Mild tingling sensation from metal light switch?

[Ivan Dobsky]

Is it normal to feel a very mild buzzing/tingling sensation from a metal
light switch plate? You can only feel it if you gently run a finger at right
angles to the 'grain' on the brushed metal surface. There's only one in the
house, so I can't compare it to any others. It all looks fine inside the
box.

[Andy Burns]

Fine includes the backbox having an earth connection, presumably? Does
the switch have a double insulated "square within a square" logo on it?

[Martin Brown]

No. It suggests that the metal isn't earthed and a leakage path to live.

I expect it will also light one of those neon screwdrivers we are not
supposed to use any more due to strange elfin safety rulz.

--
Regards,
Martin Brown

[Tim Watts]

Barring some really weird problem, my conclusion is:



Your earthing is buggered to that switch.

Get it checked IMMEDIATELY by someone competant...

It's not "normal" - it's presumed dangerous.


--
Tim Watts Personal Blog: http://squiddy.blog.dionic.net/

http://www.sensorly.com/ Crowd mapping of 2G/3G/4G mobile signal coverage

Reading this on the web? See:
http://wiki.diyfaq.org.uk/index.php?title=Usenet

[Ivan Dobsky]

"Andy Burns" <usenet....@adslpipe.co.uk> wrote in message
news:O56dndrb_phwwDHM...@brightview.co.uk...

Yes, the box is earthed. I'll have to check for the logo later.

I forgot to mention that there are several metal mains outlets that do not
feel like this, so I have to assume something's wrong.

[Ivan Dobsky]

"Ivan Dobsky" <iv...@dobsky.com> wrote in message
news:feudnTs2Q_gzwTHM...@eclipse.net.uk...

Thanks, everyone. I'll get it checked.

Previous owner said the kitchen (including electrics) was fitted by Moben,
and seemed quite proud of it. A few things I've seen in there don't impress
me very much.

[Ivan Dobsky]

"Martin Brown" <|||newspam|||@nezumi.demon.co.uk> wrote in message
news:V7Zqt.28614$xl6....@newsfe15.iad...

The only one I have has a battery in it (so you can use it to test fuses and
things), and seems to light up whatever you touch.

> --
> Regards,
> Martin Brown

[Dave Plowman (News)]

In article <sI-dnVAvZLQi_THM...@eclipse.net.uk>,

Ivan Dobsky <iv...@dobsky.com> wrote:
> > Fine includes the backbox having an earth connection, presumably? Does
> > the switch have a double insulated "square within a square" logo on
> > it?
> >

> Yes, the box is earthed. I'll have to check for the logo later.

Just because it has an earth wire doesn't mean it's actually earthed.
Could be a break in the wiring elsewhere. You need to check the earth at
that point - or have it checked professionally.

> I forgot to mention that there are several metal mains outlets that do
> not feel like this, so I have to assume something's wrong.

Do you mean sockets? At one time it wasn't required to have an earth
circuit connected on lighting circuits - even although TW&E cable was
used. 3 pin sockets have always required an earth connection.

--
*Puritanism: The haunting fear that someone, somewhere may be happy.

Dave Plowman da...@davenoise.co.uk London SW
To e-mail, change noise into sound.

[Clive George]

On 03/06/2013 10:06, Ivan Dobsky wrote:

Given you say you only feel it when stroking one way, might be worth
checking if you still feel it with the relevant circuit switched off.
(doing it blind, ie get somebody else to switch but not tell you which
way, means you also eliminate potential bias, but I appreciate that may
be getting harder :-) ). If so, it's something other than the leccy and
not a problem, and you've saved yourself some grief.

[Ivan Dobsky]

"Dave Plowman (News)" <da...@davenoise.co.uk> wrote in message
news:5355f28...@davenoise.co.uk...

> In article <sI-dnVAvZLQi_THM...@eclipse.net.uk>,
> Ivan Dobsky <iv...@dobsky.com> wrote:
>> > Fine includes the backbox having an earth connection, presumably? Does
>> > the switch have a double insulated "square within a square" logo on
>> > it?
>> >
>
>> Yes, the box is earthed. I'll have to check for the logo later.
>
> Just because it has an earth wire doesn't mean it's actually earthed.
> Could be a break in the wiring elsewhere. You need to check the earth at
> that point - or have it checked professionally.
>
>> I forgot to mention that there are several metal mains outlets that do
>> not feel like this, so I have to assume something's wrong.
>
> Do you mean sockets? At one time it wasn't required to have an earth
> circuit connected on lighting circuits - even although TW&E cable was
> used. 3 pin sockets have always required an earth connection.

Yes, I mean sockets.

[Tim Watts]

There may be a causal link between "Moben" and "not impressed"...

[Ivan Dobsky]

"Tim Watts" <tw+u...@dionic.net> wrote in message
news:558u7a-...@squidward.local.dionic.net...

