"Paul" wrote in message
om...
Hi,
snipped
My questions are (sorry there are a lot of them) :
1. I'm going to use a spare 20Amp 'B' type MCB on the non-RCD
protected side of the CU using 4mm T+E cable. Can I use normal T+E
cable for the first 8m (up to the outside of the house) and then
connect it using a junction box, to 8m of SWA 4mm cable to the shed?
Any external wiring should be protected as much as possible, so I'd personally
advise you to use the RCD side of the CU.
It's also best and safest if you can make the SWA in a single run all the way
between the two points. Joints in anything, by nature, make them less
efficient. And I'd also go for 6 mm csa' SWA on that full length to make sure
that supply is adequate enough to take any fault currents.
2. I was planning to place the RCD spur unit inside the shed at the
end of the SWA cable. Can I then continue the radial circuit using
normal 4mm T+E or could I use a Fused Connection Unit after the RCD
and continue with 2.5mm T+E?
The circuits you intend to install from the shed supply are not going to be huge
loads, so 2.5 mm csa' should be enough for radial connection to them.
You might also find that you need to install quite a large, not huge, junction
box inside the shed to take all the seperate circuit connections you want to
make. Not just now, but in the future.
3. Can I use a plastic back box for the double socket or are there
special 'shed' style sockets?
Try to go for industrial socket plates and light fittings because they are
slightly safer for outdoor use. They also take more of a bashing in extreme
weather conditions. Weather proof is even better for building that are not
going to be at constant temperature and humidities.
4. I have estimated a total of 10m of cable being used inside the
shed. Does this have any impact of whether I should use a separate
earth rod or can I just connect the power to the house earth?
Relying on the Wire Armour is never a good thing really. So I'd advise that a
seperate local spike be driven. You should then be using a separate CU in the
shed and make your individual circuits from that.
Just so you know, I was going to spur to use a 5amp FCU for the shed
light and the security light. Also, all the outside cabling is SWA and
will be in that 20mm blue plastic piping that you can buy from Wickes,
buried deep deep underground.
Thank you in advance!
Paul
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