Outside fence lights

[MisterBoy]

I want to put some outside lighting along this fence in our little car park.
It's 11m long and I am thinking of some basic outdoor bulkhead lights, probably 3.
At the far end it joins an old wall and about 5m along that is an outdoor socket. My plan is to take a spur off that using an ip55 box then run standard lighting cable through 20mm plastic conduit among the back of the fence. Another small waterproof box each light, probably use those wago connectors.

I dabble in a bit of home wiring so for me it's not a tiny project, any advice or pitfalls to avoid?
I was wondering how to get the cable to the lights through the fence and keep it watertight.
Also getting the cable through a long conduit run, what's the easiest approach?
And, would you recommend a fused spur switch where I take it off the outside socket? That's on a dedicated circuit so I can turn it off without losing house sockets.

Thanks.

 

[Harry Bloomfield]

Using armoured cable is the more obvious solution rather than conduit. That will need armoured cable glands, at every cable end. Aim to only make holes in the boxes, in what will be the bottom of the boxes, so water runs out, but not in.

Best think now, about how you are going to switch them, rather than later. Do you intend only turning them on when needed, manually. Might automatic be better? Maybe a PIR to turn them on, or might you want them on dusk until 11pm or maybe on until dawn?

If you have good reliable broadband and wifi, a Smart Switch would do the latter options at minimal cost.

 

[MisterBoy]

I was wondering about SWA but I've not worked with it before... And I have the stuff lying around otherwise. Assume that's more a matter of preference/style either is acceptable?

Good catch on switching. I actually am planning on a 'smart switch', found some which can fit in the boxes. I would prefer a physical backup though as it's bloody stupid if you can't turn your lights on/off due to internet issues when you're standing next to them The unit I found allows you to wire in a switch to toggle the state so you can use both methods. Prior to finding that, I'd considered wiring a waterproof switch in parallel with the smart switch

 

[oldbutnotdead]

Is this a public area? If yes then step away, your potential liability if anything goes wrong is infinite.
Plastic conduit isn't ideal for a job like that, metal conduit or (as mentioned above) SWA will give a much more robust install.

 

[MisterBoy]

Looking at Screwfix, SWA isn't exactly pricy I guess 1.5mm is more than adequate for 3 or 4 led fittings? For the sake of a few quid alone I'd go that route but how is it to work with, fitting glands and so on - do I need special tools?
Obviously less flexible but no need to be fiddling with conduits. At this size cable, can I bend it reasonably?

 

[oldbutnotdead]

If you're terminating into adaptable boxes with plenty of space it isn't difficult stuff to work with. Check volt drop for cable sizing (useful calculators on tlcdirect), best to use 3 core rather than relying on the armour as cpc. Hacksaw, good cutters, pliers, spanners will do

 

[Harry Bloomfield]

Looking at Screwfix, SWA isn't exactly pricy I guess 1.5mm is more than adequate for 3 or 4 led fittings? For the sake of a few quid alone I'd go that route but how is it to work with, fitting glands and so on - do I need special tools?
Obviously less flexible but no need to be fiddling with conduits. At this size cable, can I bend it reasonably?

1.5mm is more than adequate for a few LED light fittings, you would be better with 3 core, then use one core as a separate earth, but the steel wire also needs to be earthed, so you need banjos to do that, one per gland.

For each termination you will need 1x 20mm S gland, 1x 20mm locknut, 1x 20mm banjo, 1x gland shroud.

Tools - 20mm hole saw; junior hacksaw; spanners to fit the glands and locknut, Stanley knife.

You simply nick the armouring all the way round (carefully), by sawing through the black PCV, take off the black PVC, then waggle the armouring about to get it to snap where nicked. Fit the shroud, the outer nut of the gland, then trim the outer black back an inch or so. Twirl the inner core round, to fan the armour out, then fit the main part of the gland, screw together tightly trapping the armour - make sure all the wire goes fully in.

The inner black PVC then needs trimming back even more carefully, just score it, rather than cutting all the way through and risking damaging the cores.

Bending such small sizes is quite easy, no more difficult than a hose pipe - I have dealt with 4" diameter armoured cables, lots of them.

You will need the correct size of cable clips, they do a single screw plastic saddle.

 

[MisterBoy]

So would this be the right size, don't understand 20, 20s etc?
https://www.screwfix.com/p/tower-rubber-exterior-gland-kit-20s-2-pack/25996
Are banjos those things that look a bit like ring pulls?

So if I'm running 3 bulkhead lights among the fence I ideally want a weatherproof box directly behind each one, and the SWA passes through each box using a pair of glands one on each side until the last box which just has one?

Out of interest why does SWA need such chunky fixings, rather than the cheap plastic ones you can use for regular cable? Is it a structural thing?

 

[JohnW2]

Check volt drop for cable sizing (useful calculators on tlcdirect), best to use 3 core rather than relying on the armour as cpc.

There's surely no way that VD is going to be an issue for a few LED lights, for any credible size of cable, is there?

Kind Regards, John

 

[JohnW2]

Out of interest why does SWA need such chunky fixings, rather than the cheap plastic ones you can use for regular cable? Is it a structural thing?

Primarily so that there can be a satisfactory electrical connection to the armour of the cable - although I suspect that 'less chunky' ones could be produced if they so wished (they seemed to have been designed by those more used to plumbing fittings!)

Kind Regards, John

 

[MisterBoy]

I've seen the debate about whether to use the sheath or a dedicated earth wire before, but I didn't realise you had to earth the outer sheath regardless. Is that so if someone chops through it, they hit earth first?

 

[Harry Bloomfield]

So would this be the right size, don't understand 20, 20s etc?
https://www.screwfix.com/p/tower-rubber-exterior-gland-kit-20s-2-pack/25996
Are banjos those things that look a bit like ring pulls?

Yes, like a ring pull. It's the 20s size you will need. Don't worry about about volts drop.

 

[JohnW2]

I've seen the debate about whether to use the sheath or a dedicated earth wire before, but I didn't realise you had to earth the outer sheath regardless. Is that so if someone chops through it, they hit earth first?

Exactly. The armour must be earthed, for essentially that reason, even if one of the cores within the cable is also being used as the 'earth'.

It's not so much so that one has to 'chop through the armour first' but, rather, so that if one does chop through the whole cable with a metal tool, one is likely to bring live conductors and that (earthed) armour into contact, thereby blowing a fuse or tripping a breaker.

Kind Regards, John

 

[seasickstevie]

For that job with such minimal load, and considering a thinner cable might look less conspicuous, I'd go for two-core and use the armour for the cpc/earth. It's perfectly adequate, so long as good solid connections are made with the brass glands, and obviously the banjos are earthed correctly using brass nuts and bolts connecting an earth wire to the supply.

A slightly thinner cable would make for neater bends.

Alternatively, if you did use three-core, you could do what I've done on a similar job recently. Use the third core for a permanent live, and put a PIR at each end of the run (or a manual one-way switch if that's a consideration).

If the fittings are suitable, you could bring the glands into each side, rather than a separate adaptable box. It is always a nice idea to aim for bottom entry, but with the shrouds, and some sealant over the meeting of the gland and fitting, it should be okay. I usually put a small drain hole in the bottom.

 

[markyd1]

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