> On Monday 03 June 2013 10:28 Ivan Dobsky wrote in uk.d-i-y:
>
>>
>> "Ivan Dobsky" <iv...@dobsky.com> wrote in message
>> news:feudnTs2Q_gzwTHM...@eclipse.net.uk...
>>> Is it normal to feel a very mild buzzing/tingling sensation from a metal
>>> light switch plate? You can only feel it if you gently run a finger at
>>> right angles to the 'grain' on the brushed metal surface. There's only
>>> one in the house, so I can't compare it to any others. It all looks fine
>>> inside the box.
>>
>> Thanks, everyone. I'll get it checked.
>>
>> Previous owner said the kitchen (including electrics) was fitted by
>> Moben,
>> and seemed quite proud of it. A few things I've seen in there don't
>> impress me very much.
>
> There may be a causal link between "Moben" and "not impressed"...

There just might be. The most annoying thing is the waste pipe under the
sink that goes upwards an inch or so before it goes outside. The hot/cold
plumbing under the sink seems unnecessarily complicated, too. It's like a
pile of trombones under there. There's a twin socket right under this lot,
too. I'm sure there should be something covering them, in case there's a
leak under the sink.

[Bob Minchin]

Agreed.
The op also said it was buzzing and that could be a suppression choke
vibrating at 50/100 Hz which would be no problem at all.

[Bill Wright]

Ivan Dobsky wrote:
> Is it normal to feel a very mild buzzing/tingling sensation from a metal
> light switch plate? You can only feel it if you gently run a finger at right
> angles to the 'grain' on the brushed metal surface.

That will be a tiny bit of leakage from the mains. All satellite boxes
do it as long as they aren't earthed via the dish or the TV connection.
You rub your finger along the case and you feel a tingle; press hard and
you feel nothing. The switch must be lacking an earth connection.

Bill

[Grimly Curmudgeon]

On Mon, 3 Jun 2013 10:28:53 +0100, "Ivan Dobsky" <iv...@dobsky.com>
wrote:

>Previous owner said the kitchen (including electrics) was fitted by Moben,
>and seemed quite proud of it. A few things I've seen in there don't impress
>me very much.

Kitchen fitters make shit electricians.
One bloody idiot was quite happy to have the dishwasher and w/machine
both plugged into a 4-way trailing outlet left under the kickboard.
Said 4-way was hard-wired into the back of a double socket. Ffs.

[Ivan Dobsky]

"Bob Minchin" <bob.minc...@YOURHATntlworld.com> wrote in message
news:kohvtt$q2i$1...@dont-email.me...

I probably should have used a word other than 'buzzing', but it is not a
sound, just the way it feels, and I can't think of a better word. It's not
really a tingle, either. You can only feel it when you very lightly brush
your fingertips across the plate, and it seems to vibrate. You can't feel it
when you just touch it. It's quite hard to describe. If you've ever walked
under overhead cables with an umbrella, and gently rubbed the stem, you can
feel something similar.

[Ivan Dobsky]

"Grimly Curmudgeon" <gri...@gmail.com> wrote in message
news:db2pq852fqp0q9ffk...@4ax.com...

I can believe it. It all looks very nice from the front, as it were; but
behind and underneath, there are a few things I wouldn't have done.

[John Williamson]

I get the same on the laptops, which both have two core mains leads.
It's a few microamps of leakage current, and in your case, it means that
the faceplate isn't earthed, and there's a very high resistance leakage
path from the live inside the box to the faceplate. Worth investigating
further in case something goes more seriously wrong.

--
Tciao for Now!

John.

[GB]

Why would the OP feel it if he brushes his finger one way and not the
other?

I'm voting for it being something to do with the grain, but I'd check
out the earthing too.

[Ivan Dobsky]

"Bill Wright" <bi...@invalid.com> wrote in message
news:koi1g9$2in$1...@speranza.aioe.org...

Yes, press hard (or just touch) and you don't feel it. There is an earth
connection in there (first thing I looked for), but I've not checked that
it's actually connected to anything once the wire disappears into the hole.

[Ivan Dobsky]

"GB" <NOTso...@microsoft.com> wrote in message
news:51ac8bfe$0$1127$5b6a...@news.zen.co.uk...

I wouldn't be surprised if it was just the grain, after all. Perhaps it's
just the right texture to set off a vibration effect in the skin. I've no
idea how you can verify that. But yes, I'll try to check the earth too.

[Clive George]

I've told you one way - try it with the leccy off.

[Ivan Dobsky]

"Clive George" <cl...@xxxx-x.fsnet.co.uk> wrote in message
news:Vb2dnVqjJt-nDzHM...@brightview.co.uk...

Doh! Of course. Thanks.

[Brian Gaff]

Is the box and screws and front panel earthed. If yes, then its not working!
This electrostatic effect is often felt on brushed ally fronts of hi fis
etc, but if the earth is connected to it, you should not feel it at all.
Brian

--
From the Sofa of Brian Gaff Reply address is active

"Ivan Dobsky" <iv...@dobsky.com> wrote in message
news:feudnTs2Q_gzwTHM...@eclipse.net.uk...

[Brian Gaff]

Yup we call that the Shania Twains..
Seriously though, if the metal bit is not connected to anything, it will
probably always be that way, just like a brushed ally knob on an old dimmer
we had was as it was on a plastic spindle.

Brian

--
From the Sofa of Brian Gaff Reply address is active

"Ivan Dobsky" <iv...@dobsky.com> wrote in message

news:dq-dndu1I-hL_DHM...@eclipse.net.uk...

