I have to do a bit of pipework (15 mm copper) in my house which was build in
around 1980-1982. Because of the location I'd like to use Cuprofit fittings
in a couple of places. Having looked at the Cuprofit specs
(http://www.britishmetrics.com/pdf/tech.pdf) I note that they do not
maintain earth continuity. How can I tell if my pipework is supposed to be
earth bonded?

Incidentally, OE's spellchecker doesn't like 'Cuprofit' and suggests
'coprolite', i.e. fossilised ****. Is this a warning to me? ;-)

Ta muchly,

Steve S

--
Put both the cats out before replying.

SteveS wrote:

Incidentally, OE's spellchecker doesn't like 'Cuprofit' and suggests
'coprolite', i.e. fossilised ****. Is this a warning to me? ;-)

Yes, it is a warning. Abandon OE as soon as possible.

As for the Cuprofit, I've used them, and they are nice fittings. But I
have had one leak. I've never had a Speedfit or a Hep fitting leak. I
never worked out why it leaked. The O ring looked fine, the pipe was in
far enough.

I'm not saying don't use them - I'll be using them again. Just make sure
you pressure test everything before making the pipework inaccessible.


--
Grunff

Having looked at the Cuprofit specs
(http://www.britishmetrics.com/pdf/tech.pdf)
I note that they do not maintain earth continuity. How can I tell if my
pipework
is supposed to be earth bonded?

Well, you might not need to bother earth bonding. If you do, then it is
easily achieved with 2 earth clamps and a bit of suitably rated earth cable.
Personally, I'd be inclined not to, on the "isolation is safer than earthing
principle", especially if RCDs are installed.

However, I would still supplementary bond in a bathroom where required, as
the isolation provided would be insufficient to assure the local
equipotential zone.

Christian.

"Christian McArdle" wrote in message
et...


However, I would still supplementary bond in a bathroom where required, as
the isolation provided would be insufficient to assure the local
equipotential zone.


Thanks for the advice.

Yes, the bathroom is involved, so I'll bond. I presume I'll need 10mm earth
wire?

Cheers,

Steve S

Yes, the bathroom is involved, so I'll bond. I presume I'll need 10mm
earth
wire?

For supplementary bonding, I'd only bridge the Cuprofit if it is installed
inside the bathroom. Otherwise, just supplementary bond the section within
the bathroom to all other fittings that require it, but leave the external
Cuprofit unbridged. Ideally (which is not possible if there are electrical
fittings or other continuous earthed services) the supplementary bonded
metalwork in the bathroom will be connected to each other, but not earth.
This makes everything in the bathroom at the same voltage, but without
providing a low impedence path to earth. Of course, it is rarely possible to
achieve without plastic plumbing.

Christian.

On Fri, 23 Jul 2004 16:08:12 +0100, "Christian McArdle"
wrote:

Yes, the bathroom is involved, so I'll bond. I presume I'll need 10mm
earth
wire?

For supplementary bonding, I'd only bridge the Cuprofit if it is installed
inside the bathroom. Otherwise, just supplementary bond the section within
the bathroom to all other fittings that require it, but leave the external
Cuprofit unbridged. Ideally (which is not possible if there are electrical
fittings or other continuous earthed services) the supplementary bonded
metalwork in the bathroom will be connected to each other, but not earth.
This makes everything in the bathroom at the same voltage, but without
providing a low impedence path to earth. Of course, it is rarely possible to
achieve without plastic plumbing.

Christian.

Errrr... I must be missing something here. What is the point of connecting all
the bits of metal together but not to earth? This doesn't "make everything in
the bathroom at the same voltage". It just makes them all 'floating', just the
same as if you leave them individually 'floating'.

Tom B wrote:
On Fri, 23 Jul 2004 16:08:12 +0100, "Christian McArdle"
wrote:

Yes, the bathroom is involved, so I'll bond. I presume I'll need 10mm
earth
wire?

