No Neutral

[mjtefc9]

I had a break in our lighting circuit earth, been like it when we moved in but only became apparent 10 years later when I fitted metal light switches.

The earth was disconnected but picked up 70v due to being in the same cable as the live.

You should not have got a belt from the socket with a good earth, there is something wrong somewhere. Is there any provision for an earth wire to the face plate?.

Yeah it had a fly lead to the box, I'll get the tester and see what happens.

It's a strange one as it only happened once the Neutral broke??

And was fine as soon as I fixed it?

 

[JohnW2]

It's a strange one as it only happened once the Neutral broke?? ... And was fine as soon as I fixed it?

It does sound strange, but there's not really any point in speculating about it. As has been said, it sounds as if something is very wrong (and may well still be very wroing) and needs to be investigated and rectified urgently.

As has also been said, if the faceplate really were effectively earthed then it would be all-but-impossible to get a significant shock by touching it, regardless of anything/everything else.

Kind Regards, John

 

[bernardgreen]

and this was the only fault..

As others are trying to get you to accept. There is a fault that you need to find.

 

[FrodoOne]

You wrote "I got a belt from the (metal) front of the inside socket after it was fixed back and the juice on.. which had me baffled as it all worked perfect. I put my socket tester in the inside socket all ok... outside socket flashed up live earth reverse..

Anyway took the front of (sic) both sockets and the neutral to from the outside socket to the inside had sheared of in the terminal when I'd forced the metal faceplate back.. so all rectified and working great... no more belts!"

If the Neutral had sheared off when the Metal faceplate was forced back, it is possible that
the sheared Neutral was touching the metal faceplate
the metal face plate was not Earthed
there was something plugged into the outside socket outlet which completed a circuit (containing the impedance of the "something") from the Line to the sheared off Neutral.

If you received a "belt" from the inside metal faceplate, across what did you receive the "belt"?
a. Just the fingers of one hand?
b. Between one hand and the other?
c. Between one hand and some other body part?
Because, you cannot receive a "belt" from touching just one thing at any potential - except for an electrostatic discharge, which is quite a different matter.

 

[mjtefc9]

You wrote "I got a belt from the (metal) front of the inside socket after it was fixed back and the juice on.. which had me baffled as it all worked perfect. I put my socket tester in the inside socket all ok... outside socket flashed up live earth reverse..

Anyway took the front of (sic) both sockets and the neutral to from the outside socket to the inside had sheared of in the terminal when I'd forced the metal faceplate back.. so all rectified and working great... no more belts!"

If the Neutral had sheared off when the Metal faceplate was forced back, it is possible that
the sheared Neutral was touching the metal faceplate
the metal face plate was not Earthed
there was something plugged into the outside socket outlet which completed a circuit (containing the impedance of the "something") from the Line to the sheared off Neutral.

If you received a "belt" from the inside metal faceplate, across what did you receive the "belt"?
a. Just the fingers of one hand?
b. Between one hand and the other?
c. Between one hand and some other body part?
Because, you cannot receive a "belt" from touching just one thing at any potential - except for an electrostatic discharge, which is quite a different matter.

Hi Frodo,

I was thinking it may of been a build up of static, I had the battery powered hand held hoover cleaning it all and hoovered the socket face plate as it had dust on it.. I felt a slight tingle when doing this and used my other hand to touch the plate and got the shock.. was it just a build up of static you think?

 

[ericmark]

Can't remember the date, but for a long time sockets used outside needed RCD protection, however as @FrodoOne has said the neutral touching the outer plate could make it live, remember neutral is a live wire, and could have up to 50 volt on it with TT earthing, and I know from bitter experience you can still get a nasty belt before the RCD has had time to trip. However it still should have tripped.

So either the work was non compliant and had no RCD protection, or the RCD did not switch the neutral and the neutral to earth voltage has risen enough to feel it. I don't think any of my neutrals are switched by the RCBO breakers in my consumer unit, so should my TN-C-S supply become faulty and neutral voltage should rise above true earth, there is nothing in my consumer unit that would disconnect the neutral other than the isolator.

However if the neutral is at 50 volt to true earth, so are all the earth wires with a TN-C-S system, and if the neutral is made live by some thing connecting it to neutral like an item plugged in, it would still cause an imbalance and cause the RCD/RBCO to trip if the RCD/RBCO is in the consumer unit, only if the RCD is local i.e. built into the socket, could you still get a shock.

