Hello -

I'm about to install a 150W PIR security light on the upstairs ring main,
and I'm wondering what best practice is.

There's a single 13A socket in a convenient location with an apparently
secure steel backbox., but I'm concerned that if I try to drill a big hole
in the back of the backbox, it may become loose, generating more work, and
I'd lose a socket anyway.

What I'm thinking of doing is bringing the socket forward a bit by
installing a shallow surface box on top of the backbox, then running a short
piece of 2.5mm cable sideways across the surface to new surface box
containing the fused/switched connection unit, with a length of 1mm cable
running though the wall from the new surface box. Does this violate any
regulations or good practice?

In article ,
"Simon" writes:
Hello -

I'm about to install a 150W PIR security light on the upstairs ring main,
and I'm wondering what best practice is.

There's a single 13A socket in a convenient location with an apparently
secure steel backbox., but I'm concerned that if I try to drill a big hole
in the back of the backbox, it may become loose, generating more work, and
I'd lose a socket anyway.

The boxes are normally pre-punched with 20mm holes. There's usually
a few mm of the circumference which isn't punched. Drill that out
with a something like a 4mm metal drill, push a screwdriver through
the small hole (or use the rear of the drill bit) and bend it over
to ping out the centre.

What I'm thinking of doing is bringing the socket forward a bit by
installing a shallow surface box on top of the backbox, then running a short
piece of 2.5mm cable sideways across the surface to new surface box
containing the fused/switched connection unit, with a length of 1mm cable
running though the wall from the new surface box. Does this violate any
regulations or good practice?

That sounds fine.

I would sink another box next to the original. You need a 10mm gap
between the boxes with most common faceplate designs so they meet
with no gap.

With regard to the light, fit it as high as you can, so it can
cover the area by pointing downwards rather than out horizontally.
Avoid spilling light outside your boundary without asking the
owner of the adjacent property first, and avoid spilling light
out onto a highway where you may create a risk of dazzle.
After fitting, check with your neighbours that the light does
not disturb them. Normally the PIR needs to be separate from
the light, as their optimum positions are quite different, so
combined light/PIR units are best avoided -- you end up the the
light too low or the PIR too high.

--
Andrew Gabriel

Simon wrote:

I'm about to install a 150W PIR security light on the upstairs ring main,
and I'm wondering what best practice is.

There's a single 13A socket in a convenient location with an apparently
secure steel backbox., but I'm concerned that if I try to drill a big hole
in the back of the backbox, it may become loose, generating more work, and
I'd lose a socket anyway.

Metal back boxes usually have 20mm knock outs in them. Placing a
screwdriver on the edge of the knockout and tapping with a hammer is
usually enough to break it free. A quick wiggle with a pair of pointed
nosed pliers will usually free it.

Having said that, this is not going to help too much since you really
need to be able to fuse down for the lamp first.

What I'm thinking of doing is bringing the socket forward a bit by
installing a shallow surface box on top of the backbox, then running a short
piece of 2.5mm cable sideways across the surface to new surface box
containing the fused/switched connection unit, with a length of 1mm cable
running though the wall from the new surface box. Does this violate any
regulations or good practice?

It would be acceptable in the sense that you have added a fused spur to
power the light. You may find that you get a neater result if you were
to sink another backbox beside the socket for the FCU. Or you could
remove the existing socket box and widen the recess, then use a twin
single backbox (electrial wholesaler), that will take both the socket
and your FCU.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

In article , John
Rumm writes
Simon wrote:

I'm about to install a 150W PIR security light on the upstairs ring main,
and I'm wondering what best practice is.

There's a single 13A socket in a convenient location with an apparently
secure steel backbox., but I'm concerned that if I try to drill a big hole
in the back of the backbox, it may become loose, generating more work, and
I'd lose a socket anyway.

Metal back boxes usually have 20mm knock outs in them. Placing a
screwdriver on the edge of the knockout and tapping with a hammer is
usually enough to break it free. A quick wiggle with a pair of pointed
nosed pliers will usually free it.

Having said that, this is not going to help too much since you really
need to be able to fuse down for the lamp first.

What I'm thinking of doing is bringing the socket forward a bit by
installing a shallow surface box on top of the backbox, then running a short
piece of 2.5mm cable sideways across the surface to new surface box
containing the fused/switched connection unit, with a length of 1mm cable
running though the wall from the new surface box. Does this violate any
regulations or good practice?

It would be acceptable in the sense that you have added a fused spur to
power the light. You may find that you get a neater result if you were
to sink another backbox beside the socket for the FCU. Or you could
remove the existing socket box and widen the recess, then use a twin
single backbox (electrial wholesaler), that will take both the socket
and your FCU.



Aren't you supposed to label the light outside saying that its fed from
a ring main?..

And good idea perhaps to have a local switched fused spur outlet so as
you can flick it on and off as some of these lights can be switched to
come on continuously that way....
--
Tony Sayer

In article ,
Andrew Gabriel wrote:
There's a single 13A socket in a convenient location with an
apparently secure steel backbox., but I'm concerned that if I try to
drill a big hole in the back of the backbox, it may become loose,
generating more work, and I'd lose a socket anyway.

The boxes are normally pre-punched with 20mm holes. There's usually
a few mm of the circumference which isn't punched. Drill that out
with a something like a 4mm metal drill, push a screwdriver through
the small hole (or use the rear of the drill bit) and bend it over
to ping out the centre.

Or drill a hole close to one edge of the cutout and screw in a self
tapper, then pull that with pliers.

--
*Sherlock Holmes never said "Elementary, my dear Watson" *

Dave Plowman London SW
To e-mail, change noise into sound.