[Brian Gaff]

However the long runs of water pipe seems to be normal and possibly to help
with the flexing on g the modern thin mountings for the taps so they do not
break a joint!

Brian

--
From the Sofa of Brian Gaff Reply address is active

"Grimly Curmudgeon" <gri...@gmail.com> wrote in message
news:db2pq852fqp0q9ffk...@4ax.com...

[Brian Gaff]

Yes I get that with my long white cane on the metal crook. I think there is
a theory that we are sensitive to electrostatic changes. This is one theory
on how divining works of course.

Brian

--
From the Sofa of Brian Gaff Reply address is active

"Ivan Dobsky" <iv...@dobsky.com> wrote in message

news:PoWdnblMio7WFzHM...@eclipse.net.uk...

[Brian Gaff]

Well, suggestion.
Undo one of the screws, get a bit of stiff bare wire, and bend it so when
you do the screw up it presses against the tingly surface, now test for
tingle. if the tingle is there, then your earth lead is bust, if not then
the metal you are touching is just stuck on and there is no connection to
the earthed box. Probably quite safe, but if it worries you devise a cunning
plan to connect it from behind to the box.

Brian

--
From the Sofa of Brian Gaff Reply address is active
"Ivan Dobsky" <iv...@dobsky.com> wrote in message

news:-qSdnUE8Z-GxETHM...@eclipse.net.uk...

[Ivan Dobsky]

"Brian Gaff" <Bri...@blueyonder.co.uk> wrote in message
news:koi93t$itu$1...@dont-email.me...

> However the long runs of water pipe seems to be normal and possibly to
> help with the flexing on g the modern thin mountings for the taps so they
> do not break a joint!

Maybe, but the problem is not so much that they are long, but rather
'jumbled up'. I'd have put two long straight pipes along the wall (hot and
cold), and made connections behind the appliances where necessary. Here,
they all meet under the sink with lots of short curved bits joined together.
I can imagine that some of them are under a worrying amount of mechanical
stress. Perhaps I should learn to worry a bit less :)

[Ivan Dobsky]

"Brian Gaff" <Bri...@blueyonder.co.uk> wrote in message

news:koi8j1$fra$1...@dont-email.me...

> Is the box and screws and front panel earthed. If yes, then its not
> working!
> This electrostatic effect is often felt on brushed ally fronts of hi fis
> etc, but if the earth is connected to it, you should not feel it at all.
> Brian

I've just had the multimeter out. I don't think the front plate is earthed.
Measuring the resistance between it and other plates and screws in the
vicinity also shows open circuit, whereas a measurement between any two
other things shows that they are all connected. Even though this switch's
metal box has an earth wire connected, and there is also one to the switch
plate, I'll have to assume that the connection is lost somewhere in the wall
or ceiling.

My guess is that the strange tingling sensation is this electrostatic effect
that BG mentions; or electricity induced in the faceplate due to the
proximity of the mains cable. Or is that what 'electrostatic effect' means?

[Ivan Dobsky]

"Brian Gaff" <Bri...@blueyonder.co.uk> wrote in message

news:koi9k5$lub$1...@dont-email.me...

> Well, suggestion.
> Undo one of the screws, get a bit of stiff bare wire, and bend it so when
> you do the screw up it presses against the tingly surface, now test for
> tingle. if the tingle is there, then your earth lead is bust, if not then
> the metal you are touching is just stuck on and there is no connection to
> the earthed box. Probably quite safe, but if it worries you devise a
> cunning plan to connect it from behind to the box.
>
> Brian

It's definitely a solid metal plate. It's stamped out of a sheet of
stainless steel. Just a flat square piece of metal screwed to the wall.

[Martin Brown]

On 03/06/2013 15:58, Ivan Dobsky wrote:
> "Brian Gaff" <Bri...@blueyonder.co.uk> wrote in message
> news:koi8j1$fra$1...@dont-email.me...
>> Is the box and screws and front panel earthed. If yes, then its not
>> working!
>> This electrostatic effect is often felt on brushed ally fronts of hi fis
>> etc, but if the earth is connected to it, you should not feel it at all.
>> Brian
>
> I've just had the multimeter out. I don't think the front plate is earthed.
> Measuring the resistance between it and other plates and screws in the
> vicinity also shows open circuit, whereas a measurement between any two
> other things shows that they are all connected. Even though this switch's
> metal box has an earth wire connected, and there is also one to the switch
> plate, I'll have to assume that the connection is lost somewhere in the wall
> or ceiling.
>
> My guess is that the strange tingling sensation is this electrostatic effect
> that BG mentions; or electricity induced in the faceplate due to the
> proximity of the mains cable. Or is that what 'electrostatic effect' means?

It isn't an electrostatic effect if it is being driven by mains voltage
at 50Hz it is capacitive leakage between adjacent conductors or in the
case of PC PSUs and HiFi the filter capacitors on the mains input
leaking to a no good earth connection. You can feel tiny currents but it
is as well to put things right before they get any worse!

Best guess is you have unearthed metal plate facing the end user.

--
Regards,
Martin Brown

[Ivan Dobsky]

"Martin Brown" <|||newspam|||@nezumi.demon.co.uk> wrote in message
news:av2rt.30088$rW2....@newsfe05.iad...

