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Rcd Pattern Of Tripping


PaddyW

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I had a new consumer unit installed when my kitchen was replaced about 2 years ago and I have had a RCD problem ever since on the upstairs circuit.  I have been told that upgrading to RCDs has meant greater sensitivity and this may be picking up an old wiring problem.

 

When we try to use the vacuum cleaner upstairs the RCD trips.  This happens every time.  Occasionally this has also happened when a hairdryer was used but this is not all the time.  Everything works fine downstairs and in the kitchen etc.  The circuit that trips only has sidelights, computer, printer etc. plugged in – nothing heavy usage.  We worked round the problem by using the vacuum cleaner upstairs with an extension lead from downstairs. 

 

The problem has now escalated and is getting harder to cope with.  Yesterday the RCD tripped when someone used the shower.  This is the first time this has happened.  The shower is wired separately on a different circuit and continued to work.  Since yesterday the RCD trips every time someone uses the shower.

 

I would be grateful for any advice on things that I can check before I have to call in the professionals.

 

Many thanks

PaddyW

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Paddy, did the installer of the new fuseboard give you an Electrical Installation Certificate with all the tests results filled out, and if so what were the IR (insulation resistance) values noted?

 

To be honest there is very little you can do without test equipment and knowledge/experience

 

Sounds like you have a neutral to earth fault on the circuits protected by said RCD

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My immediate thought was what we call a borrowed neutral on your landing light ...but that doesn't sound right after reading on .

 

Theres a possibility of the upstairs sockets neutral being wrongly connected in the board.

Could have socket connected  wrong  N & E crossed.

 

Can you tell us how many RCDs are in your new board  ..is there one at each end ? 

 

And just to make sure .......are you getting mixed up between an RCD and an MCB at all ?    

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My immediate thought was what we call a borrowed neutral on your landing light ...but that doesn't sound right after reading on .

 

Theres a possibility of the upstairs sockets neutral being wrongly connected in the board.

Could have socket connected  wrong  N & E crossed.

 

Can you tell us how many RCDs are in your new board  ..is there one at each end ? 

 

And just to make sure .......are you getting mixed up between an RCD and an MCB at all ?    

 

 

Not sure I agree with that statement as the hairdryer only occassionally trips the RCD!

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I'm thinking just one socket , plug in  vacuum , hairdrier and it trips  , just guesswork without being there.  

 

The reason I put the ring neuts connected wrongly ...I'm sure we had that happen and it didn't always trip .

 

Could be just an over sensitive RCD  , they need testing . 

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I had a new consumer unit installed when my kitchen was replaced about 2 years ago and I have had a RCD problem ever since on the upstairs circuit.  I have been told that upgrading to RCDs has meant greater sensitivity and this may be picking up an old wiring problem.

 

When we try to use the vacuum cleaner upstairs the RCD trips.  This happens every time.  Occasionally this has also happened when a hairdryer was used but this is not all the time.  Everything works fine downstairs and in the kitchen etc.  The circuit that trips only has sidelights, computer, printer etc. plugged in – nothing heavy usage.  We worked round the problem by using the vacuum cleaner upstairs with an extension lead from downstairs. 

 

The problem has now escalated and is getting harder to cope with.  Yesterday the RCD tripped when someone used the shower.  This is the first time this has happened.  The shower is wired separately on a different circuit and continued to work.  Since yesterday the RCD trips every time someone uses the shower.

 

I would be grateful for any advice on things that I can check before I have to call in the professionals.

 

Many thanks

PaddyW

 

 

Right...

1/   With the new fuse box you should have had a 3 page electrical installation certificate...

The back page should have a list of every circuit on the fuse box and a whole bunch of test results, (Live & dead tests & RCD tests) for every circuit.

 

2/ These tests if done correctly should have identified any potential wiring problems..

Broken / missing earths,  Polarity,  The condition of the cable insulation, the condition of the incoming supply and its earth, The correct operation of the RCD's..

etc.. etc...

 

3/ If an appliance is going faulty it can trip an RCD,  But as a general rule it would trip any RCD in ANY socket not just upstairs sockets..

 

4/ The symptoms you describe sound to me like a trapped wire in the back of an accessory, where the cable insulation is slightly crushed but not completely cut away.

So only during higher currents is there sufficient to cause a break down to earth.

 

5/ A neutral to earth fault on any circuit that shares the same RCD could cause the RCD to trip when any one of those circuits are in use. e..g  So an appliance plugged in could allow current to flow to earth via the neutral of the shower circuit..

 

6/ Without some proper test equipment, Insulation Resistance tester, Continuity tester, RCD tester etc..  there is not very much you can do.

 

7/ Unlike MCBC which detect high overload currents, RCDs detect very very small amount of electric current flowing to earth to prevent electric shock...

So you are not looking for a dead short to earth. 

 

 

Was the kitchen wiring and fuse box done by some kitchen fitters, or by a proper electrician???

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I think you might be chasing multiple faults. For instance "since yesterday the RCD trips every time someone used the shower" might meand that since yesterday the shower itself has developed a fault.  Start by turning the shower off at it's isolating switch, not just with the switch on the shower itself.

 

The real solution is to get an electrician in and he will test everything.

 

If you really don't want to do that, then unplug EVERYTHING from all your sockets and experiment with what appliance trips it when plugged in as the ONLY thing plugged in at any one time.

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most likely N-E fault. and it doesnt always have to be on the circuit thats used when it trips either, so its possible to still be sockets thats faulty even though it trips when shower is used

 

might be an easy fix, might not be, but youre going to get nowhere without proper test equipment to identify what the fault is so you can then start looking for it

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Think the shower tripping is a coincidence and you should get it checked out before you use it again!

where are you located maybe someone here can help?

@spec loc you been wiring up cats again? You'll get in trouble for that!

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I was thinking the fault night be a N-E fault on the shower, hence asking if they just turn it off at the shower or at the isolator.

 

I also suspect a new CU at the same time as the kitchen was fitted may, just may, not have been tested or documented properly.

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I would be grateful for any advice on things that I can check before I have to call in the professionals.

 

Many thanks

PaddyW

 

Welcome to the forum.

I don't think there is much more you can do, without someone actually being there to visually check how the circuits are wired, what the previous test certificates (if issued) say, or doing some correct re-testing  of the circuits and the RCDs. Any fault finding is a process of elimination. It could be an appliance fault, a wiring fault, an over sensitive RCD, or combination of multiple causes. Three devices leaking 10ma each would work correctly on their own, all together they would cause the RCD to trip. So just saying one appliance generally works OK doesn't mean that appliance is not part of the problem. The first thing you have got to eliminate out of the equation is the overall condition of the circuit cables and the standard of the wiring. Correct testing should either eliminate this from the equation or highlight any particular areas of concern on a circuit or two. Realistically you need a component electrician to come round and test your circuits. There is a slim chance an immediate fault could be found quite quickly. But it is more likely to need at least half a day to a full day of testing and or isolation of sections of wiring, to fully test the integrity of the installation. Dependant upon labour rates in your area, and travel costs, number of circuits, time needed, I would hazard a guess at anywhere from £125 to £250 should cover a comprehensive test. It may need more than one visit.  You also have the catch 22 where the electrician who replaced the fuse box may be the quickest to retest and identify the problem, but had they done a correct job in the first place in my opinion you would not have the problem. A second electrician would take longer as they would need to retest and work out what the first electrician had done. Please keep up informed of what you find.

 

Doc H.

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