RCD tripping randomly over the past few weeks

[GOLLUM]

Hi,

First post so welcome all and here goes

Over the last month the GE RCD has tripped randomly, the last time when we were asleep in bed and nothing more anoying to wake up late as alarm not gone off and all house sockets dead.

When i try to reset the rcd it will not reset until i turn off all the breakers, then it resets and i turn on the breakers one by one and away we go.

Now if it tripped when i turned the breakers back on i could isolate the circiut thats causing the problem but it does not trip.

So i can only presume its the rcd as its so random, today it tripped when i turned on the tv.

Any Idea's should i replace the rcd 1st and see if it happens again or just get a sparky in.

Thanks

 

[Des 56]

Unless you have and are able to use test gear to identify the problem
You will be peeing against the wind,best go with your own suggestion.the spark

 

[Darkwood]

To help the sparkie also try identify when it trips... is it raining (maybe outside light), as you also say its doing it night and day its possible something that turns on intermitently so check if heating is on (faulty valve) and if neither of above fits the last but not least fridge/freezer (compressor fault).
But agree it still can be hard to trace even with test gear, isolation of circuit from rcd temp' and onto rcbo may be needed to narrow the fault down.

Either way i agree with previous post, might cost a callout but probably save on the hours you lose been late for work.

 

[GOLLUM]

Thanks for info, i have isolated all outside lights and garden pump and it is still tripping so nothing outside, I did have to take a cover off the fridge a month ago to release the fan as it was frozen in ice so wether i trapped a wire i dont know so thats worth a look, is there any possibility it is the rcd as become faulty, its 15 years old now and a GE type.

 

[Top Cat]

Sounds like a neutral fault to me. If it is you definitely need a spark to sort it out!

 

[Darkwood]

Pcb - printed circuit board..... are you mixing something up here?

Rcd .. should have a test button on it if it operates when you press it it shows it works physically but you would require testing gear to see if it complies, its rare for rcd's to trip because they are faulty usually they fail to trip if they are faulty, when you say you isolated lights - have you just switched them off? RCD's monitor Neutral as well and this wont be isolated when turning switch or even mcb off, this is why this kind of problem really needs a competent electrician.

 

[GOLLUM]

Can a neutral fault just occur as we have had no wireing done for at least 5 years and that was on an extension and by approved sparky

 

[Darkwood]

May i also add - welcome to the forum, post you location we have many guys and gals on here and one may be local.

 

[StuSpiers]

Can a neutral fault just occur as we have had no wireing done for at least 5 years and that was on an extension and by approved sparky

Hah every fault I have attended the client has sworn blind no work has been done for years?

Usually forget about the new mirror they just hung into a cable.


Get an electrician to pop round - it will be sorted fairly quickly I'm sure.

 

[GOLLUM]

Pcb - printed circuit board..... are you mixing something up here?

Rcd .. should have a test button on it if it operates when you press it it shows it works physically but you would require testing gear to see if it complies, its rare for rcd's to trip because they are faulty usually they fail to trip if they are faulty, when you say you isolated lights - have you just switched them off? RCD's monitor Neutral as well and this wont be isolated when turning switch or even mcb off, this is why this kind of problem really needs a competent electrician.

Yes the test button trips the rcd but then it will not reset unless i turn off all the 6 breakers, i have tried to reset it with each one at a time but it will not unless all 6 off, then i turn all six back on and its ok till it trips again. the outside pir lamps are isolated on a switch, would it be better if i pulled out wires from switch to take out the neutral monitor situation.

 

[GOLLUM]

If there is any electrician on the forum in the leicester area who would like to come and sort out problem i would be happy just to get it sorted but i dont know any myself and dont want a cowboy coming and spending hours at my expence and making things worse hense my questions to help isolate it down so to make it easier for who comes to sort it out

 

[Darkwood]

Sounds a little strange that it wont reset unless all load is removed, its resetting may be faulty but im not too sure this is your issue with the tripping... but this is the problem; we are at an impass now and test gear is needed, you can wait and ask all night but you will only get random shots in the dark as to its cause if not educated guesses but still all guesses and really it may confuse more than help...

Il bow out here as i cant see you getting any more help with this problem without an electrician and testing gear but hope i was of some guidence.

