I touched one of my electrical sockets the other day and could feel
electricity (they have metal covers). It wasn't powerful enough to hurt
like it did when I touched the live wire to the cooker, but it was
fairly strong and I could feel the 50hz.

Been trying all day today and I can't electrocute myself this time, darn
it. What could the fault possibly have been? I've unscrewed the thing
and everything seems to be firmly attached inside including the earth
loop. The adjacent socket didn't have the same problem, although I
wondered whether I might have been touching something else that's live
and was just creating a circuit by touching the socket. But nothing
seems a likely candidate.

Any ideas greatly appreciated. (Obviously I'm keen to sort this out and
don't really take electrical safety lightly!)

I touched one of my electrical sockets the other day and could feel
electricity (they have metal covers). It wasn't powerful enough to hurt
like it did when I touched the live wire to the cooker, but it was
fairly strong and I could feel the 50hz.
snip
Any ideas greatly appreciated. (Obviously I'm keen to sort this out and
don't really take electrical safety lightly!)

Do you know what sort of electricity supply you have to your premises ?
(are you fed from overhead lines or cables clipped along a row of houses
or is the cable underground for as far as the eye can see)

Bear in mind that electricity companies are not legally obliged to
provide an earth, and in many cases may not be able to provide one for
one of several reasons:

- structures of a temporary nature (portacabins etc)
- farms or where livestock are held
- overhead lines often don`t have an earth provision
- same goes for clipped (sometimes known as cleated or mural) wiring
- network conditions may not allow... one area nearby has a "tidal" earth
where the area is essentially built on sand. When the tide comes in you
get a great earth, but when it goes out again...

Do you have any sort of safety devices fitted, like an RCD ? - if you
have an older type of device it might be worth getting that replaced for
a start (my knowledge is a little weak in this area).

When you had the front of the socket off, did you notice any damage to
the insulation ? (sometimes cables can be pressed hard against each other
damaging the insulation)

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"Haddock" wrote in message
...

I touched one of my electrical sockets the other day and could feel
electricity (they have metal covers). It wasn't powerful enough to hurt
like it did when I touched the live wire to the cooker, but it was
fairly strong and I could feel the 50hz.

Been trying all day today and I can't electrocute myself this time, darn
it. What could the fault possibly have been? I've unscrewed the thing
and everything seems to be firmly attached inside including the earth
loop. The adjacent socket didn't have the same problem, although I
wondered whether I might have been touching something else that's live
and was just creating a circuit by touching the socket. But nothing
seems a likely candidate.

Any ideas greatly appreciated. (Obviously I'm keen to sort this out and
don't really take electrical safety lightly!)

If it was just a tingle, for a second or so, then it could just have been
static building up on your clothes (nylon underwear) and being drawn away to
earth through the socket cover.


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Colin Wilson wrote:
Do you know what sort of electricity supply you have to your premises ?
(are you fed from overhead lines or cables clipped along a row of houses
or is the cable underground for as far as the eye can see)

No overhead lines around here -- very urban. The city's main substation
is less than a mile away.

Bear in mind that electricity companies are not legally obliged to
provide an earth, and in many cases may not be able to provide one for
one of several reasons:

It's a converted mid-victorian terrace flat. The wiring in the flat is
great but the part downstairs where the metres are is very old and dodgy
so there could be anything going on.

- same goes for clipped (sometimes known as cleated or mural) wiring

Is that something old? Could be that if so.

Do you have any sort of safety devices fitted, like an RCD ? - if you
have an older type of device it might be worth getting that replaced for
a start (my knowledge is a little weak in this area).

No I don't have an RCD but I thinking I really need one. They are just
installed in series before the consumer unit aren't they, sounds like an
easy job?

When you had the front of the socket off, did you notice any damage to
the insulation ? (sometimes cables can be pressed hard against each other
damaging the insulation)

I'll have another check tomorrow when I'm more sober.......

Thanks for your help

If it was just a tingle, for a second or so, then it could just have been
static building up on your clothes (nylon underwear) and being drawn away
to
earth through the socket cover.

and in particular brown nylon y-fronts.
If this is what you're wearing then go back and lick the cooker wires and
get out of the gene pool.

In article , BigWallop
writes

"Haddock" wrote in message
...

I touched one of my electrical sockets the other day and could feel
electricity (they have metal covers). It wasn't powerful enough to hurt
like it did when I touched the live wire to the cooker, but it was
fairly strong and I could feel the 50hz.

Been trying all day today and I can't electrocute myself this time, darn
it. What could the fault possibly have been? I've unscrewed the thing
and everything seems to be firmly attached inside including the earth
loop. The adjacent socket didn't have the same problem, although I
wondered whether I might have been touching something else that's live
and was just creating a circuit by touching the socket. But nothing
seems a likely candidate.

