Neon tester vs dodgy wiring

[Welsh Anorak]

Thanks for all the comments. I always used the abbreviation RCCB - must be getting old! The consumer unit is quite old as well, though, with just four MCBs (one unused).

My partner did suggest replacing the switches with plastic ones, but my point is that the fault wouldn't be cured, and also the metal screws would also be live, so someone coming in from the outside with wet feet (which is beside one affected switch) could easily come into contact with it.
I doubt RF is to blame as it seems odd that only certain plates are affected - and there's still an earth fault present even if that were the case.
I did isolate each switch in case one was leaking, but the earth conductor is carrying the voltage. I suspect post #8 may be close to the truth as I used a digital meter, but as he says there is still an earth fault. Also post#4 - there IS a smell of urine about....
The owners have agreed to get an electrician in to inspect so hopefully all will be revealed. I'll update the post as it is of interest.

[The Philpott]

Please do, you have our attention now..
As you said it's all cross bonded- wonder if it's something as simple as a dead rat in the loft draped over a junction box.

Dave

[hannahs radios]

I think it's good that an electrician is going to have a look at it all 10mA could be dangerous especially if the person is not in good health. Finally I think it probably is switch leakage replacing them with plastic ones would fix it. Finally is the place damp? That might be part of the issue.

[Silicon]

The 'wet' areas such as bathroom and kitchen need to be checked carefully, especially any exposed metalwork.

[Graham G3ZVT]

Glyn, If the room has been wallpapered perhaps damp wallpaper has been slipped behind the switch-plates creating electrical leakage to the un-earthed metalwork?

[crackle]

Originally Posted by teetoon

Glyn, are these switches perhaps some cheap brand that don't comply with UK regs ? Or are they the type with a metal switch ?
I cant see otherwise how a metal faceplate could be leaking 10ma.
If that was really the case then 3 of them would trip an RCD.
You could just change the switches to normal types with no metal front plates.
This would get you out of trouble.

David.

Not sure about that, the fixing screws may still be exposed to touch and live.

The back box and face plate need to be earthed.

Mike

[The Philpott]

If i have read this right, Glyn isolated each switch plate from the earth wire and found that the juice was coming from the earth wire.

Dave

[Herald1360]

Which is well and truly dodgy

Let's see if the sparky finds anything exciting......

[ColinTheAmpMan1]

I came across a similar problem a few years ago when I was re-decorating a bathroom in a flat. I found that a wall-mounted radiant electric heater had full mains voltage on its (supposedly earthed) metal casing. After chasing around pulling up floorboards and the like, I found that some expensive metal double socket outlets were live and that the lighting circuit and one of the ring-mains had their lines connected. I eventually found a nail which had been driven into the wall to hang a picture had 250 V on it. This nail had blown a piece of the earth conductor in the twin-and-earth wiring and had also shorted between the line of the ring-main and that of the lighting circuit. I eventually dug out the wiring that was embedded in the plaster and replaced it. I understood at the time that a previous owner was an electrician and had installed all of the expensive metal double sockets. What a pity he didn't put a blanking-plate on the pattress where I found the melted earth-wire, rather than just wallpapering over it!
Colin.

[ekcopyephilips]

Loose or disconnected neutral on the consumer side of the meter?

[hannahs radios]

Colin.

Many years ago I lived in a bungalow and my dad put a nail in the wall to hang a photo on. Afterwards we found the bath was slightly live, you could get a distinct tingle with one foot in the bath and the other on the cement floor. The fault was really as you described the nail grazed the live wire and was also in contact with the lead sheath. We got a local electrician to sort it out.

[teetoon]

Hi again, Re post 26/27, I had thought he meant the switch plate was leaking when not connected to earth.
Sorry, my mistake. As I said though, it's impossible to know without being there to do some tests and inspection.

When I moved to my current address (no pun intended), I found I got a tingle from the dinning room light fitting whether switched on or off. When I got round to taking it down, there were a collection of choc blocks behind, and where you would expect 4 terminals, L,N,E and switch return, there were in fact five.

Whoever changed the light fitting had connected the mains earth and loop through earth together and then the switch earth and light fitting earth together in a seperate terminal ! I won't go in to the other things I have since discovered, one being a piece of 3 core rubber flex from the fuse box to feed 10 different lights (and it's an old colours piece of flex) 2.5mm used for lighting etc.

It's worrying when you think these sort of things would be checked before a property goes on the market but I've seen many things that would not pass a proper inspection.

One thing to note in Glyn's original post is the existence of rubber cable in the installation. In lighting circuits old enough to have been made in rubber there was quite often no earth at all.

Maybe there is no earth feeding the lighting circuit but later fittings and switches have been wired in twin and earth. Then it's going to be leakage through the capacitance of the cables.