For supplementary bonding, I'd only bridge the Cuprofit if it is installed
inside the bathroom. Otherwise, just supplementary bond the section within
the bathroom to all other fittings that require it, but leave the external
Cuprofit unbridged. Ideally (which is not possible if there are electrical
fittings or other continuous earthed services) the supplementary bonded
metalwork in the bathroom will be connected to each other, but not earth.
This makes everything in the bathroom at the same voltage, but without
providing a low impedence path to earth. Of course, it is rarely possible to
achieve without plastic plumbing.

Christian.

Errrr... I must be missing something here. What is the point of connecting all
the bits of metal together but not to earth? This doesn't "make everything in
the bathroom at the same voltage". It just makes them all 'floating', just the
same as if you leave them individually 'floating'.

If all the metalwork/water is at the same potential, then there is no
possibility of getting across two individual appliances, one of which
has a fault, causing it to be live.

Then again...

On Fri, 23 Jul 2004 17:56:18 +0000 (UTC), Tom B wrote:

Errrr... I must be missing something here. What is the point of
connecting all the bits of metal together but not to earth? This
doesn't "make everything in the bathroom at the same voltage".

Yes it does, how can they be at (significantly) different voltages
when connected by 10mm^2...

It just makes them all 'floating', just the same as if you leave
them individually 'floating'.

The important thing is that they all float together. If they aren't
bonded then your bath taps could be at one voltage and the radiator
another.

--
Cheers
Dave. pam is missing e-mail

On Fri, 23 Jul 2004 17:56:18 +0000 (UTC), Tom B
strung together this:

Errrr... I must be missing something here. What is the point of connecting all
the bits of metal together but not to earth? This doesn't "make everything in
the bathroom at the same voltage". It just makes them all 'floating', just the
same as if you leave them individually 'floating'.

By cross-bonding everything you are holding them all at the *same *
floating potential. If you don't cross-bond them then they are at
*different* floating potentials.
--

SJW
A.C.S. Ltd

On 23 Jul 2004 18:47:04 GMT, Ian Stirling wrote:

Tom B wrote:
On Fri, 23 Jul 2004 16:08:12 +0100, "Christian McArdle"
wrote:

Yes, the bathroom is involved, so I'll bond. I presume I'll need 10mm
earth
wire?

For supplementary bonding, I'd only bridge the Cuprofit if it is installed
inside the bathroom. Otherwise, just supplementary bond the section within
the bathroom to all other fittings that require it, but leave the external
Cuprofit unbridged. Ideally (which is not possible if there are electrical
fittings or other continuous earthed services) the supplementary bonded
metalwork in the bathroom will be connected to each other, but not earth.
This makes everything in the bathroom at the same voltage, but without
providing a low impedence path to earth. Of course, it is rarely possible to
achieve without plastic plumbing.

Christian.

Errrr... I must be missing something here. What is the point of connecting all
the bits of metal together but not to earth? This doesn't "make everything in
the bathroom at the same voltage". It just makes them all 'floating', just the
same as if you leave them individually 'floating'.

If all the metalwork/water is at the same potential, then there is no
possibility of getting across two individual appliances, one of which
has a fault, causing it to be live.

Then again...

No, No, No... If all the metalwork/water is at the same potential then there is
no fault and therefore no problem! :-)

If an appliance earth fails AND the case becomes live then touching it while
touching another good earth is likely to give you 50 cycle flutter of the
eyeballs. Earthing lots of otherwise 'floating' bits of metal in the vicinity is
more like to enable this to happen rather than less.

On Fri, 23 Jul 2004 21:24:13 +0100, Lurch
wrote:

On Fri, 23 Jul 2004 17:56:18 +0000 (UTC), Tom B
strung together this:

Errrr... I must be missing something here. What is the point of connecting all
the bits of metal together but not to earth? This doesn't "make everything in
the bathroom at the same voltage". It just makes them all 'floating', just the
same as if you leave them individually 'floating'.

By cross-bonding everything you are holding them all at the *same *
floating potential. If you don't cross-bond them then they are at
*different* floating potentials.