Capacitive leakage. Yes, I can imagine that.

I've tested for conductivity between this metal plate and the others, and
there is none. So, I'll have to find out where the earth wiring has broken.

> --
> Regards,
> Martin Brown

[Dave Plowman (News)]

In article <MLidncZDdPeDMjHM...@eclipse.net.uk>,

Ivan Dobsky <iv...@dobsky.com> wrote:
> I've just had the multimeter out. I don't think the front plate is
> earthed. Measuring the resistance between it and other plates and screws
> in the vicinity also shows open circuit, whereas a measurement between
> any two other things shows that they are all connected. Even though this
> switch's metal box has an earth wire connected, and there is also one to
> the switch plate, I'll have to assume that the connection is lost
> somewhere in the wall or ceiling.

How old is the wiring? As I said, at one time earths weren't required on
lighting circuits.

--
*All generalizations are false.

[John Rumm]

On 03/06/2013 16:26, Ivan Dobsky wrote:
> "Martin Brown" <|||newspam|||@nezumi.demon.co.uk> wrote in message

>> It isn't an electrostatic effect if it is being driven by mains voltage at
>> 50Hz it is capacitive leakage between adjacent conductors or in the case
>> of PC PSUs and HiFi the filter capacitors on the mains input leaking to a
>> no good earth connection. You can feel tiny currents but it is as well to
>> put things right before they get any worse!
>>
>> Best guess is you have unearthed metal plate facing the end user.
>
> Capacitive leakage. Yes, I can imagine that.
>
> I've tested for conductivity between this metal plate and the others, and
> there is none. So, I'll have to find out where the earth wiring has broken.

If its wired using "loop in" wiring, then next most likely place for
loss of earthing is at the ceiling rose where the switch cable will be
connected.

http://wiki.diyfaq.org.uk/index.php?title=House_Wiring_for_Beginners#Loop-in_Wiring



--
Cheers,

John.

/=================================================================\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\=================================================================/

[Ivan Dobsky]

"Dave Plowman (News)" <da...@davenoise.co.uk> wrote in message
news:5356179...@davenoise.co.uk...

> In article <MLidncZDdPeDMjHM...@eclipse.net.uk>,
> Ivan Dobsky <iv...@dobsky.com> wrote:
>> I've just had the multimeter out. I don't think the front plate is
>> earthed. Measuring the resistance between it and other plates and screws
>> in the vicinity also shows open circuit, whereas a measurement between
>> any two other things shows that they are all connected. Even though this
>> switch's metal box has an earth wire connected, and there is also one to
>> the switch plate, I'll have to assume that the connection is lost
>> somewhere in the wall or ceiling.
>
> How old is the wiring? As I said, at one time earths weren't required on
> lighting circuits.

Mid 80's

[Ivan Dobsky]

"John Rumm" <see.my.s...@nowhere.null> wrote in message
news:UqCdnfod5MP0UzHM...@brightview.co.uk...

> On 03/06/2013 16:26, Ivan Dobsky wrote:
>> "Martin Brown" <|||newspam|||@nezumi.demon.co.uk> wrote in message
>
>>> It isn't an electrostatic effect if it is being driven by mains voltage
>>> at
>>> 50Hz it is capacitive leakage between adjacent conductors or in the case
>>> of PC PSUs and HiFi the filter capacitors on the mains input leaking to
>>> a
>>> no good earth connection. You can feel tiny currents but it is as well
>>> to
>>> put things right before they get any worse!
>>>
>>> Best guess is you have unearthed metal plate facing the end user.
>>
>> Capacitive leakage. Yes, I can imagine that.
>>
>> I've tested for conductivity between this metal plate and the others, and
>> there is none. So, I'll have to find out where the earth wiring has
>> broken.
>
> If its wired using "loop in" wiring, then next most likely place for loss
> of earthing is at the ceiling rose where the switch cable will be
> connected.
>
> http://wiki.diyfaq.org.uk/index.php?title=House_Wiring_for_Beginners#Loop-in_Wiring
>

Thanks, I hope it's as simple as that.

[John Rumm]

On 03/06/2013 18:18, Ivan Dobsky wrote:
> "Dave Plowman (News)" <da...@davenoise.co.uk> wrote in message
> news:5356179...@davenoise.co.uk...
>> In article <MLidncZDdPeDMjHM...@eclipse.net.uk>,
>> Ivan Dobsky <iv...@dobsky.com> wrote:
>>> I've just had the multimeter out. I don't think the front plate is
>>> earthed. Measuring the resistance between it and other plates and screws
>>> in the vicinity also shows open circuit, whereas a measurement between
>>> any two other things shows that they are all connected. Even though this
>>> switch's metal box has an earth wire connected, and there is also one to
>>> the switch plate, I'll have to assume that the connection is lost
>>> somewhere in the wall or ceiling.
>>
>> How old is the wiring? As I said, at one time earths weren't required on
>> lighting circuits.
>
> Mid 80's

Earthed lighting circuits came in around 1966...

[Ivan Dobsky]

"Ivan Dobsky" <iv...@dobsky.com> wrote in message

news:feudnTs2Q_gzwTHM...@eclipse.net.uk...

