Stephen wrote:
On Sun, 04 Jan 2009 21:12:29 +0000, John Rumm
wrote:

Where is the boiler? Where was it in the last place?

Generally speaking you would expect to see supplementary equipotential
bonding in places that pose an special risk (bath / shower rooms, pool /
saunas etc). There is no harm in have supplementary bonding between its
connections, however there is in many cases no absolute requirement for
it. Note that supplementary bonds do not need to be either earthed, or
connected back to the main CU earth terminal.

It is in the kitchen, exactly where the old one was. Thinking about it
it's all copper pipe around the boiler but after 2 metres it turns
plastic, so I'm not sure that bonding would do much, except in the
immediate area of the boiler.

In "special locations" (of which a kitchen is *not* one - part P lumps
it in with them, but the wiring regs do not), the question to ask, is
are the pipes capable of introducing a potential into the room from
elsewhere. In you case it sounds like the answer is "no".

To quote the OSG (16th edtn): "There is no specific requirement in BS
7671 to supplementary bond the following

kitchen pipes, sinks or draining boards

metal furniture in kitchens

metal pipes and wash hand basins in domestic locations
other than bathrooms."

Is supplemental bonding supposed to be 10mm^2 too? I am not going to
do it (unless you tell me otherwise) but I ask out of curiosity.

Where there is no mechanical protection for the bonding conductors,
4.0mm is commonly used. Where you are bonding a circuit protective
conductor, then you should not use a smaller CSA wire than that of the
CPC - however domestic wires with CPCs larger than 4.0mm are not common
(only 16mm^2 for T&E)

--
Cheers,

John.

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