So the big question does a plug in tester actually test the socket well enough?

These testers are quite good really, OK 1.7Ω pass is a bit high, and it will not detects earth - neutral reversal, but they are reasonable enough to ensure all is good, but

this one has no loop test, there is a big difference between the £3 and £40 versions of plug in tester.

I do question the use of cheap testers, do they give the user a false sense of security? The expensive one has it written on the front that it will not detect earth - neutral reversal, nothing on the cheap one. However one would hope earth - neutral reversal would cause the RCD to trip.

So why did the RCD not trip.
1) Not fitted.
2) Local after the fault.
3) Faulty.

 

[mjtefc9]

Can't remember the date, but for a long time sockets used outside needed RCD protection, however as @FrodoOne has said the neutral touching the outer plate could make it live, remember neutral is a live wire, and could have up to 50 volt on it with TT earthing, and I know from bitter experience you can still get a nasty belt before the RCD has had time to trip. However it still should have tripped.

So either the work was non compliant and had no RCD protection, or the RCD did not switch the neutral and the neutral to earth voltage has risen enough to feel it. I don't think any of my neutrals are switched by the RCBO breakers in my consumer unit, so should my TN-C-S supply become faulty and neutral voltage should rise above true earth, there is nothing in my consumer unit that would disconnect the neutral other than the isolator.

However if the neutral is at 50 volt to true earth, so are all the earth wires with a TN-C-S system, and if the neutral is made live by some thing connecting it to neutral like an item plugged in, it would still cause an imbalance and cause the RCD/RBCO to trip if the RCD/RBCO is in the consumer unit, only if the RCD is local i.e. built into the socket, could you still get a shock.

So the big question does a plug in tester actually test the socket well enough?

These testers are quite good really, OK 1.7Ω pass is a bit high, and it will not detects earth - neutral reversal, but they are reasonable enough to ensure all is good, but

this one has no loop test, there is a big difference between the £3 and £40 versions of plug in tester.

I do question the use of cheap testers, do they give the user a false sense of security? The expensive one has it written on the front that it will not detect earth - neutral reversal, nothing on the cheap one. However one would hope earth - neutral reversal would cause the RCD to trip.

So why did the RCD not trip.
1) Not fitted.
2) Local after the fault.
3) Faulty.

Hi Rcd protection on the exterior socket and on the circuit at the board... I used a good socket tester not a cheap one and it's saying all perfect.. I'm begining to think it was a big build up of static

 

[winston1]

So two RCDs in line. Not necessary.

 

[bernardgreen]

I'm begining to think it was a big build up of static

How long did the "shock" last ? Static discharge "shocks" are seldom more than a tenth of a second.

 

[mjtefc9]

So two RCDs in line. Not necessary.

Yes I know.. but the exterior has a build in RCD

 

[mjtefc9]

How long did the "shock" last ? Static discharge "shocks" are seldom more than a tenth of a second.

It was only quick.. but felt more than a normal static shock.. I'll test it all once I get the Multimeter to make sure

 

[ericmark]

So two RCDs in line. Not necessary.

I see no problem with a 30 mA RCD in CU and a 10 mA built into the socket, if something left plugged in and it rains, good chance the 10 mA will trip leaving the 30 mA still powering other items in the house. I have a 10 mA and fitting it is on my to do list.

It was only quick.. but felt more than a normal static shock.. I'll test it all once I get the Multimeter to make sure

Not sure how you would test with a standard multimeter? In the main the voltage is too low for insulation testing, current too low for continuity testing, and the loop test on the plug in tester likely does a better job.

The socket clearly earthed so your body would have needed to build up static, seems unlikely, yes I have seen 1 inch long arcs from a tower crane hook to re-bar both earthed caused by high wind and static, but it is unusual.

So I would want to test the RCD, normally I would not worry, but in view of what you have said, I do wonder if RCD faulty?

 

[JohnW2]

It was only quick.. but felt more than a normal static shock.. I'll test it all once I get the Multimeter to make sure

Well, it's starting to sound as if it might conceivably be that it was just static, but there remain some dangerous possibilities, and you really ought to get an electrician to check it out, since he/she will have means of proper testing which you cannot do.

Kind Regards, John

 

[winston1]

Yes I know.. but the exterior has a build in RCD

So you bought the wrong one then!

 

[mjtefc9]

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