1.5mm cable for garden power?

^woody^ · 5 Jun 2009

I need to install some cable for garden power - a pond pump, and 4 sets of 3 12v lamps. There will also be 3 double sockets, but these are very unlikely to be used a the same time - most likely just a lawn mower in one socket at one time. Max run of cable is 12 to 15m to a point in the outbuilding, then there will be one or two 5m runs to sockets

Everything else is being taken care of - Part P, individual connection the the CU etc etc, so no comments there please

Anyway I need to get the cable in the ground before doing other work, and the actual connection of all this wont be done for a while afterwards.

Now, I already have some 1.5mm SWA, so would this be suitable?

I've asked a couple of our usual sparks, one said yes, one said no, another said maybe!

ColJack · 5 Jun 2009

yes if you use a 16A breaker...

conny · 5 Jun 2009

3 Doubles on a radial or ring?
Regardless that YOU may not use them all at the same time someone else might in your abscence, (builders come in to do a job use 1 for mixer, 1 for stone cutter 1 for radio, 1 for kettle etc, etc), or if you sell up.
Think it should be a minimum of 2.5 preferably 4mm to be safe.

PS I am not qualified spark but elec fitter so I may be wrong.

RF Lighting · 5 Jun 2009

1.5mm is woefully undersized.

4.0mm is what you need.

What exactly do you mean by "Part P, individual connection the the CU etc etc" is being taken care of?

Do you know all the regulations that govern this work, such as the depth at which the cable must be buried?

ColJack · 5 Jun 2009

according to the VD calculator, 1.5 PVC SWA is fine for 3KW at 20m..
just need to put it on a 16A MCB to protect it..

JohnD · 5 Jun 2009

^woody^ said:
Everything else is being taken care of - Part P, individual connection the the CU etc etc, so no comments there please

how is it being taken care of, and by whom?

There is a lot to be said for trenching in plastic waste pipe to draw your cable through. If you just bury it, how can inspection and test verify that you did not nick it with a spade, or joint it in the middle and wrap in sellotape?

ban-all-sheds · 6 Jun 2009

^woody^ said:
Everything else is being taken care of - Part P, individual connection the the CU etc etc, so no comments there please

So why on earth aren't you asking the person who is "taking care" of those things?

What's going to happen if she doesn't agree with the advice you pick, and won't any longer "take care" of them?

Oh.. wait... I get it.

denso13 · 6 Jun 2009

JohnD said:
There is a lot to be said for trenching in plastic waste pipe to draw your cable through

Or better still, proper cable ducting. Could be a nasty surprise for someone finding a handy waste pipe to connect to and putting a saw straight through it

^woody^ · 6 Jun 2009

A sparks is taking care of everything else, that's why I did not need comment on it. I don't know which one it will be yet, and if need be, he can check the cable install before its buried. The real issue is that the cable needs to go in soon before other work is done

As I already had three contrasting opinions, I thought I'd ask here to get a consensus

electronicsuk · 6 Jun 2009

^woody^ said:
A sparks is taking care of everything else, that's why I did not need comment on it. I don't know which one it will be yet, and if need be, he can check the cable install before its buried. The real issue is that the cable needs to go in soon before other work is done

As I already had three contrasting opinions, I thought I'd ask here to get a consensus

I think your idea of how part P compliance is achieved is a little skewed. However, as you don't want to hear about that, I would also suggest 2.5mm as a bare minimum, with 4mm being preferable.

Also, how do you plan on controlling the lights? If you only have one supply fused at, say, 20A back at the CU, you'll be needing weatherproof FCUs and switches for the lights. This would likely work out more expensive than another run of SWA for a dedicated lighting feed to be switched from indoors.

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1.5mm cable for garden power?

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