In message om,
"Dave Liquorice" wrote:

On Tue, 28 Jun 2005 17:18:28 GMT, Lobster wrote:

I now make the score three-two in favour of the 'Yes' camp...
Where do I go for a definitive answer? My newly-expert BCO? ;-)

The Onsite Guide only has note in te various diagrams which says:

"Main equipotential bonding conductors maybe seperate (as shown) or
looped with unbroken conductors"

The "(as shown)" refers to seperate conductors from the main earth
terminal to metal services pipes. The "looped with unbroken
conductors" implies that broken conductors between the main earth
terminal and the metal service pipe is not allowed. Therefore it ought
to be a single length of cable.


The problem is that neither BS7671 nor the OSG is specific on this
matter. There is no paragraph in either (AFAICS) which categorically
states "main EP bonding conductors must be unbroken between the main
earthing terminal and the connection point to the service pipe". The
phrase quoted is the closest you get to that, and IMO specifically
refers to the situation where there is one wire which runs from the main
earthing terminal first to one service and then to another. It is an
annotation to an example diagram and isn't referred to in the text of
the OSG, and doesn't refer to a paragraph number in BS7671.

It is *probably* meant to guard against the situation where the
connection to the first service becomes loose. Where two wires are run,
the second service will still be connected and since the services (e.g.
gas & water) are usually connected metalically somewhere, a measure of
bonding still applies. If there is just one cable, and it is broken
(i.e. two lengths were used) at the first service, the connection to the
second may also be lost. A single length of cable will not suffer here.

Having said that, I have always run single continuous lengths for the
main bond, and have never jointed. I would consider a joint where
replacing the whole run would be impractical, but impractical does not
include "the run is 15m and I've only 12m of cable left on the drum".

Hwyl!

M.

--
Martin Angove: http://www.tridwr.demon.co.uk/
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