Any ideas greatly appreciated. (Obviously I'm keen to sort this out and
don't really take electrical safety lightly!)

If it was just a tingle, for a second or so, then it could just have been
static building up on your clothes (nylon underwear) and being drawn away to
earth through the socket cover.

Unlikely to be static because:-
I could feel the 50hz.
I have not yet come across 50Hz static.

I would be tempted to check that both sockets are properly earthed, both
the one you touched and the adjacent one. Checking that they are both at
the same potential with an ohm meter would be a good start. Try it on ac
volts first of all. It is not unheard of for earth wire to become
disconnected elsewhere in the circuit and this would not at first be
apparent as it would not stop appliances from working.
Best of luck and take care.




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--
-- Bill

On Sun, 25 Jan 2004 21:53:06 UTC, "Suz" wrote:


If it was just a tingle, for a second or so, then it could just have been
static building up on your clothes (nylon underwear) and being drawn away
to
earth through the socket cover.

and in particular brown nylon y-fronts.

Much safer wearing green ones with yellow stripes....

--
Bob Eager
begin by not using Outlook Express...

No overhead lines around here -- very urban. The city's main substation
is less than a mile away.

Doesn`t mean the mains in the area aren`t old and provide you with an
earth...

It's a converted mid-victorian terrace flat. The wiring in the flat is
great but the part downstairs where the metres are is very old and dodgy
so there could be anything going on.

Are you paying rent, or is it privately owned ? - i`m wondering whether a
landlord might have any responsibility for wiring. The submain will
probably belong to the landlord and not the electricity company, and it
isn`t unknown for these to fail. As the electricity supplier isn`t
obliged to provide an earth, it will probably be the landlords
responsibility to make sure adequate provision is in place. Not sure what
the hell you`d need to do it its privately owned :-}

- same goes for clipped (sometimes known as cleated or mural) wiring
Is that something old? Could be that if so.

You`d see it clipped along the front of the houses adjacent i`d guess...

No I don't have an RCD but I thinking I really need one. They are just
installed in series before the consumer unit aren't they, sounds like an
easy job?

Where`s your consumer unit (fuse board) - i`m guessing its in the flat.

The ideal way would probably be to fit a new consumer unit that can split
the load into RCD protected and non-RCD protected (lights are generally
better off non-RCD protected from what I remember of sparking, but its
been a while :-} )

If you are paying rent though, i`d report it to the landlord and ask him
to get it checked out.

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In article ,
BigWallop wrote:
If it was just a tingle, for a second or so, then it could just have
been static building up on your clothes (nylon underwear) and being
drawn away to earth through the socket cover.


But you don't get a tingle from static - it's a sharp shock which then
stops. A 'leak' of any sort from the mains carries on.

--
*Why doesn't glue stick to the inside of the bottle?

Dave Plowman London SW 12
RIP Acorn

In uk.d-i-y, BigWallop wrote:

If it was just a tingle, for a second or so, then it could just have been
static building up on your clothes (nylon underwear) and being drawn away to
earth through the socket cover.

No chance. Static builds up to si high a voltage that even with several
megaohms in the path to earth, it discharges damn quickly, and won't give
any kind of "sustained 50Hz tingle" like wot our original poster got. (And
if there was that kind of resistance in the path to earth, the socket's
earth connection's not exactly in order!).

From the details given, there's a (possibly intermittent) fault which needs
sorting out. It's not clear from what we've heard whether the socket was
the source of the 'tingle', with mains current passing through the OP's
body on its way to earth, or its 'sink' - for example, if there's a
floorboard nail which is just about contact with a live (only), and the OP
stands on it, the surrounding floorboards won't give a decent path to
earth so our man won't feel anything; but touching a well-earthed point
- the socket cover if all the wiring's in order - creates a path to earth
which our man can feel. (In such a case the strength of the 'tingle' is
much dependant on how effective a contact he has with the source: do a
trick like this in bare feet and you might not wake up at all :-(

Other uglies can happen with TV/video/sat etc. kit: some of these have
two-pin mains connectors, and then internal circuitry which makes the
aerial outer float to halfway between the live and neutral voltages. The
resistance is high enough not to make the amount of current which flows
dangerous to life, but you still feel a real and unpleasant tingle if
you become the earth path for this voltage.

I'd definitely want to know what caused the 'tingle': what's an unpleasant
weirdness on one occasion can become something much more dangerous next
time.

Stefek

No I don't have an RCD but I thinking I really need one. They are just
installed in series before the consumer unit aren't they, sounds like an
easy job?

