On 27/08/2019 22:53, Theo wrote:

I'm speccing up installing sockets in a brick garage. It currently has a CU
with an adjacent pair of double sockets on a short radial. I want to put some
sockets at various points around the far sides.

Approx how many sockets in total?

What do you anticipate running from them?

(i.e. do you need the extra power available from a 32A ring rather than
a 16 or 20A radial)

(and for the pedants, yes you could run a 32A radial in 4mm^2, and spur
each socket in 2.5mm^2(

Because of the construction of the garage, it would be easiest to run the
wiring at head height, and run down trunking to the places where sockets are
wanted. There are roughly two options:

Have you considered dado trunking?

1. A radial around three sides, with the sockets on essentially long loops
down from the ceiling. This is just an extension of the existing radial.

You can do that - or the backbone and branch style with spurs from the
radial.

2. A ring main around at ceiling level. The simplest way would be for each
socket to be spurred off, but I understand spurs aren't well received.

In a conventionally wired ring its usually better to start with few
spurs, however its equally valid to take a design decision to use spurs
exclusively if it makes more sense.

An
alternative would be to use a variation of 1) where the ring takes a long
loop down to each socket

Tis probably what I would do, or, drop down to the first socket on the
wall, then run horizontally between them, and back up to the ceiling at
the last one.

Also, Part P wise, am I right in thinking that extending a radial is OK but
converting a radial to a ring is notifiable?

No. Adding a whole new circuit would be notifiable (if anyone actually
cared!) Extending one is ok, and arguably still ok if the extension
takes it back to the CU.

Finally, is it acceptable to cable-clip T&E cables (bearing in mind the new
rule to use metal clips occasionally) in an outbuilding, or is additional
protection (trunking) needed (even at ceiling level)?

Depends on what you are doing in there, and what the likely risk of
mechanical damage is.




--
Cheers,

John.

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