Lighting to a shed

[F]

Management is asking for a light on the garden shed. It's around 5 metres from the house with a paving slab patio between the two. There is a possible route round the edge under some block paving and then under a gravel run.

Could the supply be taken from, say, a fused spur fed from the nearest internal 13 amp socket (the utility room)? If so, what cabling and protection would be required between the two?

This is not necessarily DIY but I would like an idea on what to expect if we go ahead and put it out to a professional.

[Fredxx]

If going the professional route it might be cost effective to consider a solar panel LED light solution?

[Dave Liquorice]

For what purpose? ("to see by" is not a useful answer...). How often and for how long each time?

[F]

To see by... up to 4 or 5 hours at a time, up to 4 or 5 days a week.

It's Management so she reserves the right to change her mind.

[F]

I should have said: she's looking for a 30W LED floodlight. Does that help?

[John Rumm]

Yup.

Inside, ordinary T&E, then probably Steel Wire Armoured outside.

I would probably go with a weatherproof junction box or external socket on the outside wall of the utility - with the feed going straight through the wall into the back of it. Then connecting SWA down from there to the shed - you can bury it directly if required, or clip it to a suitable surface. Then the same trick again on the shed end with a junction box or socket to transition from the SWA back to T&E. I would go into the shed, stick a socket in there if it would be handy, then a FCU with 3A or 5A fuse to feed lights. Again could have an internal one in the shed if you want.

Electrically its not difficult, most of the work is routing the cables. So if you can DIY it would be significantly cheaper.

Probably way more detail that you need:

[williamwright]

That's very bright.

Bill

[polygonum_on_google]

Have you considered using a 12V LED light?

Then you wouldn't have the problem of mains cable (other than to the mains-to-12V "transformer").

Is 30W really needed? Our external lighting is around to 3 watts - four units round the building. Perfectly adequate for our needs (but possibly not yours). And they only come on for a couple of minutes. Excess light seems to be widespread. Nearest streetlamp has been out for months. Sadly they have just replaced it. Far nicer when it was dark (there is another one down the street so not exactly without light).

[polygonum_on_google]

Should say "2 to 3 watts".

[Jeff Layman]

For an LED, yes, but about the same as an old R7 120W halogen (and at least you can change those when they fail).

[Brian Gaff (Sofa]

Note, not talking about legality here, but for many years my old sheds supply consisted of a catenaries wire tight between house and shed, starting high on the house end, and strung under it some normal pvc covered three core cable. As you say all wired into a spur in the kitchen and the other end fed into the shed with 1 light and a socket for lawn mower etc. Not much good for a 3kw heater or anything but enough to get the job done and out of harms way. Hint, do note site a barbeque under the wire. grin. Brian

[Dave Liquorice]

Aye, VERY bright for inside of a shed. Define shed though our neighbours "shed" is about 15 x 10 metres. Our "shed" is 8 x 6 feet...

It would also rule out solar power for the evisaged 4 to 5 hours per day for 4 to 5 times a week. Unless you want to spend three figure sums on the system.

Battery, maybe, a 17 AHr sealed lead acid 12 V battery taken back to the house and charged after every session would work with a 30 W LED even with the losses of an invertor to take the 12 V up to mains for the light to bring it back down again. Assuming the amount of light required really is that that a mains 30 W LED will produce. That battery will weigh about 6 kg.

[polygonum_on_google]

There are many places where 30W LED is held to be more or less equivalent to 300W halogen.

Plus, typically, LEDs have at least a slightly higher colour temperature which changes effective vision significantly.

[Dave Liquorice]

No RCD? We don't know if the ring from which the spur is taken has an RCD or not. Even if it does, you don't really want a fault in the shed switching off part of the house. Putting an RCD in the shed doesn't mean that that one will trip first, the chances are it won't as the upstream one is likely to have other leakage earth currents flowing making it a little more sensitive.

[Chris Green]

As it's "on" the garden shed I guess it may be to light the way there rather than to provide light inside the shed. We have been considering a similar problem in our garden, needing a way to light the way across the lawn (which has some obstructions) to a cabin about

20 metres away.

[Chris Green]

The only way round the discrimination issue really is to have a separate circuit on the CU. The ring circuit in the house will have (if it is RCD protected) a 30mA non-time-delayed RCD, anything downstream will almost inevitably be the same - no discrimination.

I have my 'outdoors' wiring (lights, some sockets in a tack room, etc.) on a separate RCD in the CU for this very reason. Things outdoors do get water in them and you don't want the whole world to go off when they do.

(The main house CU is now all individual RCBOs but that came later)

[Chris Green]

Catenary supported mains cable is OK regulations-wise as long as it's done properly.

[ss]

Thats what I have done, its around 12 feet & about 8 feet above ground level, it is connected indoors to a plug socket and I just switch it on when required. Its not high load, garden trimmer or once in a while light for shed at night.

[spuorgelgoog]

Agreed, or even 24 volt. Interior and work lights for 24 volt are available from truck electric suppliers (and many are dual-voltage for cars and trucks).

Higher voltage would reduce volt drop.

2 amp at 24 volt = 48 watts of LED, which should be ample for even quite a large shed!

Owain

[wasbit]

If it's just for use as an outside light to show you the path, look at a battery powered LED security light. As it's LEDs & only on for minutes at a time the batteries last ages.