Where`s your consumer unit (fuse board) - i`m guessing its in the flat.

The ideal way would probably be to fit a new consumer unit that can split
the load into RCD protected and non-RCD protected (lights are generally
better off non-RCD protected from what I remember of sparking, but its
been a while :-} )

If you're in a 1st floor flat then you dont really need an RCD for
anything other than the shower. The RCD is required for socket outlets
that are reasonably expected to supply portable equipment for use
outdoors. Not all that likely in an upstairs flat.


SJW
A.C.S. Ltd.

If you're in a 1st floor flat then you dont really need an RCD for
anything other than the shower. The RCD is required for socket outlets
that are reasonably expected to supply portable equipment for use
outdoors. Not all that likely in an upstairs flat.

What about leakage through the consumer to any bonded pipework etc ?

At least the RCD would trip rather than still being potentially fatal.

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On Mon, 26 Jan 2004 01:14:37 -0000, Colin Wilson
wrote:

If you're in a 1st floor flat then you dont really need an RCD for
anything other than the shower. The RCD is required for socket outlets
that are reasonably expected to supply portable equipment for use
outdoors. Not all that likely in an upstairs flat.

What about leakage through the consumer to any bonded pipework etc ?

Pardon?

At least the RCD would trip rather than still being potentially fatal.

Working along those lines would that not apply to lighting circuits on
a 'normal' split load setup in a 'normal' house?


SJW
A.C.S. Ltd.

Working along those lines would that not apply to lighting circuits on
a 'normal' split load setup in a 'normal' house?

Lights can be prone to nuisance trips when lamps blow, but (and i`m
probably wrong, haven`t played with wiring for years :-} ) I think the
general idea is lights tend to have less that can go wrong with them, and
taking the safety factor of being thrown into complete darkness, the RCD
tends to go onto "power" circuits :-}

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On Mon, 26 Jan 2004 21:24:29 -0000, Colin Wilson
wrote:

Working along those lines would that not apply to lighting circuits on
a 'normal' split load setup in a 'normal' house?

Lights can be prone to nuisance trips when lamps blow, but (and i`m
probably wrong, haven`t played with wiring for years :-} ) I think the
general idea is lights tend to have less that can go wrong with them, and
taking the safety factor of being thrown into complete darkness, the RCD
tends to go onto "power" circuits :-}

Yes, quite right, but...
Assuming we're talking about a installation up to required standards
then there would be adequate earth bonding to ensure zero potential
between pipework and other surfaces, thus no current to travel
anywhere surely.
If you were going to start altering the consumer unit on an old
installation it would not be a good idea to ignore the other aspects
affecting the safety of the installation, e.g. earthing arrangements.
Although in one way of thinking you are not making it any worse you
may well be not be making it better.
Yes, if there wasn't adequate earthing in the property I would say you
would be correct and there could be different potentials between
adjecant exposed metallic surfaces, that's what the earthing is
designed to prevent, when done correctly.


SJW
A.C.S. Ltd.

"Lurch" wrote in message
...
On Mon, 26 Jan 2004 21:24:29 -0000, Colin Wilson
wrote:

Working along those lines would that not apply to lighting circuits on
a 'normal' split load setup in a 'normal' house?

Lights can be prone to nuisance trips when lamps blow, but (and i`m
probably wrong, haven`t played with wiring for years :-} ) I think the
general idea is lights tend to have less that can go wrong with them, and
taking the safety factor of being thrown into complete darkness, the RCD
tends to go onto "power" circuits :-}

Yes, quite right, but...
Assuming we're talking about a installation up to required standards
then there would be adequate earth bonding to ensure zero potential
between pipework and other surfaces, thus no current to travel
anywhere surely.
If you were going to start altering the consumer unit on an old
installation it would not be a good idea to ignore the other aspects
affecting the safety of the installation, e.g. earthing arrangements.
Although in one way of thinking you are not making it any worse you
may well be not be making it better.
Yes, if there wasn't adequate earthing in the property I would say you
would be correct and there could be different potentials between
adjecant exposed metallic surfaces, that's what the earthing is
designed to prevent, when done correctly.


SJW
A.C.S. Ltd.

There was a fault in my parent's house where the old aluminium earth wiring
had broken. This was revealed when thanks to this ridiculous obsession with
bonding everything to "earth" in the bathroom, a second fault made all the
fittings live. The equipotential bit certainly worked - shame it was all at
240v and not 0v.

The moral of this story? Connecting all the metal bits of a bathroom
together isn't necessarily such a safe thing to have to do.

