Firstly, I'd like to thank everyone who writes here. I've been doing
my first (and last) renovation over the last three years and the
advice here has been invaluable even though I've hardly had to post
myself.

I wonder if anyone can work out what's going on he

I've just replaced plastic light switches with ones that have metal
faceplates, and I *just* can feel electricity when I brush my fingers
against them lightly. I'm certain it's not static -- I can feel the
50hz cycle.

It only happens on one lighting circuit; on other circuits with the
same new switches you can't feel anything.

Does this mean that the earth on that circuit isn't connected? Or
that it is connected and there's electricity flowing continuously to
earth due to a fault, a little of which diverts through me when I
touch the switches? Should I ignore it or try to fix? (The case of
my new laptop feels the same sometimes and the user's manual says it's
normal.)

Any advice appreciated as always.

Max Christian wrote:

I've just replaced plastic light switches with ones that have metal
faceplates, and I *just* can feel electricity when I brush my fingers
against them lightly. I'm certain it's not static -- I can feel the
50hz cycle.

It only happens on one lighting circuit; on other circuits with the
same new switches you can't feel anything.

Likeliest cause is that the earth connector isn't connected to earth
somewhere further back than the switch, and that the 50Hz you can detect
is capacitively coupled into the free-floating earth conductor which is
correctly connected to the switch faceplate. You can check this out
if you have a multimeter - you should find that the resistance between
the faceplate and something-else-which-has-a-good-earth (e.g.: socket
screw, socket earth pin, outer case of a plugged-in non-double-insulated
metal appliance, etc.) is Huge, while the resistance from the faceplates
of the other, non-tingling faceplates to the same point is Negligible
(probably down at 0 ohms unless your meter has an accurate "low ohms"
range). Turn off the power to the lighting circuit while you do this -
less because of the risk of shock (you've shown the available current
at the suspect faceplate is not currently (ha) dangerous), but becuase
it'll louse up your resistance measurement.

But it *is* worth tracking down where the earth connection's missing,
since without an effective earth at your metal faceplate you (and those
who share the house) are at risk in the event of a "hard" fault where
the live directly comes into contact with the faceplate; at that point
what you want to happen is for a brief flash behind the faceplate and
the MCB/fuse for the lighting circuit to trip, EEBADS-style; *not* for
the faceplate to stay live, now with plenty of heart-stopping current
available, to give a nasty (or worse) belt to the victim.

Your previous installation - with plastic faceplates - masked the fault
I'm guessing you have; tens of years ago it wasn't even a requirement
for lighting circuits to have an earth-continuity conductor. Until you
fix the underlying fault (which you should do ASAP), replacing the
metal-faced switch with the previous plastic one is a Good Move - but is
no substitute for the proper fix, mind you...

(While your laptop might give you a similar weak tingle, we Presume it's
a double-insulated/Class-II design where any such current is restricted;
while the tingle you say you're getting suggests the absence of an
effective earth in an arrangement where such an earth *is* a
requirement.)

HTH - Stefek

In message , Max
Christian writes
Firstly, I'd like to thank everyone who writes here. I've been doing
my first (and last) renovation over the last three years and the
advice here has been invaluable even though I've hardly had to post
myself.

I wonder if anyone can work out what's going on he

I've just replaced plastic light switches with ones that have metal
faceplates, and I *just* can feel electricity when I brush my fingers
against them lightly. I'm certain it's not static -- I can feel the
50hz cycle.

It only happens on one lighting circuit; on other circuits with the
same new switches you can't feel anything.

Does this mean that the earth on that circuit isn't connected? Or
that it is connected and there's electricity flowing continuously to
earth due to a fault, a little of which diverts through me when I
touch the switches? Should I ignore it or try to fix? (The case of
my new laptop feels the same sometimes and the user's manual says it's
normal.)

Any advice appreciated as always.

Hmm, I'd wondered about posting a similar question, I've also replaced
some plastic face plates with metal ones and wondered what to do with
the earth cable - as it's currently connected to the original *plastic*
back plate. I can't feel any electricity, so I've left it as is now,
should I move the earth to the face plate - or will it make no
difference as it's only bolted to plastic anyway?

--
Mike Buckley
RD350LC2
http://www.toastyhamster.freeserve.co.uk
BONY#38

"mike. buckley" wrote in message
k...
In message , Max
Christian writes
Firstly, I'd like to thank everyone who writes here. I've been doing
my first (and last) renovation over the last three years and the
advice here has been invaluable even though I've hardly had to post
myself.

I wonder if anyone can work out what's going on he

I've just replaced plastic light switches with ones that have metal
faceplates, and I *just* can feel electricity when I brush my fingers
against them lightly. I'm certain it's not static -- I can feel the
50hz cycle.

