How best to wire garden lights

22 Jan 2007
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United Kingdom
Hey all.

Doing a little work in garden while the weathers good and while renovating house I was considering fitting some garden lights.

I'd like 3 or 4 short bollard lights running up one side of the garden. Contolled from a switch inside the house.

Now I know if running cable outside under ground Ideally I should be using SWA. But any bollards I see dont have a facility for terminating swa and then running 2nd swa length to next light.

so what would you do in this situation. would it be swa to water proof under ground junction boxes fitted under the bollards with standard cable from bollard to box?
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Alternitevly if I had transformer in house and were to run ELV bollards, would standard twin and earth be allowed to be buryed? Thinking in plastic conduit for mech protection and no need for earthed conduit if extra low voltage? or am I way off?
522.8.10 Except where installed in a conduit or duct which provides equivalent protection against mechanical damage, a cable buried in the ground shall incorporate an earthed armour or metal sheath or both, suitable for use as a protective conductor. The location of buried cables shall be marked by cable covers or a suitable marking tape. Buried conduits and ducts shall be suitably identified. Buried cables, conduits and ducts shall be at a sufficient depth to avoid being damaged by any reasonably foreseeable disturbance of the ground.

Potted junction boxes under ground work OK but where there is air inside the box this often ends up being replaced with water and they fail. So even if it says IP68 I would steer clear of any air filled boxes underground.

Twin and earth is for indoor use only.

Many bollards are designed to use concentric cable but this cable is not normally used by other than the DNO and one often has to do some adapting.

Extra low voltage uses higher amps and so really only suitable with very low power with the likes of LED lights.

But you can't really get a one design fits all and you have to way up your garden not a general garden taking into account things like local flooding.
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The trouser box with Re-enterable potting compound
would seem good option. Even simple Vaseline
will tend to stop water being drawn in. Filling the box with something other than air stops in the main water being drawn in. But of course non conducting some grease will conduct so I would not recommend grease.

You will also need a Black neoprene solid gasket and Galv pressed steel circular box lid plus double quantity of screw M4x12mm for each box.
BAS - I actually found an old post of yours this morning describing the trouser box, and its exactly what I need.

Do you know how wide the box is? think the bollards I was looking at were 75mm wide.(outer diameter)

Can get cable through wall in house to exterior junction box, run 1.5mm SWA down wall and along use the trouser box, its only 4 lights at 15w max bulbs each anyway.
Do you know how wide the box is? think the bollards I was looking at were 75mm wide.(outer diameter).
They're usually (perhaps always) just over 60mm in diameter - so there's a good chance that you'd be able to get them in - at least, in terms of size (could be a bit of a fiddle!).

Kind Regards, John
Right, thanks again guys, got a new problem. (no wonder most electritians I speak to hate outside lights lol)

Bought the cable/trouser boxes etc, bought the lights, but the opening underneath the lights is literaly one inch by one inch, and cant be unscrewed or better access made. It has a small water proof junction box in side that can pull down with a little sleeve for a normal bit of flex to enter. (doesnt seem like they thought of wiring regs when making them)

Now being the light pillars are quite short (about a foot) Would it be above board to:

Build a small box (wooden/decking material about one foot all ways) with a slab on top with light post mounded on it, then have with wiring in trouser box contained inside this with water proof cable gland and flex on output of trouser box straight up under light?

or would I need to use weather proof junction boxes inside (being that the ones I build would not technically likley to be totaly weather proof)

Couldnt find anything about the IP rating of the trouser box with the rubber gasket.
doesnt seem like they thought of wiring regs when making them
They aren't alone there. Makes me laugh when they say things like "must be installed in accordance with BS 7671", or "if in doubt consult a qualified electrician", when they can't be, and if you do he'll say the same thing.

Your plinth sounds fine - ditch the conduit boxes and use these:


They do an accessory for the SWA glands:


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