Bob

In article ,
Bob wrote:
There was a fault in my parent's house where the old aluminium earth
wiring had broken. This was revealed when thanks to this ridiculous
obsession with bonding everything to "earth" in the bathroom, a second
fault made all the fittings live. The equipotential bit certainly
worked - shame it was all at 240v and not 0v.

The moral of this story? Connecting all the metal bits of a bathroom
together isn't necessarily such a safe thing to have to do.

The moral of this story is to do things correctly - they should have been
bonded to a true earth, not just some earth wire anywhere. That's why
*proper* earth bonding involves running back to the central earth point -
not just tapping off ring main earths etc.

--
*Where there's a will, I want to be in it.

Dave Plowman London SW 12
RIP Acorn

In uk.d-i-y, Bob wrote:

There was a fault in my parent's house where the old aluminium earth wiring
had broken. This was revealed when thanks to this ridiculous obsession with
bonding everything to "earth" in the bathroom, a second fault made all the
fittings live. The equipotential bit certainly worked - shame it was all at
240v and not 0v.

The moral of this story? Connecting all the metal bits of a bathroom
together isn't necessarily such a safe thing to have to do.

Do explain further, Bob: tell us how the "ridiculous obsession" meant that
"all" the fittings were "at" 240V. Hint: that'd be 240V relative to what?

Clearly, if *some* conductive surfaces in a bathroom become live, i.e.
attain the potential of the incoming mains' live wire, and stay at
that potential without causing a large fault current to flow so interrupting
the supply (which is the first line of defence) because of the absence of
an effective connection to earth, while *other* conductive surfaces *are*
effectively connected to earth, there will be a shocking potential difference
between the first and second group of surfaces. And that's dangerous. And
avoiding that difference is exactly why everything with exposed metal
surfaces which might foreseeably become live is supposed to be bonded
together. That's the whole idea of, and the reason for the name of,
"supplementary" bonding. Nowhere in that idea, or its detailed implementation
in millions of households, is there a requirment that this stuff be bonded
"to earth", btw: the point is to provide *supplementary* protection so that
*regardless* of whether the whole "house earth" is at local ground potential,
there's no dangerous *local* difference in potentials between the different
conductive objects *in* *the* *bathroom* *itself*.

There are indeed other ways of guarding against dangers to life from
electrical faults; and avoiding *any* path to earth in a particular
working environment is one such. But it's not a practical option for
normal bathrooms in normal houses, wot with all those copper cold water
pipes and the like. (Yes, Hep2O does make a difference; and the IEE Regs
recognise that difference, making rather different recommendations for
all-plastic plumbing installs.)

But, as I said, please do explain your comments about the ridiculous
obsession...

Stefek

Bob wrote:

There was a fault in my parent's house where the old aluminium earth wiring
had broken. This was revealed when thanks to this ridiculous obsession with
bonding everything to "earth" in the bathroom, a second fault made all the
fittings live. The equipotential bit certainly worked - shame it was all at
240v and not 0v.

The moral of this story? Connecting all the metal bits of a bathroom
together isn't necessarily such a safe thing to have to do.

Sounds OK to me, since you could *only* touch things at 240 volts
(everything conductive is bonded together) you still can't get a
shock.

This is the whole point of supplementary bonding, it gives a 'second
line of defence' if the earth is faulty for some reason.

--
Chris Green

Dave Plowman wrote:
In article ,
Bob wrote:
There was a fault in my parent's house where the old aluminium earth
wiring had broken. This was revealed when thanks to this ridiculous
obsession with bonding everything to "earth" in the bathroom, a second
fault made all the fittings live. The equipotential bit certainly
worked - shame it was all at 240v and not 0v.

The moral of this story? Connecting all the metal bits of a bathroom
together isn't necessarily such a safe thing to have to do.

The moral of this story is to do things correctly - they should have been
bonded to a true earth, not just some earth wire anywhere. That's why
*proper* earth bonding involves running back to the central earth point -
not just tapping off ring main earths etc.

There isn't actually a requirement for supplementary bonding to be
connected to earth, in many cases it will be, but only because some
part of the supplementary bonded stuff happens to be earthed for other
reasons.

The supplementary bonding will do its job even if it's not connected to
earth, if everything conductive in the bathroom is bonded together you
can't get a shock unless you stick your hand out of the door and touch
something earthy outside.

--
Chris Green

The moral of this story? Connecting all the metal bits of a bathroom
together isn't necessarily such a safe thing to have to do.

Indeed. If you can eliminate earths altogether the protection is better. The
IEE recommend that you use plastic pipework so that you can avoid the need
for supplementary bonding.

