RCCB Breaker Tripping?

[Dave1UK]

Woke up this morning and tried to turn on the computer (work from home) wouldn't power on, checked lights they worked fine. Went downstairs to check the switchboard and only the RCCB breaker was tripped, all other MCBs on. I can narrow this down to it occurring between 06:30 - 07:30 this morning (based on Ring doorbell camera), not that is it of much use knowing this?

As soon as I flipped the RCCB on, it tripped immediately, flipped it on again and it stayed on. An hour later, the RCCB tripped again although this time along with the kitchen MCB. Few minute ago now flipped both on and it's on (currently).

This has never happened before, we haven't bought/plugged in any new appliances, definitely not between 06:30 - 07:30, as all asleep.

In the kitchen we only have 2 fridges plugged in/operating 24/7, microwave (standby) and that is literally it, everything else switched off at mains. I switched off the microwave at mains as well now, so only 2 fridges are plugged into the sockets.

Is there a way to narrow this down further/figure out what could be causing it prior to calling someone in?

Thanks.

 

[Avo Mk8]

You need to unplug things to isolate the neutral as well as the live, not just turn the switch of a plug off.
If you have an immersion heater, turn it off at its double pole switch local to it. Also unplug kettle, isolate oven etc etc.
Turning MCB's off in the consumer unit doesn't isolate neutral, so best to rely on unplugging things.
It sounds like there's a fault in the kitchen if that MCB tripped?

Hopefully you might find with everything unplugged the RCD will stay reset, and if not you will need an electrician with a tester!

Stating the obvious - things with heating elements and that deal with water are classic items for tripping RCD/ MCB's, eg: kettle, washer dryer, immersion heater, oven etc

 

[Dave1UK]

You need to unplug things to isolate the neutral as well as the live, not just turn the switch of a plug off.
If you have an immersion heater, turn it off at its double pole switch local to it. Also unplug kettle, isolate oven etc etc.
Turning MCB's off in the consumer unit doesn't isolate neutral, so best to rely on unplugging things.
It sounds like there's a fault in the kitchen if that MCB tripped?

Hopefully you might find with everything unplugged the RCD will stay reset, and if not you will need an electrician with a tester!

Stating the obvious - things with heating elements and that deal with water are classic items for tripping RCD/ MCB's, eg: kettle, washer dryer, immersion heater, oven etc

Appreciate the swift response and advice.

Will wait to see if it trips again and then actually unplug those appliances in the kitchen. We don't have an immersion heater.

I would assume it is kitchen related, however makes me wonder why the first time it didn't trip, but did second time around?

 

[littlespark]

Is any outside equipment fed from the kitchen area possibly?
Isolate that as well if you can. Water can get into anything even if they say its weatherproof

 

[Dave1UK]

Is any outside equipment fed from the kitchen area possibly?
Isolate that as well if you can. Water can get into anything even if they say its weatherproof

Nope nothing. Although we do have an outdoor flood light but that's on a different breaker I believe, unless the kitchen breaker tripping second time around with the RCCB was a false positive?

I will take a look at both in either case thanks for the reminder, however no issues as so far yet since the morning.

 

[littlespark]

no issues with the fridges still plugged in? That rules them out for now.
You could try plugging things back in one at a time.... with a couple hours inbetween... and see if it trips again.

 

[Dave1UK]

no issues with the fridges still plugged in? That rules them out for now.
You could try plugging things back in one at a time.... with a couple hours inbetween... and see if it trips again.

Ever since 3rd October (about 2 weeks ago now) there have been no issues since the initial trip and reset until yesterday again. However this time it wouldn't stay on and kept tripping every 3 minutes or so.

Only way it doesn't trip is with the kitchen MCB off. As soon as you flip it on it trips immediately or within a few minutes. I can almost guarantee it is related to the kitchen area/MCB based on the above? I removed all appliances from plugs in relation to that breaker circuit and it still trips the RCCB with nothing plugged in at all.

I have therefore kept it off for now and using an extension lead from nearby hallway to power the fridge/microwave and kettle etc when needed. Not sure whether this proves the appliances aren't the issue? Would assume so.

Is it possible the kitchen MCB unit is faulty/has developed a fault? I am aware it could be kitchen wiring being wet or whatnot but doesn't seem to make sense to me.

Also to add, the kitchen light flickers for a few seconds when initially being turned on sometimes (has been for months), no other abnormal activity in the kitchen comes to mind. However lights MCB has never tripped but wondering if that may be a sign of something electrical?

 

[davesparks]

Is it possible the kitchen MCB unit is faulty/has developed a fault? I am aware it could be kitchen wiring being wet or whatnot but doesn't seem to make sense to me.

No a faulty MCB can't cause an RCCB to trip.

If it is tripping with all appliances unplugged or otherwise isolated then there is a fault on the circuit.
Faults often don't make sense until they have been investigated.

If you find a decent electrician they will usually be able to find the fault it in a relatively short time frame.

 

[timhoward]

I can almost guarantee it is related to the kitchen area/MCB based on the above?

While it seems more likely in your case, in abstract a large load on one circuit can drive current through a neutral-earth fault (e.g. an outside light full of water) on another circuit, so it isn't a given that the MCB that causes the trip is related to the fault.

It's very frustrating to try and solve this kind of issue without test gear.
A decent electrician would be able to to say which circuit the fault is on within about 5 minutes of entering your home, and prove the problem is resolved. In cases like this with a shared RCD it is usually worth paying for an hour or two of expertise.

 

[pc1966]

I have therefore kept it off for now and using an extension lead from nearby hallway to power the fridge/microwave and kettle etc when needed. Not sure whether this proves the appliances aren't the issue? Would assume so.

If they don't trip the other circuit when plugged in the are probably OK, but it does not rule out:

• A faulty flex that is OK when away from the normal socket.
• The other socket is not RCD protected (unlikely, but not to be ignored).
• You have too much leakage from everything in the kitchen, etc, combined and so by removing a few items the total is below RCD trip threshold.

Is it possible the kitchen MCB unit is faulty/has developed a fault? I am aware it could be kitchen wiring being wet or whatnot but doesn't seem to make sense to me.

The MCB almost certainly won't be the reason. Wet sockets, junction boxes, or damaged cable(s) are all likely causes.

However, you can get difficult to pin down faults where N-E is shorting (not necessarily on the circuit you find "causes" it) and only above a certain current and on certain circuits does it trip. That is easily checked with an IR test.

Also to add, the kitchen light flickers for a few seconds when initially being turned on sometimes (has been for months), no other abnormal activity in the kitchen comes to mind. However lights MCB has never tripped but wondering if that may be a sign of something electrical?

It is not a good sign, but unlikely to be related. It could be a poor contact (switch, loose cable screw, etc) or it might be a flaky LED driver (assuming not florescent?).