RCD trips when on holiday

Section62

jrawle said:

bris said:

Not sure what goes on in your head but thats the wildest theory for a trip I have ever seen.

Why would a cistern even overflow by not being used?

The inlet valve may not shut off fully, meaning water slowly drips in, overfilling the cistern. Normally, this would not matter as the level returns to normal after a flush, but if you are away, it will reach the overflow, or if you are unlucky and that's blocked, actually overflow into the room.

It wouldn't necessarily need a blockage.  Just a plumber who didn't connect the overflow pipe properly, or has made dodgy solvent weld joins on the pipe between the toilet and the discharge point.  That could easily result in drips of water entering an electrical fitting, or coming into contact with a bare conductor.

Alanp

I wouldn’t let the RCD go on holiday…🤭

Ectophile

It could even be something that gets damp when you've switched everything off, but normally stays warm enough to drive the damp away.

Random RCD trips aren't always easy to track down.

HoolyNI

Thanks for your input everyone. Don't think its mice, damp or the neighbour. Have had bother with trips years ago but rarely since I had the kitchen done up. Have suspected an oversensitive RCD being tripped when the fridge or freezer switches on in middle of the night but cant understand why it doesn't happen when we are here....

fenwick458

victor2 said:

Maybe you could find a good electrician to check if it has any earth leakage at all in normal use, or if there is any significant leakage generally?

you could find the best electrician in the world but tracing an intermittent fault is very labour intensive, if the fault is intermittent they would have to wait there until it occurs, could get expensive with an electricians hourly rates...
about 10 years ago I had to track down a fault like this, and found many things wrong which I fixed and each time was sure that would fix it, but every time the nuisance tripping kept on occurring at random times.
in the end I fitted a consumer unit full of RCBO's (which were £30 each so this was a last resort), and the problem was very quickly traced to a 110v transformer a few weeks later.
to put this in perspective the parts alone cost £350 which is 7 times what a 10 way dual RCD consumer unit cost at that time so customer was not keen to do it at all was was insistent on just "finding the fault " 
consumer units with RCBO's are the norm now, and much cheaper, so my advice would be just upgrade the consumer unit and then it'll do the fault-finding for you

Chickereeeee

fenwick458 said:

victor2 said:

Maybe you could find a good electrician to check if it has any earth leakage at all in normal use, or if there is any significant leakage generally?

you could find the best electrician in the world but tracing an intermittent fault is very labour intensive, if the fault is intermittent they would have to wait there until it occurs, could get expensive with an electricians hourly rates...
about 10 years ago I had to track down a fault like this, and found many things wrong which I fixed and each time was sure that would fix it, but every time the nuisance tripping kept on occurring at random times.
in the end I fitted a consumer unit full of RCBO's (which were £30 each so this was a last resort), and the problem was very quickly traced to a 110v transformer a few weeks later.
to put this in perspective the parts alone cost £350 which is 7 times what a 10 way dual RCD consumer unit cost at that time so customer was not keen to do it at all was was insistent on just "finding the fault " 
consumer units with RCBO's are the norm now, and much cheaper, so my advice would be just upgrade the consumer unit and then it'll do the fault-finding for you

Yes, I had split CU where the sockets tripped randomly. Sometimes months with no trip, sometimes two in two weeks. Annoying, but worrying if it happened on holiday, as the fridge and freezers would defrost. As a temporary measure, I had an rcbo put in just for the fridge/freezer. This worked, in as far as the RCD still tripped, but fridge/freezer stayed on.

However, I later replaced the CU with all-RCBOs (with spare for electric car charger in the future) and have had zero trips since. So maybe original fault was a faulty rcd, or something  in the CU.

fenwick458

Chickereeeee said:

However, I later replaced the CU with all-RCBOs (with spare for electric car charger in the future) and have had zero trips since. So maybe original fault was a faulty rcd, or something  in the CU.

sounds about right, I've seen that loads too. in thats scenario the nuisance trips will be caused by cumulative earth leakage, imagine if theres an upfront RCD feeding 8 circuits, if each circuit has 2mA leakage (about right nowadays as all electronics leak current to earth and it's quite common for all households to have complex electronics on al circuits rather than just simple resistive loads) then 2 x 8 =16mA total you are already close to the 25mA that most RCD's seem to trip at.
any slight fluctuation and it'll trip.
put each circuit on it's own RCBO and that won't happen

HoolyNI

I have a main consumer board under the stairs with separate fuses for different circuits throughout the house, including a fuse for the garage. There is also a separate fuse board out in the garage although it doesn't have a trip fitted. Could fitting a trip to that maybe solve the problem?

It's almost as if the less electric being used the more likely a trip is to occur, although a few nightlights being on when we are here is the only change in usage compared to when we are away...

victor2

HoolyNI said:

I have a main consumer board under the stairs with separate fuses for different circuits throughout the house, including a fuse for the garage. There is also a separate fuse board out in the garage although it doesn't have a trip fitted. Could fitting a trip to that maybe solve the problem?

It's almost as if the less electric being used the more likely a trip is to occur, although a few nightlights being on when we are here is the only change in usage compared to when we are away...

Fitting an RCD to a circuit not currently covered by your existing RCD is not going to help your problem.

Your difficulty is the RCD only trips when you are away, so it isn't a situation you can readily repeat!

You use a lot more than a few nightlights when you are present, compared to when you are away. You take things in and out of the fridge, cook meals, use hot water, heat the house as required, switch lights on etc. etc.

In businesses, electrical equipment has to be PAT tested. I don't know if you can get someone to test the appliances that you leave on when away? It's been a few years, but I recall they have a bit of kit they plug devices into and it shows if they're safe to use. Of course, IF your fridge/freezer is the culprit, it may be tested and look fine - it depends on what it is doing when tested.

Can you get an electrician to run a new feed to where the fridge is, on a circuit with its own RCD? Problem might disappear then, or if an RCD still trips when you're away, you'll have an idea if it is or isn't the fridge. Bit of a long shot, but may not be too expensive to try. Know any friendly electricians?

Or maybe move the fridge so that it runs off the garage circuit and put an RCD enabled adapter into the socket it will be using? Did think of suggesting running the fridge off an extension from the garage (still with its own RCD adapter), but lashing that up and then leaving the house is probably far too dangerous and risky. Could start a fire, burn the house down and the insurance refuse to pay out, and that's before any safety aspect is considered!

Chickereeeee

HoolyNI said:

I have a main consumer board under the stairs with separate fuses for different circuits throughout the house, including a fuse for the garage. There is also a separate fuse board out in the garage although it doesn't have a trip fitted. Could fitting a trip to that maybe solve the problem?

It's almost as if the less electric being used the more likely a trip is to occur, although a few nightlights being on when we are here is the only change in usage compared to when we are away...

It's probably clearer if you avoid the word 'fuse' and instead use MCB and RCD (and RCBO). If your set-up is similar to as mine was, all 13a circuits were on individual MCBs, but covered by one RCD. This includes the 13a circuit to the garage, within which there is a small CU, equipped with MCBs but no RCD. So, a fault in the garage would trip the RCD. Correct?

If so, adding an RCD to the garage CU may or may not improve matters. I think it would depend on exactly how quickly the fault was detected by the two RCDs, and how quickly they react. You may get either one, or even both, tripping. Better to replace the MCB assigned to the garage with an RCBO and bypass the RCD in the house CU.