 

[jpm646]

Could be a faulty RCD so try a ramp test or could b a slow earth leakage.
My bet is on the latter one

 

[Darkwood]

Could be a faulty RCD so try a ramp test or could b a slow earth leakage.
My bet is on the latter one

Thats a new one on me ... like to elaborate what a slow earth leak is?

 

[jpm646]

Have seen it with a few appliances where they have a earth to neutral fault usually fridges or computers but sometime on there own they aren't enough to trip RCD but some times when on together they will do or if it's one appliance it may take a while before the earth leakage trips the RCD only had this once or twice and was a ******* to fault find.

 

[PEG]

If a "cowbow" takes a very long time to relieve himself whilst out on the plains........thats a slow earth leak....

 

[Darkwood]

Have seen it with a few appliances where they have a earth to neutral fault usually fridges or computers but sometime on there own they aren't enough to trip RCD but some times when on together they will do or if it's one appliance it may take a while before the earth leakage trips the RCD only had this once or twice and was a ******* to fault find.

I get you now... computers, LED lamps etc have a design leakage, this is normal but what you are getting at is an accumulative leakage of several items with design leakage and/or fault leakage as this can creep past the approx 18mA which is then in the tripping territory of a 30mA rcd/rcbo.

There is a 'slow rise leakage' but this is less common and is a fault within an appliance normally where the leakage slowly ramps up until it trips rcd, this can be caused by heat expansion that creates earth leakage in proportion to temperature rise and can be seen occasionally in lighting ballasts for example, sorry to pull you on it i was more curious to what you meant as appose to having a dig.

 

[jpm646]

I get you now... computers, LED lamps etc have a design leakage, this is normal but what you are getting at is an accumulative leakage of several items with design leakage and/or fault leakage as this can creep past the approx 18mA which is then in the tripping territory of a 30mA rcd/rcbo.

There is a 'slow rise leakage' but this is less common and is a fault within an appliance normally where the leakage slowly ramps up until it trips rcd, this can be caused by heat expansion that creates earth leakage in proportion to temperature rise and can be seen occasionally in lighting ballasts for example, sorry to pull you on it i was more curious to what you meant as appose to having a dig.

No worries m8 i knew what I ment I just knew it to be call it a slow earth leakage

 

[StuSpiers]

If there is any electrician on the forum in the leicester area who would like to come and sort out problem i would be happy just to get it sorted but i dont know any myself

http://www.electriciansforums.net/e...your-area-local-electricians-6.html#post56078

He is from your area

post 56078

 

[Jdsparky]

My guess is a loose neutral in consumer unit(probably factory connections)....can be fine for ages and trip but not reset with load on it....fire waiting to happen as there is obviously a reason for it to trip in first place, so I would get it looked at if I were you

 

[Paul.M]

If the mcbs are on and the rcd won't reset, that could be cumulative earth leakage on start up (computers, fridge etc).

The random tripping on what you have said, the socket circuits, points towards high earth leakage just below the tripping point of the rcd until an electrical item requires more current, eg fridge or something on a timer.

It also could be damp/condensation at a socket or switch with all this heavy rain we have been getting?

As said before it needs professional investigating and I wish him good luck. Please come back and tell us how it goes.

 

[sedgy34]

My money is on the appliance he mentioned the fan clogged with ice on round it

 

[DaveyD]

I know the outside lights been turned off - but just by a SP switch?

 

[GOLLUM]

I know the outside lights been turned off - but just by a SP switch?

I have now isolated the outside light by disconecting wires from int connector so have to wait and see if it trips again, just a case of narrowing down possible cause one by one.

 

[GOLLUM]

Think i might have narrowed it down to a 2 gang socket, the socket in question just has the washing machine plugged in to it. i tried to plug in the freezer to same socket and it trips yet when i plug freezer into its original socket it fine, yet when i plug the washing machine into it it fine as well. I have a spark coming round on Monday so at least he has a starting point.

Cannot understand why it trips when i plug in freezer but not the washing machine, if it was a fault with the freezer would that not trip it when plugged into its original socket. weird

 

[GOLLUM]

It is defo the freezer causing the problem as i put both the washer and the freezer on ind RCd's and the last two trips of the main rcd the washer has been ok but freezer rcd tripped as well. So now i need to find someone to look at that,i have looked at compressor and no damp there so no idea what the problem there is.

 

[telectrix]

new freezer?