However, if you DO have metal pipework, then supplementary bonding is safer
because that earth fault that makes something 240V does one of two things:

1. It causes a major short to earth, tripping an MCB/RCD before you have a
chance to be shocked.
2. If (1) doesn't occur, it means that everything is at 240V, so you don't
get shocked. Have you seen those pictures of people working on live
multi-kilovolt systems safely simply by only touching the live and not the
earth?

Christian.

Christian McArdle writes
The moral of this story? Connecting all the metal bits of a bathroom
together isn't necessarily such a safe thing to have to do.
However, if you DO have metal pipework, then supplementary bonding is safer
because that earth fault that makes something 240V does one of two things:

1. It causes a major short to earth, tripping an MCB/RCD before you have a
chance to be shocked.
2. If (1) doesn't occur, it means that everything is at 240V, so you don't
get shocked.

Unfortunately, you do. Even if all the metalwork is only at 120V.
Everything was fine until someone used bath salts so that the water
going down the plastic drain to the old [broken?] earthenware drain in
the yard was conductive.
Stand in draining water, get nasty belt off mixer.
I didn't altogether believe this, went over to the friends house and
tried it. Once was enough.
Contractor had used armour of cable for earth continuity, terminating it
very professionally in a proper gland onto the Consumer Unit casing.
Which was plastic.
Filters on a big PC system, TV's etc then took "earth" to 120V.
--
roger

delete x's to email

In uk.d-i-y, Christian McArdle wrote:

Indeed. If you can eliminate earths altogether the protection is better. The
IEE recommend that you use plastic pipework so that you can avoid the need
for supplementary bonding.

Not quite sure they go that far; certainly with plastic plumbing there is
less that needs bonding, e.g. taps don't; but other electrical gear
such as electric showers, heaters, shaver points, etc. will still need
cross-bonding.

On Tue, 27 Jan 2004 09:56:04 -0000, "Bob"
wrote:


"Lurch" wrote in message
...
On Mon, 26 Jan 2004 21:24:29 -0000, Colin Wilson
wrote:

Working along those lines would that not apply to lighting circuits on
a 'normal' split load setup in a 'normal' house?

Lights can be prone to nuisance trips when lamps blow, but (and i`m
probably wrong, haven`t played with wiring for years :-} ) I think the
general idea is lights tend to have less that can go wrong with them, and
taking the safety factor of being thrown into complete darkness, the RCD
tends to go onto "power" circuits :-}

Yes, quite right, but...
Assuming we're talking about a installation up to required standards
then there would be adequate earth bonding to ensure zero potential
between pipework and other surfaces, thus no current to travel
anywhere surely.
If you were going to start altering the consumer unit on an old
installation it would not be a good idea to ignore the other aspects
affecting the safety of the installation, e.g. earthing arrangements.
Although in one way of thinking you are not making it any worse you
may well be not be making it better.
Yes, if there wasn't adequate earthing in the property I would say you
would be correct and there could be different potentials between
adjecant exposed metallic surfaces, that's what the earthing is
designed to prevent, when done correctly.


SJW
A.C.S. Ltd.

There was a fault in my parent's house where the old aluminium earth wiring
had broken. This was revealed when thanks to this ridiculous obsession with
bonding everything to "earth" in the bathroom, a second fault made all the
fittings live. The equipotential bit certainly worked - shame it was all at
240v and not 0v.

The moral of this story? Connecting all the metal bits of a bathroom
together isn't necessarily such a safe thing to have to do.

Not sure if you're agreeing or disagreeing with me, I'm sure it'll
come clear in a minute. Meanwhile:-
That's what I said. Connecting the metalwork in the bathroom together
is half the job, connecting all the other bits of metal in the
building together and also to a reliable earth point would be the
other half.


SJW
A.C.S. Ltd.

There was a fault in my parent's house where the old aluminium earth
wiring had broken. This was revealed when thanks to this ridiculous
obsession with bonding everything to "earth" in the bathroom, a second
fault made all the fittings live. The equipotential bit certainly
worked - shame it was all at 240v and not 0v.

The moral of this story? Connecting all the metal bits of a bathroom
together isn't necessarily such a safe thing to have to do.

The moral of this story is to do things correctly - they should have been
bonded to a true earth, not just some earth wire anywhere. That's why
*proper* earth bonding involves running back to the central earth point -
not just tapping off ring main earths etc.

There isn't actually a requirement for supplementary bonding to be
connected to earth, in many cases it will be, but only because some
part of the supplementary bonded stuff happens to be earthed for other
reasons.

