"Christian McArdle" wrote in message
t...
Is there a specification or a general rule as to how far away an
outbuilding can be before it requires it's own local earthing
arrangement? I've looked through past posts but couldn't find
such a figure mentioned.

As I understand it, you'll have to ensure the earth loop impedence is
within
spec, which gets increasingly difficult with longer cable runs and
increased
power. Also, you have to run main equipotential bonding back to the
earthing
terminal by the consumer unit in UNBROKEN thick earthing cable. This is an
issue if you have metallic services, or structural metalwork.

Christian.



OK, so reading into this answer, it will depend upon the expected usage in
the outbuilding along with the construction. For instance, for a supply to
a wooden shed that has outlets used for portable power tools it may be
acceptable to export the house earth, but if there's structural metalwork,
and fixed machinery (eg tablesaws) then a separate earthing arrangement
would be the only acceptable solution?

In my case, it's a wooden shed about 12m from the house, with portable power
tools being used in it...

For the equipotential bonding issue your answer implies that the SWA would
have to be run right back to the CU and terminated there, rather than at the
point of entry into the house, or are we talking about a bonding earth cable
completely separate to the SWA sheathing here?


thanks
Richard

--
Richard Sampson

email me at
richard at olifant d-ot co do-t uk