 

[GOLLUM]

You got to be kidding its a 2k usa type, and believe it or not works perfectly apart from blowing the god dam rcd. I know somwone local who services them so il just have to spend Sparkys money on that.

new freezer?

 

[Darkwood]

Remember here Gollum your confusion has arised from the simple fact you can plug the freezer in and it may not trip, but the freezer has a control circuit and may not call the compressor for hours so can be misleading, some freezers have more complex controls too so can hide the fault until certain criteria is met e.g. some models have heating coils to maintain the freezer has differing temp as the fridge all from one compressor circuit.

 

[kenny james]

have you considered having the freezer put onto its own dedicated circuit run seperately from the consumer unit?.

 

[GOLLUM]

Remember here Gollum your confusion has arised from the simple fact you can plug the freezer in and it may not trip, but the freezer has a control circuit and may not call the compressor for hours so can be misleading, some freezers have more complex controls too so can hide the fault until certain criteria is met e.g. some models have heating coils to maintain the freezer has differing temp as the fridge all from one compressor circuit.

Thanks for your replys,

Yes i understand that the appliance does use the compressor and heater on demand but it trips the RCD very random, sometimes twice in a couple of hours and as now has not tripped it since Sat evening so it must be a intermitant problem in the appliance and not everytime it is using the compressor or defrost heater.

I have contacted Smsung and am awaiting there reply.

 

[Adam Monkhouse]

Hi there,

iv just done a second fix on a house and installed a dual rcd board and the downstairs lighting circuit keeps tripping the rcd. I have done all the dead tests and everything is fine on paper but as soon as i turn the light on form any downstairs switch it trips the rcd. circuit stays on with out a lamp installed and switches all work fine but as soon as i put a load on it trips straight away!! went to first light and disconnected the leg feeding the other lights and also diconnected the leg from the DB to the first fitting put a new trailing lead straight into the db and it still tripped!! Need some help on this one guys.....head is battered!!

 

[kenny james]

hi adam,

sounds as though you have the classic problem of a borrowed neutral were the upstairs lighting shares the same neutral for downstairs lighting this will happen if you have the upstairs and downstairs circuit breakers on seperate rcd's on your dual board.

 

[Darkwood]

i would firstly divide the circuit up downstairs you may have a trapped or damaged cable, this can lay unoticed till load is applied so its down to IR tests and dividing the circuit till it stops tripping i assume from the fact you second fixed it you also first fixed too and you haven't got any crossed neutrals in the board between the 2 rcd's which again im assuming you have in the board.

 

[technospark]

See the following analysis
1.Within your distribution board there are 2 types ofd protection MCB and RCD.
2. The MCB measures load and trips out if the circuit is overloaded.
3. The RCD measures leakage to earth on any of the MCB protected circuits downstream of it.
4. The RCD monitors the current going up the positive and compares it with that returning down the negative, and discrepancy and it trips . The threshold for it to trip is 30 milliamps leaking away to earth so it does not take much.
5. Remember that although the RCD is a double pole device the MCBs are just single pole so all the neutrals downstream of the bank of MCBs in the db. are commoned.
6. The RCD will trip if the total leakage to earth exceeds 30 ma. from either L to E or N to E or a combination of the two.

Therefore a tripping problem can arise from a number of appliances on the circuits downstream of the MCBs each with a small leakage to earth giving a cumulative earth leakage in excess of 30 ma.


Also note that a double insulated appliance (no earth wire) will not trip the RCD unless the electricity is leaking away through a body!!!! or owing to water ingress.


Most electricians find this sort of problem a nightmare and try to run away from it or approach it on a trial and error basis but there is no substitute for testing out each circuit and appliance with an insulation resistance tester which applies a 500 or 1000v spike to check the appliance/circuit.

Apart from the surge arrestors the other common fault is water leaking into something, often a motorised valve, a problem within the boiler, a shower pump, central heating pump etc. If the pipework is copper look for greenish blue staining, crystallisation etc.


The type of distribution board which you probably have is notorious for this sort of thing and in the section of the industry we work in (commercial landlords/ housing associations etc) we always now use a distribution board where the earth leakage and overload protection is combined in a discrete unit for each circuit ( known as a RCBO board) In that way at least if there is a fault on one circuit then only one circuit trips off. It is less troublesome and makes diagnosis much easier. RCBOs are available for your board at around £30 each and if all else fails my next move would be to reconfigure the db with RCBOs

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