It only happens on one lighting circuit; on other circuits with the
same new switches you can't feel anything.

Does this mean that the earth on that circuit isn't connected? Or
that it is connected and there's electricity flowing continuously to
earth due to a fault, a little of which diverts through me when I
touch the switches? Should I ignore it or try to fix? (The case of
my new laptop feels the same sometimes and the user's manual says it's
normal.)

Any advice appreciated as always.

Hmm, I'd wondered about posting a similar question, I've also replaced
some plastic face plates with metal ones and wondered what to do with the
earth cable - as it's currently connected to the original *plastic* back
plate. I can't feel any electricity, so I've left it as is now, should I
move the earth to the face plate - or will it make no difference as it's
only bolted to plastic anyway?


The face plate should be earthed, the connector in the box is there to let
you have an easy way to earth the face plate with a short bit of wire.

"mrcheerful ." wrote in message
.. .


Hmm, I'd wondered about posting a similar question, I've also replaced
some plastic face plates with metal ones and wondered what to do with
the
earth cable - as it's currently connected to the original *plastic* back
plate. I can't feel any electricity, so I've left it as is now, should I
move the earth to the face plate - or will it make no difference as it's
only bolted to plastic anyway?


The face plate should be earthed, the connector in the box is there to let
you have an easy way to earth the face plate with a short bit of wire.

If it is a metal box, I thought it was there to earth the metal box. I'm
sure most of us don't turn off the ring to loosen face plates for
decorating.
Mmm, stripping knifes touching the metal box.

--
Mike W

VisionSet wrote:


The face plate should be earthed, the connector in the box is there to let
you have an easy way to earth the face plate with a short bit of wire.


If it is a metal box, I thought it was there to earth the metal box.

We've had this out on the group a few times; the consensus, which I
share, is that it's (marginally) preferable to run the incoming cable(s)
to the earth terminal on the Accessory - if it has one - e.g. the
socket, fused-connection-unit, whatever - so that there's one fewer
connection to come adrift on the way to the "important" place, which is
whatever the socket/FCU/whatever feeds. A tail to the backbox is then a
better-than-relying-on-the-mounting-screws way to earth the backbox, and
earths the mounting screws for those rare designs where there's an
earthing terminal on the accessory which doesn't itself provide
continuity with the mounting screw surrounds.

For light-switches, things can be different - plastick plateswitches
don't have an earthing terminal, so parking the earth wires in the earth
terminal (usually) provided in the backbox is a sensible way to keep
it/them secure, and - if there are multiple cables, as there will be in
some wiring setups where all the joining's done at the switch positions
rather than in junction boxes and/or loop-in roses - does a "real"
electrical-continuity job. Metal-faced switches generally have an
earthing terminal - it's not simple to design them as
double-insulated/Class-II, as the mounting screws will earth the
faceplate when used with a metal backbox.

Should I move the earth to the face plate?

I've always found that the earth moved for me.

(I'll get my coat)

In message , Stefek Zaba
writes
VisionSet wrote:


The face plate should be earthed, the connector in the box is there to let
you have an easy way to earth the face plate with a short bit of wire.
If it is a metal box, I thought it was there to earth the metal
box.

We've had this out on the group a few times;
snip

Ok - what would you do if there was no earth cable in the wiring and you
wanted to fit a metal face plate to a plastic backing box? The plastic
box does actually have an earth terminal in it - would you use a short
piece of wire from the backing plate to the plastic box (why?)?

--
Mike Buckley
RD350LC2
http://www.toastyhamster.freeserve.co.uk
BONY#38

Ok - what would you do if there was no earth cable in the wiring and you
wanted to fit a metal face plate to a plastic backing box? The plastic box
does actually have an earth terminal in it - would you use a short piece
of wire from the backing plate to the plastic box (why?)?

You run a seperate earth conductor or you don't use the metal faced switch
plate, simple. Or of course you ignore all safety aspects, in which case
you likely wont be asking advice anyway.

Dave

--

Some people use windows, others have a life.

In message , Dave Stanton
writes

Ok - what would you do if there was no earth cable in the wiring and you
wanted to fit a metal face plate to a plastic backing box? The plastic box
does actually have an earth terminal in it - would you use a short piece
of wire from the backing plate to the plastic box (why?)?

You run a seperate earth conductor or you don't use the metal faced switch
plate, simple. Or of course you ignore all safety aspects, in which case
you likely wont be asking advice anyway.

Dave

How could I run a seperate earth conductor?

