First of all do I need to, I presume so ?

If I need to as I suspect, whats the best practise? Is it acceptable/best to
cross bond the copper pipe back to the existing bonded pipework, or back to
an earth connection at the back of a socket ?


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In message ,
"Justin" jsheldon@ remove me lineone.net wrote:

First of all do I need to, I presume so ?

If I need to as I suspect, whats the best practise? Is it acceptable/best to
cross bond the copper pipe back to the existing bonded pipework, or back to
an earth connection at the back of a socket ?



As I understand it, everything in the bathroom needs to be bonded to
everything else. In other words, the CPC (earth wire) terminal inside
the shower is bonded to the cold pipe entering the shower, which is
bonded to the bath and basin taps (hot and cold - yes cold again to
account for dodgy joints or valves in the way) which are bonded to the
metalwork of a metal bath which is bonded to any radiator and/or heating
pipework which is bonded to the CPC in any shaver outlet (even though it
is double insulated), which is bonded to the CPC in any fan and which
may also need to be bonded to the CPC of the light and indeed
*anything* else metal which may be "earthy".

The one thing which isn't neccessary is to run the bond back to the main
earth terminal in / near the consumer unit!

HTH

Hwyl!

M.

--
Martin Angove: http://www.tridwr.demon.co.uk/
Two free issues: http://www.livtech.co.uk/ Living With Technology
.... Copywight 1994 Elmer Fudd. All wights wesewved

The one thing which isn't neccessary is to run the bond back to the main
earth terminal in / near the consumer unit!

But your pipe work must be bonded to earth from your main earth block as near
to as possible where it enters your property and then cross bonded in bathroom
and tested for continuity back to source.

The pump is in the airing cupboard upstairs. The hot pipe to the HWC is
bonded, so should the other copper pipes?


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In message ,
(Wheelbarrowbob) wrote:


The one thing which isn't neccessary is to run the bond back to the main
earth terminal in / near the consumer unit!

But your pipe work must be bonded to earth from your main earth block as near
to as possible where it enters your property and then cross bonded in bathroom
and tested for continuity back to source.

Yes, the incoming water (and gas and oil) pipework must be bonded to the
main earth, on the consumer's side, within 600mm (IIRC) of the meter or
stop valve and before any branch pipework, but I can't recall any
requirement to test that there is continuity between *supplementary*
bonded metalwork in the bathroom and the main earth.

The point of supplementary bonding is *not* to make sure all metalwork
stays at earth potential, rather it is to ensure that it all stays at
the *same* potential, whatever that may be. The slightly dubious safety
reasoning behind this is that if there is an earth fault in (say) your
shower, this may cause the touchable metal parts of the unit
("exposed conductive parts") (not that modern showers have any) to rise
above earth potential. By cross bonding these metal parts to other metal
parts ("extraneous conductive parts" e.g. the taps) with which you may
be in contact, in theory no current will flow (through you) as
everything is at the same potential. Hopefully, of course, current
*will* be flowing down the CPC in the shower supply cable and will pretty
rapidly switch off the supply.

If you provide an explicit link from the supplementary bonding straight
back to the main earth, this link could quite easily be of lower
resistance than the CPCs involved (supp. bonding is usually in 4mm2
cable, CPCs of 6mm2 shower cables are 2.5mm2 and of lighting cables,
1mm2) and therefore anything thus bonded *could* be at a lower potential
than the cause of the fault... and the fault current will flow through
the bonding rather than the CPC which is where it should be flowing.
Of course if everything is hunky-dory this is highly unlikely.

Hwyl!

M.

--
Martin Angove: http://www.tridwr.demon.co.uk/
Two free issues: http://www.livtech.co.uk/ Living With Technology
.... Plasma is another matter.

could* be at a lower potential
than the cause of the fault... and the fault current will flow through
the bonding rather than the CPC

Assuming that no one has at some time put plastic push fit connectors into the
plumbing system . This would cause a fault current to find another way to earth
other than via the bonded metalwork and or possibly the cpc. There may not be
a requirment to test for continuity but it makes sense to when messing with
power showers and water that was my point really.

On Tue, 02 Mar 2004 01:20:31 GMT, in uk.d-i-y Martin Angove
strung together this:

Yes, the incoming water (and gas and oil) pipework must be bonded to the
main earth, on the consumer's side, within 600mm (IIRC) of the meter or
stop valve and before any branch pipework, but I can't recall any
requirement to test that there is continuity between *supplementary*
bonded metalwork in the bathroom and the main earth.

The point of supplementary bonding is *not* to make sure all metalwork
stays at earth potential, rather it is to ensure that it all stays at
the *same* potential, whatever that may be. The slightly dubious safety
reasoning behind this is that if there is an earth fault in (say) your
shower, this may cause the touchable metal parts of the unit
("exposed conductive parts") (not that modern showers have any) to rise
above earth potential. By cross bonding these metal parts to other metal
parts ("extraneous conductive parts" e.g. the taps) with which you may
be in contact, in theory no current will flow (through you) as
everything is at the same potential. Hopefully, of course, current
*will* be flowing down the CPC in the shower supply cable and will pretty
rapidly switch off the supply.

If you provide an explicit link from the supplementary bonding straight
back to the main earth, this link could quite easily be of lower
resistance than the CPCs involved (supp. bonding is usually in 4mm2
cable, CPCs of 6mm2 shower cables are 2.5mm2 and of lighting cables,
1mm2) and therefore anything thus bonded *could* be at a lower potential
than the cause of the fault... and the fault current will flow through
the bonding rather than the CPC which is where it should be flowing.
Of course if everything is hunky-dory this is highly unlikely.

But as you say, the point of the supplementary bonding is to make all
the exposed metalwork in the bathroom the same potential. If this was
linked to the main earth termminal then the metalwork would still be
at the same potential, just lower.
...

SJW
A.C.S. Ltd.

There may not be a requirment to test for continuity but it makes
sense to when messing with power showers and water that was my
point really.

It is actually safer without any continuity to the main earthing terminal.
It is just not normally possible to achieve.

The ideal situation is that all supplies are plastic and there are no
electrics. Then you don't need supplementary bonding at all, even with metal
baths and radiators.

Christian.