes me glad I always turn the full board off when I do anything!)
I’ll have another look at the new socket (it was a single to double replacement, not a new socket as such) but I’d be embarrassed if that’s the fault!
We’ve had a such a mix of appliances on whennit trips that I’d be surprised if it’s an overload issue (but then I’m not an electrician!) but it’s gonna be a royal pain if it’s a random leak somewhere!
I presume when you turn a switched fused spur off you’re still only turning the live off and as such the earth/neutral could still be a problem? If so, I hope it’s the new sockets that’s the problem!
I’ll have another look at the new socket (it was a single to double replacement, not a new socket as such) but I’d be embarrassed if that’s the fault!
We’ve had a such a mix of appliances on whennit trips that I’d be surprised if it’s an overload issue (but then I’m not an electrician!) but it’s gonna be a royal pain if it’s a random leak somewhere!
I presume when you turn a switched fused spur off you’re still only turning the live off and as such the earth/neutral could still be a problem? If so, I hope it’s the new sockets that’s the problem!
Sheepshanks said:
AlmostUseful said:
Our CU keeps tripping. The left hand side of the board has fuses/trip switches for kitchen, ground floor sockets, door bell, first floor lighting and then a larger one which is RCD Controlled Circuits.
It’s the larger one that trips and it’s an 80a Hager.
Just a point, as the way you've written that is as if they're separate - the RCD is protecting the same circuits as the circuit breakers. The circuit breakers protect against over-current and the RCD for earth faults. It’s the larger one that trips and it’s an 80a Hager.
Thanks! Very detailed response there. I’ll check the socket I do when it gets light. Have just come downstairs and it’s obviously tripped again, the saving grace is that downstairs lights is on the right hand circuit and not the left one that keeps tripping and all the upstairs stuff is also fine!
I put the rcd back on and it tripped within a minute just now. I’ll try again with the MCBs off and gradually turning them on. Then call and electrician, I’m not taking the front off the CU - this isn’t my ball game!
I put the rcd back on and it tripped within a minute just now. I’ll try again with the MCBs off and gradually turning them on. Then call and electrician, I’m not taking the front off the CU - this isn’t my ball game!
That looks useful! I’ve decided so far (on little other than the GF sockets tripping quickly) that everything can be on except the GF sockets, that loop would also most likely be the oldest wiring in the worst condition - for a bit of history our house is 1930’s and used to have timber flooring but the grand piano went through the floor so they were replaced with concrete.
Lots of the wiring is surface mounted but some is underground - I could see that being a problem (albeit it’s been fine the past 20 odd years that it was done!) so Sod’s law it’ll be some underground stuff we cant get to that will be nackered!
Might get one of those testers to have a look, and also go around and look at any areas I can think of that might be dodgy before calling anybody out. I can run power downstairs with an extension lead to keep the fridge going in the event that it drops again, and if I can’t find anything glaring i’ll call a spark We’ve got about 3 who live within 200yds so are spoilt for choice!
Lots of the wiring is surface mounted but some is underground - I could see that being a problem (albeit it’s been fine the past 20 odd years that it was done!) so Sod’s law it’ll be some underground stuff we cant get to that will be nackered!
Might get one of those testers to have a look, and also go around and look at any areas I can think of that might be dodgy before calling anybody out. I can run power downstairs with an extension lead to keep the fridge going in the event that it drops again, and if I can’t find anything glaring i’ll call a spark We’ve got about 3 who live within 200yds so are spoilt for choice!
I’ve left one ring (ground floor sockets) off since about 7 am, and it’s been fine since then.
Does that suggest the problem isn’t on any of the other rings? The oven and microwave are wired in behind units and I can turn the fused switches off but can’t unplug them without removing them completely.
Currently the kitchen is all on (plugged in, not literally in!) and the fridge and kettle are in use.
The lights all work.
The ground floor sockets are used for the router, two TVs, 2 skyQ boxes and a few lamps (rarely on) and all these are off (but plugged in, sockets turned off)
Ref the damp, it could be an underground connection on the ring or the wiring in the loft (probably two most likely problem areas, but on different circuits)
We’ve had 4 hours with no outage now so i’ll Maybe get to a whole day and the turn the final ring on I expect it to trip.
Does that suggest the problem isn’t on any of the other rings? The oven and microwave are wired in behind units and I can turn the fused switches off but can’t unplug them without removing them completely.
Currently the kitchen is all on (plugged in, not literally in!) and the fridge and kettle are in use.
The lights all work.
The ground floor sockets are used for the router, two TVs, 2 skyQ boxes and a few lamps (rarely on) and all these are off (but plugged in, sockets turned off)
Ref the damp, it could be an underground connection on the ring or the wiring in the loft (probably two most likely problem areas, but on different circuits)
We’ve had 4 hours with no outage now so i’ll Maybe get to a whole day and the turn the final ring on I expect it to trip.