> Is it normal to feel a very mild buzzing/tingling sensation from a metal
> light switch plate? You can only feel it if you gently run a finger at

> right angles to the 'grain' on the brushed metal surface. There's only one
> in the house, so I can't compare it to any others. It all looks fine
> inside the box.

Okay, I've done some testing with my multimeter. By connecting the probes
against the screws of several light switches, and nearby mains sockets. I
discovered that some of the light switch's earths aren't connected to some
of the mains sockets' earths. I'd have expected them all to be connected,
but I could be wrong. What's more, some of those screws are showing around
85V AC with another probe connected to a nearby mains socket screw, rising
to about 120 when you switch one of the affected lights on. I don't suppose
this is normal. None of the upstairs ones do this, but most of the
downstairs ones do.

Does any of this suggest anything obvious? I don't know what 120V feels
like, but I don't feel anything alarming when I touch the screws on an
affected switch. Although I might if I leaned over and touched a mains
socket screw at the same time.

[John Williamson]

Do the same test with a 20kohm/ volt or even a 1kohm/ volt analogue
meter, and they'll show zero volts to earth from the suspect faceplates.
The voltage you describe is caused by capacitive coupling, which has a
very high impedance at 50Hz, so while the virtual open circuit of a
digital multimeter input shows a voltage, the much lower input impedance
of a moving coil type meter will just short the voltage to earth. You
could get a similar result by licking the tip of your finger before
doing the brush test with it. The lower impedance when you touch it with
a damp finger shorts the current, and hence the tingling, to earth
before it affects your nerves.

The fault is that the metal faceplates that give you the tingle/ buzzing
feeling aren't earthed. If the wiring or the switch fails in the wrong
way, the faceplate could become fully live, which would give you rather
more than a slight tingling feeling...

[Ivan Dobsky]

"John Williamson" <johnwil...@btinternet.com> wrote in message
news:b14d2p...@mid.individual.net...

Thanks, I was hoping it would be something like that. I know that sometimes
testing with a digital meter can be misleading, but felt it would be too
optimistic to assume it was down to that.

> The fault is that the metal faceplates that give you the tingle/ buzzing
> feeling aren't earthed. If the wiring or the switch fails in the wrong
> way, the faceplate could become fully live, which would give you rather
> more than a slight tingling feeling...

The meter suggests that the metal faceplate earth is connected to the earth
at the ceiling rose, and also the faceplate on the other side of the room. I
think I'll inspect a few roses, and see if anything suggests itself.

[Steve Walker]

"Ivan Dobsky" <iv...@dobsky.com> wrote in message

news:HuCdnZeFwo-rnDDM...@eclipse.net.uk...

> The meter suggests that the metal faceplate earth is connected to the
> earth at the ceiling rose, and also the faceplate on the other side of the
> room. I think I'll inspect a few roses, and see if anything suggests
> itself.

Say hello to Mr Hoppy for me.

[John Rumm]

On 03/06/2013 21:48, Ivan Dobsky wrote:

> The meter suggests that the metal faceplate earth is connected to the earth
> at the ceiling rose, and also the faceplate on the other side of the room. I
> think I'll inspect a few roses, and see if anything suggests itself.

If you make up a long test lead extension, you should be able to test
from one light fitting to the next (you will have to guess at a likely
wiring order), but you may be able to narrow it down to one pair of
light fittings where the earth connection is open circuit between them.
Needless to say, any other fittings downstream of the break will also
appear to be disconnected from earth even if they are connected to each
other, creating an island type effect.

[Andy Wade]

On 03/06/2013 13:28, John Williamson wrote:
> [...] a few microamps of leakage current, and in your case, it means that
> the faceplate isn't earthed, and there's a very high resistance leakage
> path from the live inside the box to the faceplate. Worth investigating
> further in case something goes more seriously wrong.

It's more likely that the leakage is capacitive, resulting from the
capacitance between the line (L) conductor in the cable and the floating
earth/CPC.

--
Andy

[Ivan Dobsky]

"Steve Walker" <spam...@beeb.net> wrote in message
news:koj0ud$5m6$1...@dont-email.me...

Mr. Hoppyyyyy!

[Windmill]

"Ivan Dobsky" <iv...@dobsky.com> writes:


>"Bob Minchin" <bob.minc...@YOURHATntlworld.com> wrote in message
>news:kohvtt$q2i$1...@dont-email.me...
>> Clive George wrote:
>>> On 03/06/2013 10:06, Ivan Dobsky wrote:

>>>> Is it normal to feel a very mild buzzing/tingling sensation from a metal
>>>> light switch plate? You can only feel it if you gently run a finger at
>>>> right
>>>> angles to the 'grain' on the brushed metal surface. There's only one
>>>> in the
>>>> house, so I can't compare it to any others. It all looks fine inside the
>>>> box.
>>>

>>> Given you say you only feel it when stroking one way, might be worth
>>> checking if you still feel it with the relevant circuit switched off.
>>> (doing it blind, ie get somebody else to switch but not tell you which
>>> way, means you also eliminate potential bias, but I appreciate that may
>>> be getting harder :-) ). If so, it's something other than the leccy and
>>> not a problem, and you've saved yourself some grief.
>>>
>> Agreed.
>> The op also said it was buzzing and that could be a suppression choke
>> vibrating at 50/100 Hz which would be no problem at all.