Although if you add all the seperate bits of bonding and earthing
regulations it basically all adds up to "connect all metal bits
together"
The supplementary bonding connected to metalwork will be connected to
the main service pipes, (even with plastic in the middle, those bits
need to be 'bridged'), they will be connected to each other at the
mains end with equipotential bonding thus connecting all exposed metal
work.
This will also connect all socket screws, light fittings etc..
So there is no 'direct' regulation stating that supplementary bonding
should be connected to earth but the earthing system as a whole is
designed so that it is.

The supplementary bonding will do its job even if it's not connected to
earth, if everything conductive in the bathroom is bonded together you
can't get a shock unless you stick your hand out of the door and touch
something earthy outside.




SJW
A.C.S. Ltd.

Lurch wrote:

There isn't actually a requirement for supplementary bonding to be
connected to earth, in many cases it will be, but only because some
part of the supplementary bonded stuff happens to be earthed for other
reasons.

Although if you add all the seperate bits of bonding and earthing
regulations it basically all adds up to "connect all metal bits
together"
The supplementary bonding connected to metalwork will be connected to
the main service pipes, (even with plastic in the middle, those bits
need to be 'bridged'), they will be connected to each other at the
mains end with equipotential bonding thus connecting all exposed metal
work.

If there are mostly plastic pipes there is no requirement to bond any
metal bits on them (e.g. taps or maybe the odd union), thus this
*won't* be connected to the main incoming pipework, which is quite
likely to be plastic nowadays anyaway. So no necessary connection to
earth here.


This will also connect all socket screws, light fittings etc..
So there is no 'direct' regulation stating that supplementary bonding
should be connected to earth but the earthing system as a whole is
designed so that it is.

There shouldn't be any socket in the bathroom. If there is nothing
electrical with exposed metal parts (quite likely in a bathroom) there
is again no need for the supplementary bonding to be connected to the
electrical earth. (Is that right, I don't have my OSG to hand, it
*may* be that electrical equipment earths should be connected to
supplementary bonding, not absolutely sure - however if there's no
electrical equipment in the zones my comment still applies)

--
Chris Green

certainly with plastic plumbing there is less that needs bonding,
e.g. taps don't;

Indeed. However, they are keen to have you install plastic plumbing so that
the metal bath and radiators don't need bonding. These are large areas
likely to be touched.

but other electrical gear such as electric showers, heaters, shaver
points,
etc. will still need cross-bonding.

Yes, but these are often not large areas. Also, I have none of these devices
in my bathroom. Nor does my mother's house and nor did my last house. I do
have metal pipework, though, so I've still got to have bonding.

Christian.

wrote in message
...
In uk.d-i-y, Bob wrote:

There was a fault in my parent's house where the old aluminium earth
wiring
had broken. This was revealed when thanks to this ridiculous obsession
with
bonding everything to "earth" in the bathroom, a second fault made all
the
fittings live. The equipotential bit certainly worked - shame it was
all at
240v and not 0v.

The moral of this story? Connecting all the metal bits of a bathroom
together isn't necessarily such a safe thing to have to do.

Do explain further, Bob: tell us how the "ridiculous obsession" meant that
"all" the fittings were "at" 240V. Hint: that'd be 240V relative to what?

Clearly, if *some* conductive surfaces in a bathroom become live, i.e.
attain the potential of the incoming mains' live wire, and stay at
that potential without causing a large fault current to flow so
interrupting
the supply (which is the first line of defence) because of the absence of
an effective connection to earth, while *other* conductive surfaces *are*
effectively connected to earth, there will be a shocking potential
difference
between the first and second group of surfaces. And that's dangerous. And
avoiding that difference is exactly why everything with exposed metal
surfaces which might foreseeably become live is supposed to be bonded
together. That's the whole idea of, and the reason for the name of,
"supplementary" bonding. Nowhere in that idea, or its detailed
implementation
in millions of households, is there a requirment that this stuff be bonded
"to earth", btw: the point is to provide *supplementary* protection so
that
*regardless* of whether the whole "house earth" is at local ground
potential,
there's no dangerous *local* difference in potentials between the
different
conductive objects *in* *the* *bathroom* *itself*.

There are indeed other ways of guarding against dangers to life from
electrical faults; and avoiding *any* path to earth in a particular
working environment is one such. But it's not a practical option for
normal bathrooms in normal houses, wot with all those copper cold water
pipes and the like. (Yes, Hep2O does make a difference; and the IEE Regs
recognise that difference, making rather different recommendations for
all-plastic plumbing installs.)

But, as I said, please do explain your comments about the ridiculous
obsession...

Stefek

240V relative to the floor they were standing on, of course. Just because
all the metal bits are joined together doesn't mean that if they end up
connected to the live instead of earth wire that you won't get a shock. You
could always try holding a live wire if you don't think I'm right.

