On Mon, 02 Apr 2007 21:44:27 GMT, "pls" mused:

I need to install an external socket and a few garden lights (mixture of LV
LEDs and GU10 halogen fittings) in my garden (approx 5m from the house) and
have a few questions:

1.) For one of the cable runs in the garden I will need to run 3 separately
switched circuits for the deck LEDs, pond pump and step lights (LED).It will
need to run underground so I was thinking of using polypropylene conduit
(http://www.toolstation.com/index.html?code=20536) with 3 lengths of single
core conduit cable for each of the switched live circuits. If I bury at the
recommended depth (450mm) and cover with slabs, presumably this will offer
comparable mechanical protection to SWA as interpreted by the regs? The
neutral and earth I would run separately (probably in some left over 2 core
SWA)

I''d run a couple or 3 SWA cables out, or a 7 core SWA.

2.) I need to work out how to power the external socket/lights from the
house. The easiest option is to run a spur off the ground floor ring (using
a 13A RCD FCU -
http://www.screwfix.com/app/sfd/cat/...14770&ts=48780) and then from
that a branch with a 3A FCU for the external lights.
Looking at the Collins DIY interpretation of the wiring regs they seem to
state that if an external power socket (or light for that matter) is NOT
located on the external wall of the house then it has to be run in a
separate (RCD protected) circuit direct from the CU. This seems overkill for
one outdoor socket and a few lights, and wonder if they are talking about
power to an external outbuilding (where potentially the loads would be much
higher with separate ring circuits etc)

Coming off the socket circuit via an RCD spur is fine. Even if your
sockets are already protected by an RCD then the additional RCD spur
will hopefully provide some descrapncy.

3.) As part of the lighting, I will be installing three recessed ground
lights in the patio
(http://www.screwfix.com/app/sfd/cat/...04 2&ts=49971)
These come preinstalled with 1m of flex to a waterproof junction box which
will accept PVC flex. The instructions are rather vague about installation
in the ground, presumably the 1m flex will need mechanical protection since
the whole light is buried in the patio? I wanted to run SWA to each of the
fittings but they won't accept SWA so I was thinking of running the SWA to a
IP box on the wall and then run flex from there to the junction box (below
ground) if that is permissible? Again difficult to interpret from the regs.

I wouldn't use a junction box underground. If the provided flex is too
short replace it with a longer length and use flexible conduit for
some protection, but keep the runs from the lights to juncrtion boxes
as short as possible.
--
Regards,
Stuart.