Max length of T&E hanging unsupported

[Me!]

I'm continuing to try and tidy up some old wiring, and I have one place where various cables, mainly T&E, hang vertically and unsupported for about 2.5 metres in a void. Is that OK, or do they need to be clipped or tied somehow over that length? I can't see any regulations about it but surely there must be a maximum allowable length.
This is existing cable, but all is pvc coated and single cored T&E so not too old and has presumably been hanging like this since the 1970's without any obvious problems yet. I just don't want to decorate this room and then later find out that I will somehow have to knock holes into this void space to clip the cables.

To clip the cables properly would probably require knocking holes through old wattle and daub, so I'd really rather not do it.

Many thanks.

 

[fernicarry]

Appendix D of the OSG (On Site Guide) suggests a 5m drop without additional support provided correctly supported at the top. Where that means clipped and a 'rounded support' to ensure minimum bend radius. There is a table to calculate the radius, looks like roughly 3 or 4 times the width of your T&E. Never seen anything that could be used as a rounded support available off the shelf. If I had to I'd probably put a clip either side of the bend to keep the cable a bit slack.

Personally I have a bit of an aversion to clipping inaccessible cables because it precludes using the old cable to pull in new ones at a later date. I've gone a little over the 5m for some cables but those will have two 45' bends around the sloping part of the ceiling before dropping rather than one 90' bend.

There's a proper sparkie on here who might shed a bit more light.

 

[Zebra]

Don't have Regs on me but wouldn't worry about that at all as long as it's hanging off something that won't hurt it, and it's not hanging off terminations.
Not sure I'd define 1970s wiring as "not too old" though, even though I'm sure there are folks on here with older!

 

[Me!]

Many thanks to you both.
The cables are well supported at the top over a gentle radius, so I shall be happy to leave them that way.

I'm only guessing at 1970's for the cable, but it is single cored copper in PVC insulation so hopefully it will last a while longer yet. Does PVC cable have a defined lifespan?
When we bought this house, there were many runs of single black rubber coated wires still in the loft. Or at least they were once rubber coated. By the time we found them, many yards of exposed live conductors had absolutely no rubber left on them at all!

 

[88v8]

Disclaimer... I am not a sparky...

So long as it's not overheated or exposed to uv, I believe PVC has an indefinite life.

High-load cable that cannot shed its heat - storage heater wiring plastered into the wall would be an example - will degrade faster, but our storage circuit from the 70s or earlier is OK insofar as I've unearthed* it. The cable was definitely less flexible, but no cracking when I bent it.

Even when degraded, like your olde rubber wiring, the brittle casing will be OK unless disturbed. I would expect single core PVC to outlast all of us.

If the house is damp the terminations may become corroded, but that's a very long term issue. Even on a car, 50 yo copper wiring can be perfectly good, as attested to by my own vehicle.

Ivor

* I didn't mean that........

 

[Zebra]

While I don't disagree with Ivor at all - many things are perfectly fine that the professionals would have you believe had reached the end of their useful life - the rule of thumb amongst sparkies when I was one (although I can't think where this actually came from) was that a house will need rewiring every 30 years or so. Having said that, that doesn't mean it would fail an inspection just because it was old, as long as everything is working correctly.

 

[Flyfisher]

On the one hand we have persistent plastics clogging up our rivers, oceans and landfill for thousands of years and generally causing ecological chaos, and on the other we have plastic wiring that only lasts 30 years before it needs to be replaced . . . increasing the chaos of the previous hand. The vicious circle of our throwaway society with its built-in obsolesence.

Yesterday I heard that GKN was in the news and apart from the takeover story, the thing that really struck me was that this engineering company is 260 years old. That's pretty much right at the start of the industrial revolution that has created the world we live in today. 260 years! An almost unmeasurably miniscule period of time in geological terms, yet also an almost immeasurably enormous impact in environmental terms. Oh dear, I'm in one of those moods today


Anyway, some interesting discussion about PVC wiring lifetime here: https://www.theiet.org/forums/forum/messageview.cfm?catid=205&threadid=5855

 

[Owain]

I'm only guessing at 1970's for the cable, but it is single cored copper in PVC insulation so hopefully it will last a while longer yet. Does PVC cable have a defined lifespan?

Indefinate unless it is affected by the dreaded Green Goo (degraded di-isoctyl phthalate) which occurs in some cables installed 1965 - 1971.