>I probably should have used a word other than 'buzzing', but it is not a
>sound, just the way it feels, and I can't think of a better word. It's not
>really a tingle, either. You can only feel it when you very lightly brush
>your fingertips across the plate, and it seems to vibrate. You can't feel it
>when you just touch it. It's quite hard to describe. If you've ever walked
>under overhead cables with an umbrella, and gently rubbed the stem, you can
>feel something similar.

It's actually a very common feeling - but not on mains switches etc.;
that is odd. As others have said, suspect the earth connection.

Any time there's a tiny amount of capacitive coupling from the mains,
e.g. via one of those 'wall wart' adaptors, to something that isn't
earthed because it's supposedly insulated, you get that feeling.

The amount of current that flows is very small and wouldn't hurt you
(unless some serious failure occurred).
But it might well be enough to light up one of those neon-in-a-screwdriver
testers.

I think that if the earth on the switch box was good, but you were
standing on something which wasn't at earth potential as it should be
(damp stone floor in contact with a damaged cable, for example) you
might get the same effect. Or worse.


--
Windmill, Til...@Nonetel.com Use t m i l l
J.R.R. Tolkien:- @ O n e t e l . c o m
All that is gold does not glister / Not all who wander are lost

[Ivan Dobsky]

"Windmill" <spam-n...@Onetel.net.uk.invalid> wrote in message
news:Mnuu0...@freebie.onetel.net.uk...

It does, but it dims after about a second.

[Tim Watts]

On Monday 03 June 2013 21:25 Ivan Dobsky wrote in uk.d-i-y:

>
> "Ivan Dobsky" <iv...@dobsky.com> wrote in message
> news:feudnTs2Q_gzwTHM...@eclipse.net.uk...
>> Is it normal to feel a very mild buzzing/tingling sensation from a metal
>> light switch plate? You can only feel it if you gently run a finger at
>> right angles to the 'grain' on the brushed metal surface. There's only
>> one in the house, so I can't compare it to any others. It all looks fine
>> inside the box.
>
> Okay, I've done some testing with my multimeter. By connecting the probes
> against the screws of several light switches, and nearby mains sockets. I
> discovered that some of the light switch's earths aren't connected to some
> of the mains sockets' earths.

OK - you have earth faults with your system, somewhere...

I would strongly recommend a PIR (installation test) - not hugely expensive
in the grand scheme of things. That will discover all manner of problems
that are hard to find by other means.

Or you could have a look behind the plates (power proven off at CU of
course!) and see if there's anything obvious like the earth wire's fallen
out or is missing.

> I'd have expected them all to be connected,
> but I could be wrong. What's more, some of those screws are showing around
> 85V AC with another probe connected to a nearby mains socket screw, rising
> to about 120 when you switch one of the affected lights on. I don't
> suppose this is normal. None of the upstairs ones do this, but most of the
> downstairs ones do.

That's just capacitive leakage because to have no earth. However, if a live
wire falls off inside and touched the screw or backbox, you'd then have a
lethal situation.

>
> Does any of this suggest anything obvious? I don't know what 120V feels
> like, but I don't feel anything alarming when I touch the screws on an
> affected switch. Although I might if I leaned over and touched a mains
> socket screw at the same time.

--
Tim Watts Personal Blog: http://squiddy.blog.dionic.net/

http://www.sensorly.com/ Crowd mapping of 2G/3G/4G mobile signal coverage

Reading this on the web? See:
http://wiki.diyfaq.org.uk/index.php?title=Usenet

[John Rumm]

The nature of the unexpected voltage in this case is less significant
than the fact it has highlighted that you have a disconnected earth. So
all in all a much better way of finding out that by it not working as an
earth when really required!

[Dave Plowman (News)]

In article <srSdnSRtVIZYZjHM...@eclipse.net.uk>,

Ivan Dobsky <iv...@dobsky.com> wrote:
> Okay, I've done some testing with my multimeter. By connecting the
> probes against the screws of several light switches, and nearby mains
> sockets. I discovered that some of the light switch's earths aren't
> connected to some of the mains sockets' earths. I'd have expected them
> all to be connected, but I could be wrong. What's more, some of those
> screws are showing around 85V AC with another probe connected to a
> nearby mains socket screw, rising to about 120 when you switch one of
> the affected lights on. I don't suppose this is normal. None of the
> upstairs ones do this, but most of the downstairs ones do.

This is measuring the resistance or continuity? So more than one light
switch has no earth connection, relative to a nearby socket? Is there just
one lighting circuit in the house, or more than one? Can you measure
between two lighting switches by extending a test lead on the meter? It
won't be 100% accurate, but will show if there is a connection or not.

Sadly, finding out just where the break is can be very time consuming. I'd
start by opening up the CU to see if the earth is actually connected to
the lighting circuit there.

--
*If you try to fail and succeed, which have you done? *

[Ivan Dobsky]

"Dave Plowman (News)" <da...@davenoise.co.uk> wrote in message

news:5356736...@davenoise.co.uk...