I did post a couple of years ago about this subject - ie what is the point
of earth bonding, but no-one could answer at the time. From recent posts I
can see what the reason is, but my point is that earth bonding protects
against one kind of fault only. I'm just giving an example where it made
the fault more dangerous.

Bob

240V relative to the floor they were standing on, of course. Just because
all the metal bits are joined together doesn't mean that if they end up
connected to the live instead of earth wire that you won't get a shock.

What sort of bathroom floor has enough conductivity to give you a powerful
enough shock to kill you? Typically, a bathroom floor will be timber,
plastic, stone or ceramic. All are excellent insulators and will not support
the levels of current needed for a dangerous current flow.

Christian.

On 28 Jan 2004 09:20:35 GMT, wrote:

Lurch wrote:

There isn't actually a requirement for supplementary bonding to be
connected to earth, in many cases it will be, but only because some
part of the supplementary bonded stuff happens to be earthed for other
reasons.

Although if you add all the seperate bits of bonding and earthing
regulations it basically all adds up to "connect all metal bits
together"
The supplementary bonding connected to metalwork will be connected to
the main service pipes, (even with plastic in the middle, those bits
need to be 'bridged'), they will be connected to each other at the
mains end with equipotential bonding thus connecting all exposed metal
work.

If there are mostly plastic pipes there is no requirement to bond any
metal bits on them (e.g. taps or maybe the odd union), thus this
*won't* be connected to the main incoming pipework, which is quite
likely to be plastic nowadays anyaway. So no necessary connection to
earth here.

O.k, if the installation is all in plastic then yes, but my comments
were more based on the more common installations of metalwork, (which
is what the posters saying it is wrong to have supplementary earthing
have so that is what I chose to comment on, plastic isn't relevant to
this particular conversation).

This will also connect all socket screws, light fittings etc..
So there is no 'direct' regulation stating that supplementary bonding
should be connected to earth but the earthing system as a whole is
designed so that it is.

There shouldn't be any socket in the bathroom.

I never said there should, I was meaning in the property in general.

If there is nothing
electrical with exposed metal parts (quite likely in a bathroom) there
is again no need for the supplementary bonding to be connected to the
electrical earth.

No, you would still have to bond pipework together.

(Is that right, I don't have my OSG to hand, it
*may* be that electrical equipment earths should be connected to
supplementary bonding,

I didn't say connect it directly, I said it is connected by default,
i.e. all earths connected together at the CU. More than likely the
earth path from supplementary bonded metalwork will end up connected
here.

not absolutely sure - however if there's no
electrical equipment in the zones my comment still applies)




SJW
A.C.S. Ltd.

In article ,
wrote:
Not quite sure they go that far; certainly with plastic plumbing there is
less that needs bonding, e.g. taps don't; but other electrical gear
such as electric showers, heaters, shaver points, etc. will still need
cross-bonding.

Do you really need to cross-bond a shaver socket given that the only
exposed metalwork is the fixing screws?

--
*If all is not lost, where the hell is it?

Dave Plowman London SW 12
RIP Acorn

240V relative to the floor they were standing on, of course. Just because
all the metal bits are joined together doesn't mean that if they end up
connected to the live instead of earth wire that you won't get a shock. You
could always try holding a live wire if you don't think I'm right.

I did post a couple of years ago about this subject - ie what is the point
of earth bonding, but no-one could answer at the time. From recent posts I
can see what the reason is, but my point is that earth bonding protects
against one kind of fault only. I'm just giving an example where it made
the fault more dangerous.

So you're saying it wasn't the bonding that caused the metalwork to
become live but two seperate faults elsewhere in the installation.
If you didn't have the bonding you would have found other faults or
problems from not having bonding anywhere.
If you would care to have go on google you will find plenty of
articles on bonding, why you should do it, how it works etc..


SJW
A.C.S. Ltd.

In article ,
Christian McArdle wrote:
What sort of bathroom floor has enough conductivity to give you a
powerful enough shock to kill you? Typically, a bathroom floor will be
timber, plastic, stone or ceramic. All are excellent insulators and will
not support the levels of current needed for a dangerous current flow.

I'd not fancy my chances of standing barefoot on a wet concrete floor and
touching a 240 supply with wet hands. You try it if you want. ;-)

--
*Verbs HAS to agree with their subjects *

Dave Plowman London SW 12
RIP Acorn

On Wed, 28 Jan 2004 13:36:41 +0000 (GMT), Dave Plowman
wrote:

In article ,
wrote:
Not quite sure they go that far; certainly with plastic plumbing there is
less that needs bonding, e.g. taps don't; but other electrical gear
such as electric showers, heaters, shaver points, etc. will still need
cross-bonding.

