External lighting cable query and general query.

DrEvil · 18 Oct 2009

Hi there, I want to add two security lights round the back of my house.

I had an electrician over (used this guy on previous job) but he's not free for a bit and not that willing to come over to do this small job, so thought I may do it myself. I initially went to an electrician because I wasn't sure if it was Part P and erred on the side of caution (now realised it doesn't require any Part P certification as can be run off existing circuit).

Anyhow, he decided due to the circuit configs in the house, that the best thing to do is the run of a spur from a socket in the rear dining room. Then to a new single box which has a fuse switch (5A). From the back of this I can run a cable directly through the wall to the outside and then take the cable and connect them.

So first question as I'm here - does that all sound sensible?

Second and main question - is he talked about either using conduit or some pirelli/firetrap wire for the outside and tack that to the walls direct. I'm not sure exactly what this is and can't seem to find it on screwfix etc - can someone direct me to the right stuff to use?

Thanks

PrenticeBoyofDerry · 18 Oct 2009

The circuit or at least the addition to the circuit must have RCD protection. This should be at your Consumer unit or Via the fused connection unit that you are installing, your cable sounds like it is coming through the wall at a lower level, so needs mechancical protection, so steel conduit or cable worth considering is SWA or SY
http://www.tlc-direct.co.uk/Products/SW1dot5slash3.html
http://www.tlc-direct.co.uk/Products/MF1dot5slash3.html

Taylortwocities · 18 Oct 2009

Or 1.5mm² Hi-Tuf.
Doesn't need special glands like SWA, you can just use stuffing glands. http://www.tlc-direct.co.uk/Products/HT1dot5slash3.html

DrEvil · 19 Oct 2009

Hi and thanks for the replies.

In terms of the wire, i think hi-tuf was the stuff the electrician was talking about as he said it didn't need the armoured stuff, although looking at those prices, the armoured stuff is cheaper! Is http://www.screwfix.com/prods/53747...LV-Armoured-3-Core-Black-1-5mm-25m-Cable-Reel ok as screwfix is easy for me to get to?

Any particular RCD I should use (Screwfix have several volex ones).

Cheers!

Taylortwocities · 19 Oct 2009

SWA itself may appear cheaper but then you are going to have to add the special SWA glands (a pair for each length of SWA so that is two pairs) then you'll have to work out how to keep the earth of the armour continuous.
That will probably mean weatherproof termination boxes next to each light just to terminate the SWA.

Hi-Tuf is sooooooooooooo much easier...

Steve · 19 Oct 2009

Why IS Hituff so expensive?

ccrowe · 19 Oct 2009

Steve said:
Why IS Hituff so expensive?

I suspect it's because not enough people use it. Shame, as it's the mutts nuts.

DrEvil · 21 Oct 2009

Ok, now I've rexamined the circuit I've got a few more questions.

I have a socket in my breakfast room. It is not in a circuit at all and just connects to the fuse board direct with through a single cable.

Can I spur a RCD off this as it is in a much more sensible location for a switch and would have the benefit of using less wire.

Also will this RCD do http://www.screwfix.com/prods/83049/Electrical-Supplies/RCDs/Volex-13A-RCD-FCU. I'd swap the fuse for a 5A one. Alternatively is there one with an on/off switch?

Taylortwocities · 21 Oct 2009

That single cable from the socket that goes to the consumer unit.

Does it go to its own contact breaker in the fuseboard?
What is the rating of the breaker.>

If it is on its own breaker then you MIGHT be able to use it.
If it shares a breaker with other wires then probably not.

Re the RCD. Those green & blue buttons will provide an on/off function.

DrEvil · 21 Oct 2009

Single cable to its own contact breaker which is a wylex nsb32 240V.

Aragorn84 · 21 Oct 2009

a 32a MCB covering a radial with one socket on the end sounds a bit excessive....

Is the cabling actually capable of carrying 32A?

Taylortwocities · 21 Oct 2009

If the cable is 2.5mm² then the cb should be 20amp absolutley maximum.

DrEvil · 21 Oct 2009

Well my kitchen used to be wired up very strange - one side which included the wsahing machine was wired via this socket from the breakfast room (which was on one circuit loop) and another side took power from the rear reception room (which is on its standard downstairs plug sockets circuit loop).

The electrician had a fit when he saw it and put the whole kitchen an individual circuit on a new mini wylex board which has a RCD.

That left this single socket connected directly to the fuse board (which is wylex new style but no RCD).

I'll check on the wire tomorrow but its the same cable that's used in all my wiring around the house. Is there a minimum mm it should be.

Aragorn84 · 21 Oct 2009

As taylor says, if its "normal" 2.5mm cable then it should be on a 20A breaker.

Other than the incorrect breaker, your plan sounds alright to me.

ban-all-sheds · 22 Oct 2009

ccrowe said:
I suspect it's because not enough people use it. Shame, as it's the mutts nuts.

And about as pleasant to manipulate.....

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External lighting cable query and general query.

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