this may be of some help
http://www.niceic.org.uk/downloads/P...0Guide%202.pdf you need to
connect all earth terminals in the zones together along with metal pipe
work, metal bath and any radiator fed with metal pipes, dont run cable back
to mains, this isnt about introducing earth potential but creating a
faradays cage so all metal work will be at same potential. If your in
England this is under part p of building regs and is a legal requirement to
notify the local authority so is swapping a shower in a bathroom.....is your
cable and pull switch up to the job (current) of the new shower?

"John Rumm" wrote in message
...
Stuart wrote:

About 12 years ago when I installed my electric shower I did all the
plumbing
and cabling and got Scottish power ( It was SSEB then ) to do the final
connection .The guy came and did the job but commented to add an
additonal earth
cable from the shower to the CH radiator and then back to the Scottish
Power
earth terminal beside the consumer unit . This I did and it has remained
that
way ever since .

I have just replaced my shower with a 10.5 one and was unable to get the
circuit
earth and this extra earth cable in to the cable connector ( The previous
shower
had a stud and nut connection arrangement ) so I have left out the
additional
earth between the earth and the radiator . It set me thinking why this
extra
earth was necessary in the first place and also about the earth from the
radiator as well.

The short answer is that it wasn't.

Should I leave things as they were before ( Using thinner
earth cable betweeen shower and radiator to allow it to get in to the
connector)
or what does anyone suggest ?

You need to ensure that the equipotential bonding in the room is present,
however there is no need for a discrete connection back to the CUs main
earth terminal (although since you would usually include the CPCs (i.e.
earth wires) of any circuits delivering power into the bathroom in the
equipotential bonding then you will in effect get this via a fortuitous
route)

--
Cheers,

John.

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