I rather like the idea of having a bespoke medium current isolated supply as
well, which will enable earthing of the neutral so 'live' chassis devices
and can be safely worked on. I used to do this many years ago, but fear
doing this now could easily result in a problem if something earthed to
mains earth from the house also gets earthed to my isolated neutral via the
transformer.

Nobody seemed to care in the 1970s!
Brian

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"David Wade" wrote in message
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On 13/08/2019 18:30, Arthur Ravenscroft wrote:
Hi.
Just thinking on while I'm rewiring the kitchen I may as well lay down
the cable to reach the shed in the back yard.
I used 10m of 6mm cable to reach the cooker connection unit so I'll need
only 20m maximum to reach a box in my shed.

1st question : It will be a separate breaker in the CU so white size
cable to use 6, 4 or 2.5 ?

Thanks.

Arthur
If possible e-arrange your consumer unit so that the shed is fed from an
RCBO that is not connected to any existing RCD device in the consumer
unit. If thats not possible get a new consumer unit.

That way when you get water in the shed electricsit won't trip the RCD and
take out whatever else is connected to that RCD.

I leave it to others to cover the rules on sheds, part p, sheathed cable,
catenaries, exported earths etc.

Dave