--
Mike Buckley
RD350LC2
http://www.toastyhamster.freeserve.co.uk
BONY#38

You run a seperate earth conductor or you don't use the metal faced
switch plate, simple. Or of course you ignore all safety aspects, in
which case you likely wont be asking advice anyway.

Dave

How could I run a seperate earth conductor?

Well as I don't know your layout I cant say exactly, but you should be
able to pick up the earth conductor somewhere and join a single to it. The
actual physical running is another matter and could involve a lot of extra
work, ie lifting floorboards, chasing out etc. You might if you were lucky
be able to feed a single conductor down the existing channeling. Very much
a suck it and see operation. Done it a few times and it can be a pain in
the a***. Costs the customer a lot of extra money!. One reason never to
cut off earth conductors, people do because they think they wont be needed
at a certain point, then again people are stupid.

Dave

--

Some people use windows, others have a life.

In message , mike.
buckley writes
In message , Dave Stanton
writes

Ok - what would you do if there was no earth cable in the wiring and you
wanted to fit a metal face plate to a plastic backing box? The plastic box
does actually have an earth terminal in it - would you use a short piece
of wire from the backing plate to the plastic box (why?)?

You run a seperate earth conductor or you don't use the metal faced switch
plate, simple. Or of course you ignore all safety aspects, in which case
you likely wont be asking advice anyway.

Dave

How could I run a seperate earth conductor?


Actually - none of the downstairs light switches have a cable for earth
(upstairs do). I guess I'm going to have to run a cable from the
switch/faceplate to a suitable earthing point - for instance central
heating copper pipe?

--
Mike Buckley
RD350LC2
http://www.toastyhamster.freeserve.co.uk
BONY#38

In message , Dave Stanton
writes

You run a seperate earth conductor or you don't use the metal faced
switch plate, simple. Or of course you ignore all safety aspects, in
which case you likely wont be asking advice anyway.

Dave

How could I run a seperate earth conductor?

Well as I don't know your layout I cant say exactly, but you should be
able to pick up the earth conductor somewhere and join a single to it. The
actual physical running is another matter and could involve a lot of extra
work, ie lifting floorboards, chasing out etc. You might if you were lucky
be able to feed a single conductor down the existing channeling. Very much
a suck it and see operation. Done it a few times and it can be a pain in
the a***. Costs the customer a lot of extra money!. One reason never to
cut off earth conductors, people do because they think they wont be needed
at a certain point, then again people are stupid.

Dave


Great advice here thanks - there is a nearby socket I can use for this,
although it's going to be a major pain in the arse for the other
downstairs rooms. I guess it means a bit of plastering :-(

--
Mike Buckley
RD350LC2
http://www.toastyhamster.freeserve.co.uk
BONY#38

Actually - none of the downstairs light switches have a cable for earth
(upstairs do). I guess I'm going to have to run a cable from the
switch/faceplate to a suitable earthing point - for instance central
heating copper pipe?

NO NO, NOT A SUITABLE POINT. You need to take it to a earth point in a
socket, junction box etc, but do make sure that the connection is part of
the earth circuit.

Dave

--

Some people use windows, others have a life.

In message , Dave Stanton
writes

Actually - none of the downstairs light switches have a cable for earth
(upstairs do). I guess I'm going to have to run a cable from the
switch/faceplate to a suitable earthing point - for instance central
heating copper pipe?

NO NO, NOT A SUITABLE POINT. You need to take it to a earth point in a
socket, junction box etc, but do make sure that the connection is part of
the earth circuit.

Dave


Dave, thanks very much, one last question...

As this is a new cable run and is just being used for earth, could I use
a single core cable (sheathed with green/yellow), or would you advise
using one of the cables from a twin core to get the benefit of the extra
cable protection? I don't want to bodge this, the house has had enough
bodges on it so far by previous owners without me adding to them. I
think the cable run will be easy enough - a channel down by the door
frame and then it can be tucked under the skirting round to the socket.

--
Mike Buckley
RD350LC2
http://www.toastyhamster.freeserve.co.uk
BONY#38

In article ,
mike. buckley wrote:
Great advice here thanks - there is a nearby socket I can use for this,
although it's going to be a major pain in the arse for the other
downstairs rooms. I guess it means a bit of plastering :-(

If you're going to have to re-plaster, do the job properly and make sure
there's an earth throughout the lighting circuit in the normal way. If the
earth's been cut or left off, gawd knows what other bodges you'll find. If
it never was present, the wiring is old.

--
*I don't know what your problem is, but I'll bet it's hard to pronounce

Dave Plowman London SW
To e-mail, change noise into sound.

