Why would circuit breaker trip every few hours?

Risteard

vacheron wrote: »

For example, your RCD will trip if the earth leakage current exceeds 30mA. If there is a fluctuating earth leakage current of around 28mA average occurring then this will sometimes nudge over 30mA and trip the device.

Actually, an RCD will trip anywhere between half of its rated residual operating current and the full rated residual operating current, i.e. a 30mA RCD can trip on any imbalance between live conductors exceeding 15mA (so long as it does not need to exceed 30mA) and will be in compliance with the Standard (BS EN 61008 / BS EN 61009 usually these days.

scarletjim

Ben84: Thanks for providing the required clarification on my misuse of terminology - you are quite right, it is not 'tripping', as no switches have ever gone down, it is just losing power every 4-10 hours, but then regaining that power when I flip all the switches up and down 5 mins later to reset it.

You mention unplugging unneeded devices - last night before going to bed, I turned off all the RCD-related circuits except the kitchen sockets (as I want the freezer to run until I absolutely need to turn that off). It went off again during the night. Presumably that means one of 3 problems:

1. The freezer, microwave or other kitchen appliance is causing the problem - but then surely the switch would actually trip, i.e. switch down? Or is that not necessarily the case with a leaking earth problem?

2. The RCD / Fuse box has a problem.

3. There is a problem in the wiring as you have suggested. If this were the case, given that I had all other circuits turned off, would this mean that the problem must relate to the wiring / sockets in the kitchen? Or could it relate to another part of the house even though those switches were all turned off?

One other query on your theory - given that I had all other circuits turned off all night, surely that should mean much less current, and therefore less overheating? Though I suppose if the problem was with a kitchen wire / socket then those were still fully functioning.

beckstar1975 - thanks for the suggestion, that must have been horrible for you. I guess that could apply here, but I think unlikely, as the kitchen is the only circuit I've not elininated by turning them all off at various times, and I don't see how rats could get to the kitchen wiring...

Looks like we're finally making some king of progress though... I'm nearly at the stage where I can exclude 90% of areas / appliances before my electrician comes...

Ben84

scarletjim wrote: »

Ben84: Thanks for providing the required clarification on my misuse of terminology - you are quite right, it is not 'tripping', as no switches have ever gone down, it is just losing power every 4-10 hours, but then regaining that power when I flip all the switches up and down 5 mins later

Flipping the switches off and on doesn't perform any kind of reset with any breaker I know of. However, if using the switches immediately restores power each time, that makes me wonder if the bad connection is inside the consumer unit, as the motion may affect it.

scarletjim wrote: »

You mention unplugging unneeded devices - last night before going to bed, I turned off all the RCD-related circuits except the kitchen sockets (as I want the freezer to run until I absolutely need to turn that off). It went off again during the night. Presumably that means one of 3 problems:

1. The freezer, microwave or other kitchen appliance is causing the problem - but then surely the switch would actually trip, i.e. switch down? Or is that not necessarily the case with a leaking earth problem?

Given what you've described, I strongly suspect your appliances are fine.

The household wiring is a complete, continuous circuit itself, and the appliances plugged in to it are smaller circuits attached to to it - but not part of it. So, an appliance may develop a fault, but it cannot break a connection in the mains circuit as it's not part of it, so it won't stop power reaching other appliances. A more serious appliance fault will trip a switch in the consumer unit, but that's not what's happening here.

Earth leakage is a whole other issue that wouldn't cause any of the problems you're having.

scarletjim wrote: »

2. The RCD / Fuse box has a problem.

This is possible as it's part of the household circuit.

scarletjim wrote: »

3. There is a problem in the wiring as you have suggested. If this were the case, given that I had all other circuits turned off, would this mean that the problem must relate to the wiring / sockets in the kitchen? Or could it relate to another part of the house even though those switches were all turned off?

The turned off circuits are physically disconnected and can't do anything when you flip their breakers off. I now suspect the kitchen circuit too.

scarletjim wrote: »

One other query on your theory - given that I had all other circuits turned off all night, surely that should mean much less current, and therefore less overheating? Though I suppose if the problem was with a kitchen wire / socket then those were still fully functioning.

It does indicate a problem in the kitchen circuit or consumer unit, so I'd tell the electrician about this as it would be a likely place to start from what you've found.

scarletjim

Update: So, last night I switched off the fridge freezer, and there was no cut out of power overnight... It could just be that it hasn't happened yet, as at times it has taken 10+ hours, other times less than 4 hours, but it could be that it is the fridge freezer that is causing the problem. It looks fine, both compartments appear to be working (when it's switched on I mean obviously) - what could be wrong with it? Could there be something wrong that causes the power to cut out even though it seems to be working fine? Is there anything I can (safely) check myself? Or is it over the the professionals now? If so, do I need an electrician, or now I know what it is, do I actually need an appliance repair person who is familiar with this brand (Maytag)? Is it likely to be repairable, or will I have to replace it?

Heedtheadvice

NO to last question. Your logic is not correct.

The fridge freezer would not cause the power to 'go off' on the circuits unless it had an earth leakage problem which should trip the RCD -and you write that does not happen.
It all still points to an intermittent fault in a connection somewhere in the circuits or consumer unit.

Get that electrician in to do the diagnostic checks. It should not take long to find the issue and then locate where (may take longer if the fault is in an inaccessible part of the house wiring) but the diagnostic tests can pinpoint what the problem is.

You are now just making guesses and trying to apply some logic (great that you have gathered what is background info to date and done what you can but you must have reached the limit of what is possible now) but measurement and inspection is the way forward :T Might be just something as simple as a loose screw........I have one of those :cool::o;)

scarletjim

Heedtheadvice wrote: »

NO to last question. Your logic is not correct.

The fridge freezer would not cause the power to 'go off' on the circuits unless it had an earth leakage problem which should trip the RCD -and you write that does not happen.
It all still points to an intermittent fault in a connection somewhere in the circuits or consumer unit.

I'm sure you're right (I'm certainly the amateur here after all!) but please could you explain a bit further? In my logic, if the power has gone off every 4 to 10 hours since Wednesday, but stops doing so only when I leave the fridge freezer off, surely the fridge freezer (or wiring feeding it) must be related to the problem? If not, why would switching the freezer off stop the 'power cuts' happening?

(Caveat: Of course I'm not certain yet that the above is the case - will see if the power goes off between now and tomorrow morning with the freezer off (I'm told it will be ok for 48 hours when absolutely full, so 24 hours should be no problem)).

coffeehound

Something I once read on an American site is that where the 'fault' current is low, a circuit breaker can trip internally without actually moving the external breaker switch.

So although the breaker doesn't look as though it has tripped, it will reset when its switch is cycled off and back on again. Could that be happening here?

brightontraveller

I’d say 1 % chance wiring fault as described by others 90% an item with a motor e.g fridge freezer, boiler etc with the rest being pests, faulty rcd etc leave it off 24 hrs RCD stays on there’s your culprit …. What you have to loose (more than likely is food in freezer) against cost of call out and testing

CathA

Have you tried to plug the fridge in another socket? If it still trips it's one thing less to tick off the list of possibilities.

phil24_7

To test your fridge/freezer. Use an extension lead and connect it to another power circuit.