> In article <srSdnSRtVIZYZjHM...@eclipse.net.uk>,
> Ivan Dobsky <iv...@dobsky.com> wrote:
>> Okay, I've done some testing with my multimeter. By connecting the
>> probes against the screws of several light switches, and nearby mains
>> sockets. I discovered that some of the light switch's earths aren't
>> connected to some of the mains sockets' earths. I'd have expected them
>> all to be connected, but I could be wrong. What's more, some of those
>> screws are showing around 85V AC with another probe connected to a
>> nearby mains socket screw, rising to about 120 when you switch one of
>> the affected lights on. I don't suppose this is normal. None of the
>> upstairs ones do this, but most of the downstairs ones do.
>
> This is measuring the resistance or continuity? So more than one light
> switch has no earth connection, relative to a nearby socket? Is there just
> one lighting circuit in the house, or more than one? Can you measure
> between two lighting switches by extending a test lead on the meter? It
> won't be 100% accurate, but will show if there is a connection or not.

I was measuring resistance between nearby faceplate screws - I don't know
another simple way to test continuity. The two nearest the CU do seem to be
earthed (there is no resistance between them, and nearby mains socket
faceplate screws). After that (I think I know what the sequence is, and it
doesn't appear to be a real loop, since another rose near the CU doesn't has
only two cables), they do all seem to be connected to each other, but not to
the last known earthed lighting faceplate, or any nearby mains faceplate.

If I discovered that one of the earth wires in the rose for that last known
earthed faceplate had come out, then that would explain it perfectly. But I
won't be able to check till I get home later.

[Dave Plowman (News)]

In article <naKdnYyxcp5YKzDM...@eclipse.net.uk>,

Ivan Dobsky <iv...@dobsky.com> wrote:
> I was measuring resistance between nearby faceplate screws - I don't
> know another simple way to test continuity. The two nearest the CU do
> seem to be earthed (there is no resistance between them, and nearby
> mains socket faceplate screws). After that (I think I know what the
> sequence is, and it doesn't appear to be a real loop, since another
> rose near the CU doesn't has only two cables), they do all seem to be
> connected to each other, but not to the last known earthed lighting
> faceplate, or any nearby mains faceplate.

Lighting circuits aren't a 'loop' or ring like the sockets. They are a
radial circuit. So a break in the earth will remove it from all downstream
of that break.

> If I discovered that one of the earth wires in the rose for that last
> known earthed faceplate had come out, then that would explain it
> perfectly. But I won't be able to check till I get home later.

I dunno if you know the history of this house since it was originally
wired. Does it use the sort of ceiling rose with all the connections
within them (loop in loop out)? If so, I'd first look for where one is
missing - replaced with perhaps a fitting mounted on the ceiling. Many of
these are of non UK origin, with no provision for an earth.

--
*Bills travel through the mail at twice the speed of cheques *

[Ivan Dobsky]

"Dave Plowman (News)" <da...@davenoise.co.uk> wrote in message

news:535675f...@davenoise.co.uk...

> In article <naKdnYyxcp5YKzDM...@eclipse.net.uk>,
> Ivan Dobsky <iv...@dobsky.com> wrote:
>> I was measuring resistance between nearby faceplate screws - I don't
>> know another simple way to test continuity. The two nearest the CU do
>> seem to be earthed (there is no resistance between them, and nearby
>> mains socket faceplate screws). After that (I think I know what the
>> sequence is, and it doesn't appear to be a real loop, since another
>> rose near the CU doesn't has only two cables), they do all seem to be
>> connected to each other, but not to the last known earthed lighting
>> faceplate, or any nearby mains faceplate.
>
> Lighting circuits aren't a 'loop' or ring like the sockets. They are a
> radial circuit. So a break in the earth will remove it from all downstream
> of that break.

Ah, I didn't know that. The roses do have the loop connections (like
terminal blocks) in them, and judging by the fact all except one have three
cables in them, I'd guess that my lighting circuit is in a C shape. I hope
it is - it would make the break easy to trace.

House was built in the 80's so these things are modern-ish.

[Ivan Dobsky]

"Ivan Dobsky" <iv...@dobsky.com> wrote in message
news:feudnTs2Q_gzwTHM...@eclipse.net.uk...

> Is it normal to feel a very mild buzzing/tingling sensation from a metal
> light switch plate? You can only feel it if you gently run a finger at
> right angles to the 'grain' on the brushed metal surface. There's only one
> in the house, so I can't compare it to any others. It all looks fine
> inside the box.

The problem is hopefully solved. My downstairs lights seem to be
daisy-chained together in a C shape. I opened up the rose of the last one
that had a good earth, and although there were three earth wires in the
sheath, only two were screwed into the terminal. Just being in the sheath
was not enough to make good contact (even though I'm sure there must have
been at least a little contact). So, the rest of the fittings down the chain
were not earthed.

Anyway, thanks all for your help and suggestions. It just shows that you
don't know what's lurking even in your own house.

