best cable

[richard]

I want to run some cable along a wooden fence for three outside bulkhead lights. What is the best type to use?

[Ian Stirling]

Armoured cable, properly secured onto the fence.

[Christian McArdle]

SWA armoured. Although Hi-Tuf has the requisite UV protection for outdoor use, a fence location really needs something extra for mechanical protection, too. Besides, SWA is cheaper, especially for long runs when the required glands don't play a disproportionate role.

Christian.

[Dave Stanton]

Don't the regs have something to say about NOT running wiring along things like wooden fences because they are not permanent structures ?.

Dave

[Ian Stirling]

I believe they do. IMO, if they are bulkhead lights mounted to the fence, there isn't a more sensible place to put them.

[Stefek Zaba]

Kinda. The Regs themselves don't, I believe, go into this sort of detail: they have a more general requirement that cables used in an installation be adequately protected against foreseeable mechanical damage. It's the On-Site Guide which expands that, in a kinda-advisory way, into the suggestion that walls are a Permanent Support, but that fences aren't; in the same way that unprotected surface-run wiring is OK in a domestic setting (not pretty, of course, but unobjectionable for cellars, lofts, and similar low-traffic areas) but would be well out of place in a commercial workshop or warehouse.

Blanket rulings like "no cables attached to fences" bring out the curmudgeon in me: there are fences and fences in this world. A rickety affair of chestnut pailings and twisted galvanised wire would be inadequate (subject to too much flexing); a similar objection might, with less force, apply to an all-wood almost-secure post-n-panel garden fence; contrariwise, a garden fence with well-set concrete posts, particularly with well-fixed concrete bargeboards to which an armoured cable is secured (visible, so not likely to be hit by a spade), or a well-set post-n-rail setup, strikes me as no less permanent a structure than concrete garages or wooden sheds, to which such cable is regularly secured as it enters the outbuilding. "Common" sense applies, and is indeed what the Regs (as opposed to OSG or trade folklore) stipulates...

Stefek

[Dorothy Bradbury]

Instead of the best cable, why not the best lighting? o Fences can be blown down o Environment when a fence is blown down isn't great for fixing cabling

That is particularly so if the feed is shared by shed, greenhouse, other lights.

Frankly for a wooden fence... o SWA is ugly on a fence o So SWA to bulkhead lights fitted the fence posts o Since fence posts can rot/fall-down, perhaps the light on a post directly in front

Since outside lighting should really be low-energy... o You could use fluorescent (Black TLC Orbits look nice in 18W)

---- which will flicker on turnoff if used on their own with some PIRs on turn-off :-) o You could also use ELV - solving the problem

---- 12V spots, uplighters, ground-lighters, annoy-the-wildlife-lighters

---- proper IP rated units, with 20-50W bulbs/moth-incendaries available

If you need SWA (cable/glands/box, clips, screws, first-aid-kit) then cost-wise ELV might not be so different - and more aesthetic too.

Some people use festoon cable on fences for lighting, but it is only temporary. Most fencing is a temporary structure and does get blown-down if it presents a solid structure to the wind as opposed to one which allows air to partly go thro.

I would use ELV, no SWA trench, no fat SWA on a fence either.

Many bulkhead lights are poorly made re low IP rating, often failing when it is too cold/wet/windy to fix them - ELV units can be IP67 without costing $$$$. Archaeologists will call it the second dark age when they find solar lighting.

[Dave Stanton]

Thanks Stefek, best summing up I think.

Dave

[Pete C]

Hi,

If you just want some low level path illumination consider some white LED clusters run off low voltage AC.

Not too hard to DIY and would look _far_ better than bulkhead lights and mains cable (all IMHO).

cheers, Pete.

[Ian Stirling]

Cheap white LEDs often fall in output dramatically after 1000 hours, even without overdriving.

[Pete C]

Can you point to any references on the web?

The most sensible figure I've seen is a loss of 10% output every 1000 hrs at rated output, that would give 6-7000 hrs to half brightness. If run at reduced power they should last a lot longer as the percentage loss per 1000hrs will be lower.

cheers, Pete.

[Ian Stirling]

No .

It really, really depends on the maker. If it's a reputable maker, then things tend to be better, and they conform to the datasheet.

But LEDs are such that small levels of contaminents of unobvious sorts can gradually poison the phosphor, or make the case yellow.

If buying solely on price/LED, at a given initial brightness, there are some LEDs out there that will look good initially, and rapidly tail off. Some special purpose LEDs with odd colours (pink) can even die in hours.

may be enlightening.

[usenet]

Ah, thank you! I'm about to run an SWA cable along a short length of post and rail fence with my 'common sense' hat on.

Over the week-end I removed a redundant part of the fence and having seen how deep the posts are in the ground it most definitely is the next best thing tp 'permananent'. They are 7ft long posts with at least 3ft in the ground.