Owain wrote:

At 30m you will have to do proper calculations to prove the cable size is
suitable taking into accoutn voltage drop and fault impedance etc

This will get you started:-

http://www.tlc-direct.co.uk/Technica...ltageDrop.html

(SWA is typically XLPE these days)

At thirty meters I would be more inclined to not export the house earth
(i.e. use it to earth the screen of a two core cable, but terminate that
in a insulated consumer unit at the far end. Then use a local earth rod
with local 30mA trip RCD to provide a TT setup. You will also need to
consider protection for the cable at the source end in the event of a
catastrophic L to N or L to E fault in the cable.

--
Cheers,

John.

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