If they are floating there is no source (or sink) of current to do any damage.

In article om, Dave
Liquorice wrote:

The important thing is that they all float together. If they aren't
bonded then your bath taps could be at one voltage and the radiator
another.

Although he house I've recently bought has the gas and water bonded and
earthed at the point of entry there's no bonding in the bathroom. It
will be quite straightforward to bond the washbasin taps and radiator
together. Bonding the hot and cold bath taps together will be no problem
but making a direct connection between these and the washbasin would be
an untidy and tedious job. The positioning of the basin and bath is such
that only a suicidal contortionist would be likely to touch the taps on
both at the same time, do I really need to join the two groups?

I'm also wondering if I need to bond the supply pipe to the toilet
cistern, it comes out of the wall a couple of inches below the cistern
and goes straight into the bottom of it and is well out of reach of any
other pipework?

I've checked the resistance of all exposed pipework to earth and it's
all less than 1 ohm.
--
Mike Clarke

"Tom B" wrote in message
...
On Fri, 23 Jul 2004 21:24:13 +0100, Lurch
wrote:

On Fri, 23 Jul 2004 17:56:18 +0000 (UTC), Tom B
strung together this:

Errrr... I must be missing something here. What is the point of
connecting all
the bits of metal together but not to earth? This doesn't "make
everything in
the bathroom at the same voltage". It just makes them all 'floating',
just the
same as if you leave them individually 'floating'.

By cross-bonding everything you are holding them all at the *same *
floating potential. If you don't cross-bond them then they are at
*different* floating potentials.

If they are floating there is no source (or sink) of current to do any
damage.


Current source and current sink are two entirely different things - and have
nothing to do with the subject under discussion.

On Sat, 24 Jul 2004 09:22:40 +0000 (UTC), Tom B
strung together this:

If they are floating there is no source (or sink) of current to do any damage.

Under normal circumstances yes, but anything can happen under fault
conditions.
Look Tom, don't argue with me over it, I don't really care if anyone
bonds bathroom pipework together or not, I don't make the rules. Try
firing some emails off to the IEE and ask them why they decided pipes
need bonding, I don't give a **** to be quite honest.
--

SJW
A.C.S. Ltd

I've checked the resistance of all exposed pipework to earth and it's
all less than 1 ohm.

Look at it this way, are the electric police going to come and break your
door dowen at 2 in the morning because you did'nt cross bond in the
bathroom ?

Dave

--

Some people use windows, others have a life.

On Sat, 24 Jul 2004 09:22:40 +0000 (UTC), Tom B wrote:

If they are floating there is no source (or sink) of current to do
any damage.

"It's volts that jolts, mils that kills."

We are talking moderately high impedances here, 7.5k at 230v PD allows
30mA to flow. Wet floor, wet hands I wouldn't like to pick up anything
live.

--
Cheers
Dave. pam is missing e-mail

On Sat, 24 Jul 2004 11:16:19 +0100, Mike Clarke wrote:

do I really need to join the two groups?

Only if you want to. The regs are essentially for new installations or
ones that are worked on(?). Everyone doesn't have to go out bonding
things beacuse the regs changed however many moons ago it was.

--
Cheers
Dave. pam is missing e-mail

On Sat, 24 Jul 2004 12:33:03 +0100, "Farmer Giles" wrote:


"Tom B" wrote in message
.. .
On Fri, 23 Jul 2004 21:24:13 +0100, Lurch
wrote:

On Fri, 23 Jul 2004 17:56:18 +0000 (UTC), Tom B
strung together this:

Errrr... I must be missing something here. What is the point of
connecting all
the bits of metal together but not to earth? This doesn't "make
everything in
the bathroom at the same voltage". It just makes them all 'floating',
just the
same as if you leave them individually 'floating'.

By cross-bonding everything you are holding them all at the *same *
floating potential. If you don't cross-bond them then they are at
*different* floating potentials.
How come?

If they are floating there is no source (or sink) of current to do any
damage.


