Am I correct in thinking that if I have a TT circuit feeding the shed, the lighting as well as the sockets ought to be fed via an RCD?
I'm just about to change the feed from the house. At present the shed is fed from a radial circuit from the PME CU in the house.
TIA -
Yes, everything. TT relies heavily on RCD or ELCB for its earth protection to work. For this reason I'm not sure if you'll improve things any by going TT. Even a long 1mm^2 exported earth will have much lower impedance than any TT earth. Though exporting earths is not issue free.
Where power tools are used its important to have sockets and lights on diffrent rcds.
NT
Thanks. One of the reasons for the change is that I intend (at a later date) to extend even further from the shed, to a pump and UV filter at the end of the garden. The existing pump is 24V.
Cheers -
On Sat, 18 Nov 2006 13:47:02 +0000 someone who may be Frank Erskine wrote this:-
The issues of earthing supplies in the garden are covered by the IET article that a search engine will pull up. Distance from the house is a factor in these considerations.
Even if its 100m your exported earth is going to be an order or 2 of magnitude better performer than a local rod.
NT
but 100m away it's not going to be the "same" earth is it?
Owain
It isn't the impedence that is the issue with long exported earths, it is just that the earths could have several volts (or more) difference.
It might be considered better to have a poor local earth to a good remote one, provided the switchgear is still able to break an earth fault (i.e. through using an RCD).
Christian.
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