# RCD keeps tripping with no MCB switched on



## LD2520

hi people,
I'm new to the site so be gentle.

I am helping to rewire a house. Its quite a big house so has a 15 way split board. The right hand side is working perfectly but the left hand RCD won't stay on!!!

None of the MCBs are on but the RCD just wont stay on. I'm back there next weekend. Managed to wire everything up to the right hand RCD. so all circuits are working.

sorry if I'm not making any sense but its late and I've been at it for about 14 hours (not this problem but running cables wiring sockets and switches etc..)

Any ideas?


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## HARRY304E

LD2520 said:


> hi people,
> I'm new to the site so be gentle.
> 
> I am helping to rewire a house. Its quite a big house so has a 15 way split board. The right hand side is working perfectly but the left hand RCD won't stay on!!!
> 
> None of the MCBs are on but the RCD just wont stay on. I'm back there next weekend. Managed to wire everything up to the right hand RCD. so all circuits are working.
> 
> sorry if I'm not making any sense but its late and I've been at it for about 14 hours (not this problem but running cables wiring sockets and switches etc..)
> 
> Any ideas?


What country are you posting from?


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## LD2520

im posting from the UK


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## Meadow

LD2520 said:


> hi people,
> I'm new to the site so be gentle.
> 
> I am helping to rewire a house. Its quite a big house so has a 15 way split board. The right hand side is working perfectly but the left hand RCD won't stay on!!!
> 
> None of the MCBs are on but the RCD just wont stay on. I'm back there next weekend. Managed to wire everything up to the right hand RCD. so all circuits are working.
> 
> sorry if I'm not making any sense but its late and I've been at it for about 14 hours (not this problem but running cables wiring sockets and switches etc..)
> 
> Any ideas?


 
Sounds like either a defective RCD or a wire cross down steam from the branch breakers.

Did you do a megger continuity test on each branch circuit? Neutral, ground and hot should all register no continuity between each other with everything unplugged and all light witched off.


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## maddhatter

What brand RCD?

One of my colleagues came across a similar issue just this week with a cheap and nasty RCD... wouldn't switch on unless mains were present.


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## HARRY304E

LD2520 said:


> im posting from the UK



Good man:thumbsup:

Welcome to the forum..:thumbup:


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## LD2520

Thanks Harry 304e
Maddhatter, its a Wylex board

Meadow please explain what you mean by branch breakers. All circuits have been IR tested and they are all spot on (>2MOhm) 

Ive heard that a dud RCD is extremely rare. With no lives connected into that side of the board it still wouldnt stay on.


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## ispark

Hi LD2520

You either have a neutral from the left hand rcd connected to the right hand rcd(or vice versa) or you have a neutral to earth fault on the side that the rcd will not stay on.


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## LD2520

Thanks ispark
I will double check the neutrals and earths. Thanks for all your help people i will let you know how it goes.


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## LD2520

All sorted problem was a faulty socket faceplate. Had a crack through the earth plate. So there was a break in the earths.


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## hardworkingstiff

LD2520 said:


> All sorted problem was a faulty socket faceplate. Had a crack through the earth plate. So there was a break in the earths.


I wish I spoke this language so I could understand what happened. It sounds interesting.


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## frenchelectrican

LD2520 said:


> All sorted problem was a faulty socket faceplate. Had a crack through the earth plate. So there was a break in the earths.





hardworkingstiff said:


> I wish I spoke this language so I could understand what happened. It sounds interesting.


 
Hardworkingstiff.,

I will translate for you.

He did sort out the conductor issue and found the receptale faceplate and have a crack on ground plate ( or screw ) so there is a break of ground connection.

Hope that help you with that.

Merci,
Marc


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## hardworkingstiff

frenchelectrican said:


> Hardworkingstiff.,
> 
> I will translate for you.
> 
> He did sort out the conductor issue and found the receptale faceplate and have a crack on ground plate ( or screw ) so there is a break of ground connection.
> 
> Hope that help you with that.
> 
> Merci,
> Marc


Does that mean that the grounding means depends on the faceplate? If so, that sounds .................... dangerous.


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## frenchelectrican

hardworkingstiff said:


> Does that mean that the grounding means depends on the faceplate? If so, that sounds .................... dangerous.


 
Oui et Non depending on what faceplate they do use over in UK but over here in France the earth connections will go to the earth connector screw or front wired devices but for the cover screws they are allready bonded thru the earth plate so that will be not a issue so it will be simair to the North Americian receptels.

Merci,
Marc


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## LD2520

Hi sorry my explanation wasn't clear

On the back of a double socket face plate there are usually 2 earth connections one for the right and one for the left socket. These are connected by a piece of copper. This copper plate was separated in the middle. 

It is not dangerous because we usually use what's called equipotential bonding which is earth cables that go between metal pipes, baths, etc... This is so if there's a fault you won't get a shock because the earth cable draws the power to earth so you don't. 

I hope this helps. Please feel free to ask any questions and I will explain. Or try at least


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## great68

LD2520 said:


> Hi sorry my explanation wasn't clear
> 
> On the back of a double socket face plate there are usually 2 earth connections one for the right and one for the left socket. These are connected by a piece of copper. This copper plate was separated in the middle.
> 
> It is not dangerous because we usually use what's called equipotential bonding which is earth cables that go between metal pipes, baths, etc... This is so if there's a fault you won't get a shock because the earth cable draws the power to earth so you don't.
> 
> I hope this helps. Please feel free to ask any questions and I will explain. Or try at least


That did not cause your problem unless the broken earth (ground) was touching the Neutral 
If it was not then I reckon you had a trapped neutral under a faceplate screw which you inadvertently freed whilst looking


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