I do hope Glyn comes back with some news.

David.

[winston_1]

Originally Posted by paulsherwin

If it's going to be rented out then the landlord will need to fork out for a proper electrical inspection and remedial work as necessary. Anything else is asking for trouble.

You may think so, but it is not a requirement in England, though it is in Scotland.

[Welsh Anorak]

Or Wales!
I've contacted the owners and they are sending their electrician. Mind you, if he's the one that's done the work I won't be too confident.
Ref post #32 there is one twin and earth from the consumer unit feeding all the lighting. This earth is good and there is good continuity from this and all other parts of the house to exposed metalwork (all X-bonded).
I suspect whoever connected the lower floor just found live and neutral in a lighting junction box and connected the circuit to that. However, I would have thought all the earths would have been connected together somewhere, but that doesn't seem to be the case. Odd!
I've checked for dampness, mails and so on. I'm just going to have a look at an outside light.
I'll keep you posted!

[paulsherwin]

Originally Posted by winston_1

You may think so, but it is not a requirement in England, though it is in Scotland.

It may not be a legal requirement, but the consequences of not doing it can be severe. If somebody dies because of an electrical fault then the landlord will face prosecution. Even if nobody is hurt, the tenant will be gifted a bargaining chip in any landlord/tenant dispute. Local media love 'greedy irresponsible landlord' stories.

[The Philpott]

Ah, outside lights. Seems whether IP44, IP65, sooner or later the water gets in and stays in. Just bought an LED luminaire but protecting it with a metal hood as the cable entry gland faces upwards with the light shining downwards.

Dave

[cheerfulcharlie]

Originally Posted by Welsh Anorak

Hi
Hope this is in the right place!
My partner who is painting and decorating a house called to say she's had a mild shock from a metal switch faceplate. I went along and sure enough my trusty neon screwdriver lit up dimly. It turns out several light switches on the ground floor are between 70 and 200v above true earth.
I'd say the wiring is about 25 years old, but has been 'improved' by these metal switches and sockets. It has an RCCB which works in the good area of the house, and all cross-bonding has been done.
I tried earthing the light switch in question via a milliammeter to a good earth - around 10mA drawn and all was well - except the others were still live!
So I'm in a bit of a dilemma. The work she's doing is for an acquaintance who lives abroad and the house is to be let out in two weeks. I let them know about the shock and they said the electrics had had a clean bill of health 12 months ago. Looking under the bonnet there's the usual enthusiastic DIY approach - faceplates earthed but not the back boxes and the odd bit of rubber cable (no earth). This ties in with the general state of repair of the house.
I can't in all conscience let them rent the house without insisting they get this sorted, but if I was in the position of the electrician I'd be suggesting a rewire which won't go down at all well. I'm not Part P so this is not something I want to get involved with, especially as it'll be a floorboards up job.

Is any leakage permissible? Any ideas or suggestions?

This might sound quite mad but here goes...
(if you have now earthed the backboxes and the symptoms remain then don't bother with the following)

If it's an older property then the backboxes are often cemented into the brickwork, these sometimes corrode at the back obviously due to the reaction of the cement and any moisture in the walls, the backbox thus becomes a capacitor plate with a charge...don't laugh.

PS. electricians often leave these old boxes in because they can be absolute hell to get out..much chiseling and damage to brickwork as well.

[The Philpott]

I can well believe this sort of electrolytic weirdness...would it be DC in this scenario?

Dave

[AC/HL]

Originally Posted by Welsh Anorak

I've contacted the owners and they are sending their electrician.

That's good. I'd just agree, say "let me know how they get on" to show interest, and beat a hasty retreat.

Whatever your opinion of them, they're deemed competent by whoever and will be responsible for any consequences.

[duncanlowe]

Originally Posted by teetoon

I won't go in to the other things I have since discovered, one being a piece of 3 core rubber flex from the fuse box to feed 10 different lights (and it's an old colours piece of flex) 2.5mm used for lighting etc.

In a supposedly re-wired house. 2.5mm twin and earth rubber for a socket. I think it had an earth. Some of the other sockets were wired in 2.5mm PVC twin. No not T&E there was no earth. On some of those but not all a piece of probably 0.5mm green yellow flex had been added, others had nothing. So my (then) girlfriend came home to find her house in darkness and me busy making it safer.

One thing to note in Glyn's original post is the existence of rubber cable in the installation. In lighting circuits old enough to have been made in rubber there was quite often no earth at all.

In my first house the lighting wiring was rubber. Red and black individual cores, single insulated. Up in the loft, strung between ceramic insulators. In various places joined by twisting the ends together. Fuses in both live and neutral presumably from the days of DC being + and -. I lived by a lead lamp for a couple of days until I rewired that circuit! Oh and the kitchen strip light was connected to the + and - with some bell wire.