Do you really need to cross-bond a shaver socket given that the only
exposed metalwork is the fixing screws?

According to the regs, yes.
I did a bit of sub-contacting to a firm a few years back, before earth
bonding became daft. Being useless in every other aspect, (the firm,
not me), I was surprised when I went on a 2nd fix of a bathroom
extension to find a 4mm earth connected to anything in the room, the
shower and exposed metalwork as normal but also to the light fitting,
fan, shaver light, and anything else with a screew on it, whether it
could be touched or not. Everything in the room was double insulated,
bar the shower.


SJW
A.C.S. Ltd.

Lurch wrote:

I didn't say connect it directly, I said it is connected by default,
i.e. all earths connected together at the CU. More than likely the
earth path from supplementary bonded metalwork will end up connected
here.

But the whole point is that "supplementary bonding" *isn't* an earth
connection and doesn't work by being connected to earth.

It may well be that in many installations (e.g. where all pipework is
copper) the supplementary bonded metalwork in the bathroom is
connected to earth but that isn't what makes it useful.

--
Chris Green

Bob wrote:

240V relative to the floor they were standing on, of course. Just because
all the metal bits are joined together doesn't mean that if they end up
connected to the live instead of earth wire that you won't get a shock. You
could always try holding a live wire if you don't think I'm right.

The floor isn't conductive so, no shock. You most certainly *can*
grap a live wire and not get a shock, in fact it's the commonest
situation in my experience as one nearly always wears rubber or
plastic soled shoes nowadays and floors are nearly always covered with
a layer of material which is afairly good insulator.

It's only of your other hand is leaning on something earthy that one
gets a shock usually. I can't remember when (if ever) I've got a shock
which was anything other than hand to hand (bad, across chest) or,
more often in my case, simply across my fingers.


I did post a couple of years ago about this subject - ie what is the point
of earth bonding, but no-one could answer at the time. From recent posts I
can see what the reason is, but my point is that earth bonding protects
against one kind of fault only. I'm just giving an example where it made
the fault more dangerous.

It can only make things more dangerous if there's something conductive
at earth potential in the bathroom, if there is then the bonding is
faulty because that item should be connected too. If the bonding is
done correctly then even a damp floor will be at the same potential as
the bonded metalwork, where else can it get its voltage level from?

--
Chris Green

Dave Plowman wrote:
In article ,
Christian McArdle wrote:
What sort of bathroom floor has enough conductivity to give you a
powerful enough shock to kill you? Typically, a bathroom floor will be
timber, plastic, stone or ceramic. All are excellent insulators and will
not support the levels of current needed for a dangerous current flow.

I'd not fancy my chances of standing barefoot on a wet concrete floor and
touching a 240 supply with wet hands. You try it if you want. ;-)

How many bathrooms have bare concrete floors? Even then if the
bonded metalwork is at 240 volts it's odds on that the floor will be
too.

--
Chris Green

I'd not fancy my chances of standing barefoot on a wet concrete floor and
touching a 240 supply with wet hands. You try it if you want. ;-)

Urgh! You have a wet concrete floor in your bathroom?

Besides, what do you think the conductivity is of set unreinforced concrete
with surface water?

Christian.

On 28 Jan 2004 14:50:30 GMT, wrote:

Lurch wrote:

I didn't say connect it directly, I said it is connected by default,
i.e. all earths connected together at the CU. More than likely the
earth path from supplementary bonded metalwork will end up connected
here.

But the whole point is that "supplementary bonding" *isn't* an earth
connection and doesn't work by being connected to earth.

I know.

It may well be that in many installations (e.g. where all pipework is
copper) the supplementary bonded metalwork in the bathroom is
connected to earth but that isn't what makes it useful.

It works by bringing all simutaneously touchable exposed pieces of
metalwork to the same potential, (not neccesarily 0v though). See, I
do know.
In 'most' cases it would be connected to earth, fine, I'm not
disagreeing.


SJW
A.C.S. Ltd.

On Wed, 28 Jan 2004 13:36:41 +0000 (GMT), Dave Plowman
wrote:

In article ,
wrote:
Not quite sure they go that far; certainly with plastic plumbing there is
less that needs bonding, e.g. taps don't; but other electrical gear
such as electric showers, heaters, shaver points, etc. will still need
cross-bonding.

Do you really need to cross-bond a shaver socket given that the only
exposed metalwork is the fixing screws?

Which, if they are like normal socket outlets, are earthed anyway...

--
How do they get teflon to stick to the pans?

Mail john rather than nospam...