What I’m hoping for is that I turn it back on and it trips, then I know it’s *something* on that ring, then I can unplug everything and turn it back on and start to close the problem down somewhere. Be kind of annoying if I turn it on and it’s all fine and then doesn’t it doesn’t trip for a week!
1. We do have a dimmer, it’s been in for about 6 months - it buzzes a bit and we never use it preferring a lamp in the corner. I’m going to replace it with a switch anyway but I doubt it’s the cause.
2. We’ve been it all day, the whole house has been functioning since 7am without the ground floor socket ring on.
3. I’ve just unplugged everything from the downstairs sockets, only a few things are plugged in (the playroom runs off a single extension so only 1 to unplug)
4. With nothing plugged in the circuit tripped. Numerous times instantaneously with the breaker being flipped up it turned the ground one off.
I know a few places that I’d be concerned about damp so will check them out and replace items as necessary and then get my spark in.
Cheers for the advice all
2. We’ve been it all day, the whole house has been functioning since 7am without the ground floor socket ring on.
3. I’ve just unplugged everything from the downstairs sockets, only a few things are plugged in (the playroom runs off a single extension so only 1 to unplug)
4. With nothing plugged in the circuit tripped. Numerous times instantaneously with the breaker being flipped up it turned the ground one off.
I know a few places that I’d be concerned about damp so will check them out and replace items as necessary and then get my spark in.
Cheers for the advice all
Out of interest, I’ve been reading more about this and a few people mention across the web that if the main breaker trips immediately when you turn the other switch on that it’s either wiring or the bracket itself may be faulty.
I have a spare breaker (the ones for individual rings) would it be worth swapping a known working one to check if the same ring trips just to disprove that it’s the breaker switch?
I have a spare breaker (the ones for individual rings) would it be worth swapping a known working one to check if the same ring trips just to disprove that it’s the breaker switch?
To be fair I did actually mean the MCB (if that’s the breaker that’ serves the individual rings) but might get the RCD done anyway. Have a last minute holiday morning from work today so going to have a look for some damp damage or something before getting the electrician in. If nothing else at least I can expose some things which mean I won’t be paying an electrician to break things!
Found a few green wires (you know how copper goes when it gets wet) so cleaned them up and put the fixings back together but no joy, also a few loose wires in various sockets and off to Spurs - they were obviously in place a the time but came out when I pulled the socket plate away from the back box - resecured and put back together - time for super Alex my electrician to take over now I think.
I’m sure you’ve all been dying for an update...
Electricians, 2 and an apprentice have just left. They’ve had all the face plates off, checked voltage and resistance I guess and have found a few things.
1. Most importantly, it’s nothing I’ve done when at the property!
2. One of the sockets in the playroom is actually from the old boiler and is on a different ring and so it works. We can take a feed off this to give us 2 sockets and the play room will be fine.
3. The socket and spur in the hall which feed the downstairs WC light have been isolated and now work. So we’ve got power for the doorbell and vacuum cleaner, and light to pee by (behind a door, we’re not savages!)
4. There is an absolute dead short and sod all resistance to some wires which run under a retro fitted concrete floor slab with no access. And as such the living room as a minimum needs rewiring. This shouldn’t be the most difficult job in the workd as we’ve worked out a way to get there from the consumer unit without destroying the whole house even though they are on opposite sides of the property.
5. I have no idea how much today will cost me but it’s a b
d that it’s so close to Christmas!
All in all it’s not a bad outcome, we can muddle on until we can fit in the disruption and cost of rewiring.
Thanks for tuning in.
Electricians, 2 and an apprentice have just left. They’ve had all the face plates off, checked voltage and resistance I guess and have found a few things.
1. Most importantly, it’s nothing I’ve done when at the property!
2. One of the sockets in the playroom is actually from the old boiler and is on a different ring and so it works. We can take a feed off this to give us 2 sockets and the play room will be fine.
3. The socket and spur in the hall which feed the downstairs WC light have been isolated and now work. So we’ve got power for the doorbell and vacuum cleaner, and light to pee by (behind a door, we’re not savages!)
4. There is an absolute dead short and sod all resistance to some wires which run under a retro fitted concrete floor slab with no access. And as such the living room as a minimum needs rewiring. This shouldn’t be the most difficult job in the workd as we’ve worked out a way to get there from the consumer unit without destroying the whole house even though they are on opposite sides of the property.
5. I have no idea how much today will cost me but it’s a b
d that it’s so close to Christmas! All in all it’s not a bad outcome, we can muddle on until we can fit in the disruption and cost of rewiring.
Thanks for tuning in.
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