Current source and current sink are two entirely different things - and have
nothing to do with the subject under discussion.

Errr... best stick to the farming :-)


Let me try one last time to explain my point:

Voltage on its own is not dangerous - think of birds sitting on the 22kV power
line. Wearing suitably insulated shoes, and with one hand in your pocket, you
can touch a live point without getting a lethal shock .
If you then with the other hand touch a piece of metal that is not electrically
connected to anything else ('floating') then again you are still quite safe. (Ok
you pedants out there, there may be a very small leakage current, I'm trying to
keep this simple).

However, if you now earth the piece of metal and repeat the exercise you are
very likely to die. (Assume no RCDs here, only 30A fuses)

You can not of course get a lethal shock by touching two separate isolated
pieces of metal. The key word here is 'isolated'.

In other words in some circumstances it can be more dangerous to bond than
not. . I think others were making the same point.

"Tom B" wrote in message
...
On Sat, 24 Jul 2004 12:33:03 +0100, "Farmer Giles" wrote:


"Tom B" wrote in message
.. .
On Fri, 23 Jul 2004 21:24:13 +0100, Lurch

wrote:

On Fri, 23 Jul 2004 17:56:18 +0000 (UTC), Tom B
strung together this:

Errrr... I must be missing something here. What is the point of
connecting all
the bits of metal together but not to earth? This doesn't "make
everything in
the bathroom at the same voltage". It just makes them all
'floating',
just the
same as if you leave them individually 'floating'.

By cross-bonding everything you are holding them all at the *same *
floating potential. If you don't cross-bond them then they are at
*different* floating potentials.
How come?

If they are floating there is no source (or sink) of current to do any
damage.


Current source and current sink are two entirely different things - and
have
nothing to do with the subject under discussion.

Errr... best stick to the farming :-)

Actually I am a graduate electrical engineer with over 30 years experience -
it is you who clearly do not know what you are talkinf about.




Let me try one last time to explain my point:

Voltage on its own is not dangerous - think of birds sitting on the 22kV
power
line. Wearing suitably insulated shoes, and with one hand in your
pocket, you
can touch a live point without getting a lethal shock .
If you then with the other hand touch a piece of metal that is not
electrically
connected to anything else ('floating') then again you are still quite
safe. (Ok
you pedants out there, there may be a very small leakage current, I'm
trying to
keep this simple).

However, if you now earth the piece of metal and repeat the exercise you
are
very likely to die. (Assume no RCDs here, only 30A fuses)

You can not of course get a lethal shock by touching two separate isolated
pieces of metal. The key word here is 'isolated'.

In other words in some circumstances it can be more dangerous to bond
than
not. . I think others were making the same point.

The point you are making is about potential difference. The point you
introduced about source and sink current has nothing to do with it. If all
metalwork is cross-bonded then you create an equipotential zone and no PD
can occur - and therefore no current can flow.

In article om, Dave
Liquorice wrote:

On Sat, 24 Jul 2004 11:16:19 +0100, Mike Clarke wrote:

do I really need to join the two groups?

Only if you want to. The regs are essentially for new installations or
ones that are worked on(?). Everyone doesn't have to go out bonding
things beacuse the regs changed however many moons ago it was.

The house was apparently rewired only a few years ago so I expect it
ought have been bonded at that stage in order to comply. With good earth
continuity and RCD protection I don't think the lack of bonding puts us
at serious risk. It would need a bizarre combination of faults to
produce a significant PD between hot and cold taps without tripping the
RCD. OTOH I feel that it wouldn't harm to get as close to the regs as
reasonably possible.

I was also wondering if it's considered good practice (as opposed to a
regulatory decree) to bond all pipework at the boiler. I suspect there's
some plastic pipework in the cold supply leading to it under the floor,
if this is so then the central heating and hot water pipework are
effectively earthed via the boiler's earth. I'm thinking here in terms
of protecting against a major fault in the boiler combined with the loss
of it's earth connection.

Or am I just being too paranoid?

--
Mike Clarke