In message , "Dave Plowman (News)"
writes
In article ,
mike. buckley wrote:
Great advice here thanks - there is a nearby socket I can use for this,
although it's going to be a major pain in the arse for the other
downstairs rooms. I guess it means a bit of plastering :-(

If you're going to have to re-plaster, do the job properly and make sure
there's an earth throughout the lighting circuit in the normal way. If the
earth's been cut or left off, gawd knows what other bodges you'll find. If
it never was present, the wiring is old.


I suspect this house has never been re-wired since it was built - late
1930s. The wiring is just 2 core in a grey round sheath, all the back
boxes are nasty grey plastic. Possibly upstairs has been re-wired with 3
core, but there's no obvious sign of re-plastering anywhere except the
hall, everywhere else is the original lathe and plaster.

--
Mike Buckley
RD350LC2
http://www.toastyhamster.freeserve.co.uk
BONY#38

As this is a new cable run and is just being used for earth, could I use a
single core cable (sheathed with green/yellow), or would you advise using
one of the cables from a twin core to get the benefit of the extra cable
protection? I don't want to bodge this, the house has had enough bodges on
it so far by previous owners without me adding to them. I think the cable
run will be easy enough - a channel down by the door frame and then it can
be tucked under the skirting round to the socket.

Yes, green/yellow earth conductor 1.0mm or 1.5mm will be ok.

Dave
--

Some people use windows, others have a life.

If you're going to have to re-plaster, do the job properly and make sure
there's an earth throughout the lighting circuit in the normal way. If the
earth's been cut or left off, gawd knows what other bodges you'll find. If
it never was present, the wiring is old.

Good point Dave

Dave

--

Some people use windows, others have a life.

In article ,
mike. buckley wrote:
Possibly upstairs has been re-wired with 3
core, but there's no obvious sign of re-plastering anywhere except the
hall, everywhere else is the original lathe and plaster.

With lath and plaster you can do the majority of the runs without needing
to re-plaster. Just the bits where you have to cross the noggins.

--
*If at first you don't succeed, destroy all evidence that you tried *

Dave Plowman London SW
To e-mail, change noise into sound.

In message , "Dave Plowman (News)"
writes
In article ,
mike. buckley wrote:
Possibly upstairs has been re-wired with 3
core, but there's no obvious sign of re-plastering anywhere except the
hall, everywhere else is the original lathe and plaster.

With lath and plaster you can do the majority of the runs without needing
to re-plaster. Just the bits where you have to cross the noggins.


Excuse my french - but what's a noggin? I'm going to run a single 1.0mm
earth wire to a socket down the edge of a door frame, all sheathed by
graan/yellow. Bit of a pain in the arse, but nothing compared to the
grief from the girlf of having a plastic socket in a house full of
stainless ones....

--
Mike Buckley
RD350LC2
http://www.toastyhamster.freeserve.co.uk
BONY#38

In article ,
mike. buckley wrote:
With lath and plaster you can do the majority of the runs without
needing to re-plaster. Just the bits where you have to cross the
noggins.


Excuse my french - but what's a noggin? I'm going to run a single 1.0mm
earth wire to a socket down the edge of a door frame, all sheathed by
graan/yellow. Bit of a pain in the arse, but nothing compared to the
grief from the girlf of having a plastic socket in a house full of
stainless ones....

A lath and plaster wall is hollow. It's constructed out of vertical studs.
But at perhaps two places there will be horizontal 'noggins' to add
strength and prevent twisting. These also stop you just dropping a cable
from top to bottom. But you can channel out over the noggin and bring the
cable round over it, then make good.

--
*It is easier to get older than it is to get wiser.

Dave Plowman London SW
To e-mail, change noise into sound.

As this is a new cable run and is just being used for earth, could I use
a single core cable (sheathed with green/yellow), or would you advise
using one of the cables from a twin core to get the benefit of the extra
cable protection? I don't want to bodge this, the house has had enough
bodges on it so far by previous owners without me adding to them. I
think the cable run will be easy enough - a channel down by the door
frame and then it can be tucked under the skirting round to the socket.

Running an extra cable off to some other circuit to pick up an earth is
itself a bit of a bodge (not a terrible one, but definitely not best
practice); the "fully right" thing to do is to rewire your downstairs
lighting circuit with new cable which includes the earth conductor.
You'll be able to reuse most or all of the existing cable route, but if
the old stuff is plastered in you'll get plenty of practice in applying
one-coat patching plaster!

