16mm T&E for external building

[ban-all-sheds]

apart from cost... t&e in conduit is half the price.

My apologies.

no GOOD reason not to use SWA.

 

[JohnW2]

You say that DNOs do not use 'special PVC', but is it not more UV resistant than standard white or grey sheathed T+E? 'Ordinary' PVC

Nope it is exactly the same with the same product code on the drums as standard "meter tail" PVC

Fair enough - but that's not what I asked. As you correctly quoted, I asked whether the UV resistance of what you use was greater than that of "standard white or grey sheathed T+E", not 'meter tails'.

Kind Regards, John

 

[westie101]

Apologies John
No not to my knowledge

 

[roasty]

16mm 2 core SWA is about £3.60 a metre, you aren't going to save much money messing around with T&e or tails in conduit, plastic pipe or clipped exposed.
Not my money, but if it were me, it'd be SWA all day long. Do it properly you won't regret it.

 

[bernardgreen]

I suggest that some of you go and look at DNO mural wiring that is clipped to properties all over the country.
In the main it is PVC/PVC 16mm or 25mm meter tails.

Westie is correct, I have seen some of the mural wiring. And it worries me. Like where the cables are run 6 inches below a thatched roof and supply three properties. These cables could be 40 years old.

I guess like old vulcanised rubber these cables are fine until disturbed. In about a years time they will have to be disturbed when the roof is re-thatched.

 

[JohnW2]

16mm 2 core SWA is about £3.60 a metre, you aren't going to save much money messing around with T&e or tails in conduit, plastic pipe or clipped exposed.

Indeed. Actually, per current TLC prices (excl VAT) 16mm² 2-core SWA is £4.15 per metres, as compared with £3.91 for 16mm² T&E - a difference of 24p (28.8p incl VAT) per metre. Hence, by the time one has bought conduit (or whatever), using T&E would almost certainly be more expensive. Admittedly, one would also have to buy glands for the SWA (a few pounds) - and some would favour 3-core SWA (£5.64/m excl VAT, £6.77 incl VAT).

Interestingly, if he used 10mm², at TLC prices T&E is much more expensive than 2-core SWA!

Whatever, I really do not see how the OP can perceive a significant enough cost difference to persuade him not to use SWA.

Kind Regards, John

 

[JohnW2]

Westie is correct, I have seen some of the mural wiring. And it worries me. Like where the cables are run 6 inches below a thatched roof and supply three properties. These cables could be 40 years old. ... I guess like old vulcanised rubber these cables are fine until disturbed. In about a years time they will have to be disturbed when the roof is re-thatched.

I suspect that, in contrast with VIR, UV-exposed PVC/PVC cables (with UV protectors) do not usually present an appreciable immediate risk, even when disturbed. Whist the sheath may become brittle, and hence crack when disturbed, I would doubt that UV would penetrate through the sheath to the insulation, which therefore ought to remain in good condition (and hence not crack).

Kind Regards, John

 

[JohnW2]

Apologies John ... No not to my knowledge

Fair enough. Probably for no good reason, I had always assumed that the black-sheathed (and maybe also brown-sheathed) cables had UV-protection, whereas grey/white-sheathed T+E didn't.

So, was I right to be a little concerned about this (albeit the neighbour's paint was probably affording some UV protection!):

Untitled

• JohnW2
• 6 Aug 2011
• 2

The nice WPD man who 'temporaily' re-clipped it (2 or 3 years ago!) didn't seem worried, since he didn't use any PPE ("I can't work with gloves on"!).

Kind Regards, John

 

[westie101]

In that case as long as it has been visually inspected and shown to be OK there is no need to wear gloves. They only need wearing if live conductors (i.e. the actual metal) are exposed.

Looking at the murals in the photo, at that distance it looks fine and is of no concern.

So I do wonder what the huge fear of PVC used outdoors is, I've seen little evidence it deteriorates as some stress

 

[ban-all-sheds]

Whatever, I really do not see how the OP can perceive a significant enough cost difference to persuade him not to use SWA.

Nor an installation difference - it will not be he making off the ends.

 

[ban-all-sheds]

So, was I right to be a little concerned about this

Possibly - it would depend why.

I would be concerned about the ghastly idea of cables clipped to the wall in the first place, irrespective of their type.

 

[JohnW2]

In that case as long as it has been visually inspected and shown to be OK there is no need to wear gloves. They only need wearing if live conductors (i.e. the actual metal) are exposed.

Is that wise? If the sheath and insulation had become brittle, they might not crack and expose live conductors until they were handled - which could be a bit late to decide to put the gloves on!

Looking at the murals in the photo, at that distance it looks fine and is of no concern.

As I described in the original thread, my main concern was that the clips were progressively breaking and hence the length of the sagging portion gradually increasing (to the left in photo), and there were also many clips broken in the vertical portion of the cables which are not visible in the photo. It would only have taken a small number of further clips to break for the entire weight of a large sagging portion of the cables to be hanging off the connections to the (I think 'ABC') cable to the pole.

So I do wonder what the huge fear of PVC used outdoors is, I've seen little evidence it deteriorates as some stress

I've certainly seen evidence that the PVC sheath of ordinary (grey/white) T&E can become brittle if continuously exposed to sunlight for 20 or 30 years, but even that is not really a problem so long as the cable remains disturbed. As I wrote to bernard, I would doubt that the inner insulation would get affected by UV.

Kind Regards, John

 

[JohnW2]

So, was I right to be a little concerned about this

Possibly - it would depend why.

See my recent response to westie.

I would be concerned about the ghastly idea of cables clipped to the wall in the first place, irrespective of their type.

I agree - but, as I've said before it's my neighbour's wall, so I don't really have any say about it. I presume that the situation arose for historical reasons. Until about 1950, that house was part of what is now mine. I imagine that the supply then entered 'the property as a whole' close to where it arrived from the pole, hence no mural wiring. However, when the properties were split, there was a need to provide a separate supply to 'my' bit, which is, I imagine, when those mural cables (probably predecessors of the current ones) first appeared. A direct overhead run from the pole to my property would have gone partially over the neighbour's roof, and maybe that would not have been allowed?

Kind Regards, John

 

[westie101]

Is that wise? If the sheath and insulation had become brittle, they might not crack and expose live conductors until they were handled - which could be a bit late to decide to put the gloves on!

As the guys are trained it is up to them to asses the risks on each work site. Certainly there is no history of incidents occurring to staff in the way you describe, so that does suggest that as an industry we have the right approach

 

[JohnW2]

Is that wise? If the sheath and insulation had become brittle, they might not crack and expose live conductors until they were handled - which could be a bit late to decide to put the gloves on!

As the guys are trained it is up to them to asses the risks on each work site. Certainly there is no history of incidents occurring to staff in the way you describe, so that does suggest that as an industry we have the right approach

Interesting. The absence of incidents certainly suggests that these cables are not really a problem (as I said, I would not expect the inner insulation to be affected by UV - unless, of course, the sheathing were visibly absent!). I still wonder whether the sheathing is not perhaps more UV-resistant than you seem to believe.

However, the chap who did the re-clipping certainly seemed to believe that he was "meant to" wear gloves to do it, but said that he would find such work very difficult with gloves on.

Kind Regards, John