Phase Neutral Reverse Fault on Kitchen socket

[intamixx]

I have a strange problem with some sockets in my kitchen and was wondering whether anyone can shed some light on this problem.

I have a "master" twin socket that has a "slave" single socket.  Both sockets are in the kitchen and on the inside wall of which the exterior side faces the garden.  The single socket was put in about 3 years ago when I had the kitchen refurbished, the twin socket has been there for at least 20 years.  There is an light switch for the external garden light about a metre up (and to the right) from the single socket.  Both plug sockets and light switches are flush "in" the wall, with the plastic face-plates extruding out.

I have a Martindale socket tester and a electric tester screwdriver.

Ok, I have unscrewed the master socket plate from the wall and it is fine and the socket tester states it is wired correctly for both sockets.  If I touch the electric tester screwdriver on its metal back box, it shows no current.  There is a slave 3 core wire that is connected to the earth, neutral, live connectors of this twin socket.  It is going up out of this metal back box into the wall, I believe trunked over the outside kitchen door, and then going into the "slave" single socket.  Of course this is all in the wall so I'm not 100% sure how it gets there.  (I vaguely recall seeing the wiring trunked into the wall when the refurb took place).

If I touch the electric tester screwdriver on the single socket metal back box, it shows a current.  In fact earth, live and neutral on the socket are showing current.  If I use an electric socket tester with the single socket front switch in the off position, the socket tester shows the middle light is on.  If I turn the single socket front switch on, 2 lights on the socket tester turn on, which indicates a phase/neutral reverse fault.

If I disconnect the "slave" cable from the master twin socket, all current from the single socket is gone.  This is how I have left it, in the disconnected state.

Does anyone have any idea what is causing this?  I have attached some pictures of the single socket with the switch on and off, and of the master twin socket.  I have already replaced the master twin socket front plate today, but the same result is still occuring.

Many Thanks.

 

[Andy™]

for a start, you do not have a 'master' or 'slave' socket. either the single socket is wired wrong (cant see that from the angle of your photo) or you have a cable fault

also, as most circuits are on a ring, if it is, then unless the double socket is fed from a fused spur, then the wiring has also been done wrong / bodged in that its a spur wired from a spur

you should also get rid of the death trap of a screwdriver

and plug in testers have their limitations. just becuase its showing L-N reversal doesnt mean that L&N are actually reversed

 

[ProDave]

Sound like "kitchen fitter strikes again"  Spur from a spur and wiired wtong at the socket.

 

[Murdoch]

Best you get a competent spark with  mft to do some tests to determine what is actually going on. Looks like a spur off a spur to me.

 

[Doc Hudson]

The initial problem we have here is both of the "testers" you are using have very limited applications and even less useful application with someone who has limited electrical knowledge. As a general rule neither are satisfactory means of proving any conductor is live or dead. Or identifying what actual voltages or polarity are present on a circuit.  Firstly you need a safe approved method to verify that the test equipment itself is working correctly. You could have a failed neon in you indicator plug or a lose connection between the neon's in your indicator plug etc. You could have a faulty contact on a double pole switch on the socket outlet. The first thing I would want to do is check the polarity along the whole circuit and double check the point Andy mentioned, 'is the circuit wired correctly, ring or radial, no spurs off spurs'. Either way these polarity tests would be done dead, not live with the plug in device you are using. There is no sensible reason to have the socket open as you have whilst the circuit is energised. It can all very easily be checked with the circuit dead before re energising the power once the  fault(s) is/are corrected.  Did you have any electrical certificates for the work done 3 years ago?

Doc H  

 

[steptoe]

At best, you may have a wrongly connected single socket with a SP switch,

But, it needs to be correctly tested asap by someone with some proper test equipment.

 

[intamixx]

Hello,
Thanks for the replies.
I triple checked that the single socket was wired correctly.  Live(brown), neutral(blue), earth (yellow/green).  It looked good to me but no I don't have any pictures of it, will try to get some.

I have tried the tester socket on an alternate good socket which shows the correct leds, so I guess I have a little faith in it.

Unfortunately, I do not have a electrical certificate for the kitchen refurb.
I attach pictures of the consumer unit, which is quite old.  I took these pictures last month.
Just i'm curious as to why the single socket appears inducted and the spur off a spur issue.

Thanks.

 

[Andy™]

could be quite a few things wrong. you also dont appear to have any RCD protection to anything either which would have been a requirement at the time the kitchen was done. probably best to get someone in to check all the electrics

 

[Rob_the_rich]

The martindale "check plug" socket testers that I can find are here  http://instrotech.com/martindale-cp501-p-277.html?gclid=CKjCut_pvs0CFVEo0wodXK0LjQ they are slightly different from yours, but your picture does not show the labels. On the one I linked to, two red lights and no light means "no earth"

the picture in the first post of the double socket shows the two earth wires in separate terminals (with a fly lead to the back box), sometimes the connection between the two terminals can become broken. If the earth wires were all put in the same terminal, the socket test on the single socket might test ok on your martindale.

As said above though, you should not have a socket spurred off another socket. Best to get someone in to check it.

note that the supply earth wire (from the red and black cable) looks to be a bit damaged.

 

[Sharpend]

Following on from RtR, the earth from red black cable appears to have the sheath yellow/green going into the screw terminal, could be that the screw is on sheath and therefore not making connection to the conductor? 

As said a spur from a spur is not good and would need checking, that's if the circuit is not a radial per se? 

 

[Rob_the_rich]

Following on from RtR, the earth from red black cable appears to have the sheath yellow/green going into the screw terminal, could be that the screw is on sheath and therefore not making connection to the conductor? 

As said a spur from a spur is not good and would need checking, that's if the circuit is not a radial per se? 

2x 30A and 2x5A in the CU, so no radial socket circuit I can see

 

[Sharpend]

Didn't check the cu myself but take your point. 

 

[Doc Hudson]

Hello,
Thanks for the replies.
I triple checked that the single socket was wired correctly.  Live(brown), neutral(blue), earth (yellow/green).  It looked good to me  <snip>  Unfortunately, I do not have a electrical certificate for the kitchen refurb.
I attach pictures of the consumer unit, which is quite
Thanks.

You cannot actually prove polarity by just looking at colours, an appropriate continuity test meter is needed. Looking at the photographs and the lack of certificates for work done within the past 5 years would suggest to me that work non complicate with BS7671 may have been carried out. I would want to test and verify the whole circuit (or even whole installation) before assuming anything is safe or compliant with BS7671.

Doc H.