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dazza001

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Hi folks

I have recently discovered that a plug socket in my kitchen has no earth connection.
The actual earth cable is there and is connected at the socket however when I test for continuity it is open.
It seems like it is a spur as it only has one cable(twin & earth) but I can not find where it has been taken from, (its not from the nearest socket on the ring anyway or any other sockets that are nearby) and it is definatley on the ring circuit because when I disconnect the ring fuse the socket is dead.

I have traced the cable so far and it goes behind the plaster (in metal conduit) and upwards toward the ceiling(concrete floor downstairs).
So I suspect it has been taken from a junction box upstairs underfloor or something.

Anyway I do not want to go lifting floorboards upstairs or anything so I was wondering if it was possible to connect a new earth from the socket to the metal pipework or to another socket earth.

Cheers in advance for your replies
 
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Cirrus

  • Thread Starter Thread Starter
  • #2
Dazza, I am a litle confused about the picture you are paiting. If the socket is a 'spur' then fine but your twin and earth cable should have a live & neutral and cpc (earth). Just make sure that each of these conductors is terminated properly. If you have a metal back box you can also earth the back box for good measure by taking a 'fly' from the earth terminal on the socket to the earth lug on the back box but obviously, if you have a fast fix plasterboard box then this isn't necessary.

Does this help?
 
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TonyM58

  • Thread Starter Thread Starter
  • #3
Dazza,

Ok, you say this is a spur, and the fact that it goes off with the ring. If the junction box is hidden then that contravenes the regs because all screw connections have to be accessible for inspection, maintnenace etc, but hat is the least of your problems!!!

Interesting when you say test for continuity, between which two points? If you measured 230V between the phase and the earth at the socket, then the earth has a complete path back. The real test would be to measure the Zs (earth fault loop impedence) at the socket, this would be a good test of the earth cable, but you would need a loop tester to do it.

Ok assumin you really havent got an earth - and you are suggesting brining the earth off another socket? A sensible option would be to disconnect the incoming cable to the socket and safely terminate it to a chock block inside the pattress, then brining a complete new twin and earth cable from the socket that you were going to bring the earth off. That way it stays as a spur and would be safe.

Assuming of course that the earths are complete at ALL of your sockets, I would be suspicious now and start testing everything........

best of luck

Tony
 
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adamh

  • Thread Starter Thread Starter
  • #4
have.a.look.in.the.upstairs.sockets.for.a.start.after.testing.8etween.phase.and.earth.for.230v.and.getting.nowhere!!why.dont.you.want.to.lift.the.floor8oards.i'dsay.this.is.the.easiest.option!!and.why.earth.the.8ack8ox.when.more.than.likely.the.screws.will.do.that!!!
 
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dazza001

  • Thread Starter Thread Starter
  • #6
Cheers for your replies,

The two points that I tested the continuity of the earth was between the copper pipes of the plumbing system and the earth connector at the socket and also the earth connector of a socket nearby and the socket in question.
(Ps. I have only tested the continuity with a multimeter as I do not own an Earth loop impedance tester although this still allowed me to find an open circuit in the earth wiring.)

I have tested all the other sockets on the ring (with a socket tester)and they all show correct wiring and earth connections except this one.

This all came about when we plugged a washing machine into this socket and we started getting shocks from the drum, only tiny but enough to scare the wife.
That is why I tested the socket and discovered no earth.

Cheers
 
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Cirrus

  • Thread Starter Thread Starter
  • #7
have.a.look.in.the.upstairs.sockets.for.a.start.after.testing.8etween.phase.and.earth.for.230v.and.getting.nowhere!!why.dont.you.want.to.lift.the.floor8oards.i'dsay.this.is.the.easiest.option!!and.why.earth.the.8ack8ox.when.more.than.likely.the.screws.will.do.that!!!
It is just good practice to earth metal back boxes. Not necessity but good practice.
 
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TonyM58

  • Thread Starter Thread Starter
  • #8
Exact requirement for earthing back boxes is that if the back box has at least one fixed lug then the additional earth is not required But i agree with cirrus, I always do it as matter of good practice Dazza, is your ring on an RCD?? i am concerned that you are getting shocks, because that implies there is a fault. If you are on an RCD, what happens if you connect the washing machine to a different socket? Because if there is a breakdown between phase or neutral to earth then the RCD should trip. I still think brining a new cable in as a spur is the best option
 
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alan

  • Thread Starter Thread Starter
  • #9
It is possible to run an earth from another socket which is usually a 2.5mm cable.
But the kitchen is one of those special locations, and for peace of mind you should really find out why? Also the sockets Zs must comply with the OSG for the type of fused used.
So anything that is done needs to be tester with a calibrated earth loop tester afterwards.
 
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TonyM58

  • Thread Starter Thread Starter
  • #10
i wouldnt reccomend running an earth from another socket, beacuse the earth fault loop path would be 'odd' in that the fault current would come in on the existing 2.5mm phase (the cable with no earth) and go out a different way on the earth to the new socket. By running a complete new 2.5mm twin and earth you be ensuring it stays 'conventional'

i agree though that further investigation would be desirable, and personally I would want the ZS at the socket, and all of the others while you are at it.

To be honest i would seriuosly consider a full PIR. I know it will cost, but if you are already getting shocks....... what price safety!!!
 
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dazza001

  • Thread Starter Thread Starter
  • #11
cheers for all your help

No the ring is not on an RCD.
We also stopped using that socket straight away and we dont get shocks now we have connected it to the other socket.

I think I will just make a complete new cable run like you say and I will get the loop tested also just for peace of mind.

Cheers guys
 
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TonyM58

  • Thread Starter Thread Starter
  • #12
Dazza,

The reason i asked about the RCD is it sounds like your washing machine has problems.

On the other sockets, the leakage cuyrrent to earth is being 'shunted' away by the earth connectiuon.

If you had an RCD on the ring it would probably trip - FOR A REASON!!!!!

You can replace your MCB (presume you got MCB's and not fuses?) with an RCBO for about 20 quid. that will trip for your safety, and then you can go to Comet and buy your new washing machine - and all you were missing was the earth from a socket!!!!!
 
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Minky

  • Thread Starter Thread Starter
  • #13
Full pir,would be the recommended route,There is a mention of conduit in the intial post,but no mention of what is any readind for earth continuity was done on the conduit??.If earth continuity was achieved on the conduit then by using an earth banjo washer behind the bush,again if installed correctly then it is possible to provide an earth to this socket.Zs is the important test here to ensure that the protective device will operate.Bear in mind that the fault on the washing machine will only get worse.
Since when did kitchens become special locations???
 
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