Unearthed lighting circuits wnet out-of-regs at least 30 years ago,
which suggests your downstairs circuit cable is coming to the end of
its useful. It's not that likely to be the original 30s you mentioned
in a previous post - back then it would've been rubber-sheathed, and
you'd find that the insulation would be crumbling off it the moment
you unscrewed the old fittings and moved the cable around a bit. (If
that *is* happening, BTW, you need to rewire *urgently*, as the risk
of sparks and in the worst case fire is well above neglible...)

HTH - Stefek

"mike. buckley" wrote in message . uk...
In message , "Dave Plowman (News)"
writes

Great advice here thanks - there is a nearby socket I can use for this,
although it's going to be a major pain in the arse for the other
downstairs rooms. I guess it means a bit of plastering :-(

Borrowing an earth connection from the socket circuit is against regs,
as its possible someone could one day disconnect the socket cct, but
leave the lights powered up. However, it will clearly greatly increase
the safety of your dodgy setup.


If you're going to have to re-plaster, do the job properly and make sure
there's an earth throughout the lighting circuit in the normal way. If the
earth's been cut or left off, gawd knows what other bodges you'll find. If
it never was present, the wiring is old.


I suspect this house has never been re-wired since it was built - late
1930s. The wiring is just 2 core in a grey round sheath, all the back
boxes are nasty grey plastic. Possibly upstairs has been re-wired with 3
core, but there's no obvious sign of re-plastering anywhere except the
hall, everywhere else is the original lathe and plaster.

Uhoh. If its really that old, or even 40s or 50s, dangers are bound to
be lurking. The number 2 rule with really old wiring is dont move it,
not even slightly. A quarter inch of movement is enough to cause a
short or fire if the rubber's perished - and it normally is.

The number 1 rule? Disconnect it and rewire. 1930s wiring is anything
but safe: in fact 30s wiring in the condition it will be in today
would have been condemned even back in the 30s. I dont know when
lighting had to have earths, but 2 core lighting is very old, and
probably well past its reasonably safe by date.

I _really_ wouldnt want metal light switches on a dodgy setup like
that. Even when earthed, the level of shock protection is liable to be
real poor, and the odds of earthed things going live quite high. Why?
High earth impedances, wire fuses, no RCD, no crossbonding, no
earthing on parts of the install, heavily corroded wiring, high
probability of shorts, high leakage... no thank you. get it fixed.


Regards, NT

In message , Stefek Zaba
writes
As this is a new cable run and is just being used for earth, could I
use a single core cable (sheathed with green/yellow), or would you
advise using one of the cables from a twin core to get the benefit of
the extra cable protection? I don't want to bodge this, the house has
had enough bodges on it so far by previous owners without me adding
to them. I think the cable run will be easy enough - a channel down
by the door frame and then it can be tucked under the skirting round
to the socket.

Running an extra cable off to some other circuit to pick up an earth is
itself a bit of a bodge (not a terrible one, but definitely not best
practice);
snip

I've had a look round the rest of the downstairs cabling. Only the
kitchen and the lounge have no earth, so it looks like the rest of it
has been redone at some point. The lounge wiring looks in pretty good
condition, it does look like a grey rubber sheath on the wiring but its
not flaking at all. I've already got the new earth cable hidden behind
the door frame, but I haven't yet cabled it to the socket (going to make
it flush fit later this week).

--
Mike Buckley
RD350LC2
http://www.toastyhamster.freeserve.co.uk
BONY#38

In article ,
mike. buckley wrote:
The lounge wiring looks in pretty good
condition, it does look like a grey rubber sheath on the wiring but its
not flaking at all.

If it's grey, it's probably PVC. Rubber outer was normally black. But is
there an earth conductor inside? Might well have been cut off at the ends.

The sure way would be to measure the size of the conductor with a
micrometer or similar. Rubber cable if single strand will be 0.044 in or
if stranded will have three 0.029. These sizes also existed with early PVC
cables. Post '70 or so cables will be single strand metric.

--
*I took an IQ test and the results were negative.

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
mike. buckley wrote:
The lounge wiring looks in pretty good
condition, it does look like a grey rubber sheath on the wiring but its
not flaking at all.


IMHO OP should determine if its grey pvc or grey lead, they can look
similar. A superficial metal scrape will reveal either bright metallic
lead or lighter grey pvc.

NT

In message , N. Thornton
writes
In article ,
mike. buckley wrote:
The lounge wiring looks in pretty good
condition, it does look like a grey rubber sheath on the wiring but its
not flaking at all.


IMHO OP should determine if its grey pvc or grey lead, they can look
similar. A superficial metal scrape will reveal either bright metallic
lead or lighter grey pvc.

NT

It's lighter grey pvc, and there's definitely no third core earth wire.

--
Mike Buckley
RD350LC2
http://www.toastyhamster.freeserve.co.uk
BONY#38