[John Rumm]

On 04/06/2013 11:35, Ivan Dobsky wrote:
> "Dave Plowman (News)" <da...@davenoise.co.uk> wrote in message
> news:535675f...@davenoise.co.uk...
>> In article <naKdnYyxcp5YKzDM...@eclipse.net.uk>,
>> Ivan Dobsky <iv...@dobsky.com> wrote:
>>> I was measuring resistance between nearby faceplate screws - I don't
>>> know another simple way to test continuity. The two nearest the CU do
>>> seem to be earthed (there is no resistance between them, and nearby
>>> mains socket faceplate screws). After that (I think I know what the
>>> sequence is, and it doesn't appear to be a real loop, since another
>>> rose near the CU doesn't has only two cables), they do all seem to be
>>> connected to each other, but not to the last known earthed lighting
>>> faceplate, or any nearby mains faceplate.
>>
>> Lighting circuits aren't a 'loop' or ring like the sockets. They are a
>> radial circuit. So a break in the earth will remove it from all downstream
>> of that break.
>
> Ah, I didn't know that. The roses do have the loop connections (like
> terminal blocks) in them, and judging by the fact all except one have three
> cables in them, I'd guess that my lighting circuit is in a C shape. I hope
> it is - it would make the break easy to trace.

So the topology sounds like standard loop in. Power feed goes from the
MCB in the CU to the first ceiling rose, then from that to the next and
so on. Each rose has an additional connection to the switch. So three
cables to each rose except the last, which has no "out" cable.

Chances are you will find the break with a visual inspection in the
ceiling roses, however if not, repeat your test with the meter, looking
at the resistance between one rose's earth terminal and that of the next
one.

[Ivan Dobsky]

"John Rumm" <see.my.s...@nowhere.null> wrote in message

news:daCdnVDPRei9ZTDM...@brightview.co.uk...

I found it, quite early in the loop. Thanks for your help!

[Dave Plowman (News)]

In article <mvGdnc1bmorGaDDM...@eclipse.net.uk>,

Ivan Dobsky <iv...@dobsky.com> wrote:
> The problem is hopefully solved. My downstairs lights seem to be
> daisy-chained together in a C shape. I opened up the rose of the last
> one that had a good earth, and although there were three earth wires in
> the sheath, only two were screwed into the terminal. Just being in the
> sheath was not enough to make good contact (even though I'm sure there
> must have been at least a little contact). So, the rest of the fittings
> down the chain were not earthed.

Result. Probably been like that from new, and not tested thoroughly.

> Anyway, thanks all for your help and suggestions. It just shows that you
> don't know what's lurking even in your own house.

A nail through a cable which breaks the earth only can take much more
finding. ;-)

--
*Money isn't everything, but it sure keeps the kids in touch *

[Ivan Dobsky]

"Dave Plowman (News)" <da...@davenoise.co.uk> wrote in message

news:535694b...@davenoise.co.uk...

> In article <mvGdnc1bmorGaDDM...@eclipse.net.uk>,
> Ivan Dobsky <iv...@dobsky.com> wrote:
>> The problem is hopefully solved. My downstairs lights seem to be
>> daisy-chained together in a C shape. I opened up the rose of the last
>> one that had a good earth, and although there were three earth wires in
>> the sheath, only two were screwed into the terminal. Just being in the
>> sheath was not enough to make good contact (even though I'm sure there
>> must have been at least a little contact). So, the rest of the fittings
>> down the chain were not earthed.
>
> Result. Probably been like that from new, and not tested thoroughly.

Probably would never have thought to even look for it, if it hadn't been for
this switch problem.

>> Anyway, thanks all for your help and suggestions. It just shows that you
>> don't know what's lurking even in your own house.
>
> A nail through a cable which breaks the earth only can take much more
> finding. ;-)

Sounds like fun.

[John Rumm]

Well done!

[newshound]

On 03/06/2013 10:14, Martin Brown wrote:
> On 03/06/2013 10:06, Ivan Dobsky wrote:

>> Is it normal to feel a very mild buzzing/tingling sensation from a metal
>> light switch plate? You can only feel it if you gently run a finger at
>> right
>> angles to the 'grain' on the brushed metal surface. There's only one
>> in the
>> house, so I can't compare it to any others. It all looks fine inside the
>> box.
>

> No. It suggests that the metal isn't earthed and a leakage path to live.
>
> I expect it will also light one of those neon screwdrivers we are not
> supposed to use any more due to strange elfin safety rulz.
>

Doesn't suggest that to me. If it was live, a static finger should feel
it, and there would not be a grain direction effect. Sounds to me like a
mechanical phenomenon. Easy check would be a DVM (on AC volts setting)
between the plate and an earth. Typical DVM impedance should be high
enough to show some voltage if the leakage current is enough to feel.

[polygonum]

Sounds *exactly* like the effect noticed on Apple computers with
aluminium cases and non-earthed power supplies. If earthed, the tingling
disappears. So it seems very unlikely to be a mechanical phenomenon.

--
Rod

[John Rumm]

Yup, I have noted it on metal chassis equipment in the past...
You can normally sense it on some touch dimmers.

[tony sayer]

In article <b1em2l...@mid.individual.net>, polygonum
<rmoud...@vrod.co.uk> scribeth thus

I'd bet that the earth connection in the switch box isn't connected
there or at the other end of the cable and all this is, is just
Capactive leakage..
--
Tony Sayer

[polygonum]

Some of the Apple power supplies are earthed when used with a cable but
not when plugged directly in. (Hmm, think it is that way round...) So
simply by using/not using the cable you can switch the tingle on and off.

--
Rod