Twin and Earth used outside

[New Venture!]

Just had a (good natured!) ribbing from a fellow electrician about twin and earth being run on an outside wall. House we are working on has the feed to the upstairs shower running externally in white T&E clipped direct with no protection. This is something I usually avoid, and suggested I'd prefer it changed to NYY-J. "Typical usually works industrial, wants everything to withstand being hit by a JCB bucket" was one reply! He then showed me p 128 of the OSG re flat thermoplastic use. We've compromised on some trunking to protect. 

Am I as he said, being "typically industrial"? The guide does suggest so........

 

[Essex1]

Twin & Earth outside is something I Would not like to see. No way. 

 

[SLIPSHOD & SLAPDASH]

I have seen white pvc twin & earth clipped on a south facing wall, well i think it was white pvc as not much was left apart from the green copper cables. The light still worked though.

 

[Evans Electric]

Very little white T/E is used up here in the far north , its always grey , but both are affected by sunlight .   Don't know what it says in the OSG TBH  but clipped out of direct sunlight  doesn't seem to have much affect on the plastic TBH .  

Why black T/E isn't readily available I don't know.      I've done shower supplies up the outside many times but using black PVC conduit .  

 

[New Venture!]

It's a north facing wall. Neither of us installed it, the electrican I'm giving a helping hand to is fixing several C2 issues. I spotted the T&E and raised the issue. Still might gently suggest as we are already there and it's a fairly simple job why don't I just change it. 

 

[Murdoch]

It's a north facing wall. Neither of us installed it, the electrican I'm giving a helping hand to is fixing several C2 issues. I spotted the T&E and raised the issue. Still might gently suggest as we are already there and it's a fairly simple job why don't I just change it. 

Not sure I would give T&E used outside a C2 unless there are obvious signs of degradation ........

 

[New Venture!]

He hadn't given the T&E a C2, its other areas flagged as C2 we're fixing. It's me who's not too happy with this method of feeding a shower, but it's true I've spent most of my time in industry. 

I'll just change it, won't take long and I've got a bit of NYY-J left over from an install that will do the job. 

 

[Doc Hudson]

He then showed me p 128 of the OSG re flat thermoplastic use. We've compromised on some trunking to protect. 

Am I as he said, being "typically industrial"? The guide does suggest so........

That table, (C1 on page 128), or a variation of it has been in the OSG for quite a time now, in previous incarnations it was called appendix 3, (not appendix C), but as far as I know it is derived from information in Guidance note 1, where the equivalent table includes a few more cable types. (and the appendix designations are different again, e.g. Appendix F).  However what I find interesting is the general perception that flat T&E is a cable only intended for internal use and should not be used on any external walls. Is there any opposing BS7671 guidance suggesting that OSG and Guidance note 1 are poor workmanship, or is this just gut instinct or traditions passed down from word of mouth? 

Doc H.  

 

[Evans Electric]

That table, (C1 on page 128), or a variation of it has been in the OSG for quite a time now, in previous incarnations it was called appendix 3, (not appendix C), but as far as I know it is derived from information in Guidance note 1, where the equivalent table includes a few more cable types. (and the appendix designations are different again, e.g. Appendix F).  However what I find interesting is the general perception that flat T&E is a cable only intended for internal use and should not be used on any external walls. Is there any opposing BS7671 guidance suggesting that OSG and Guidance note 1 are poor workmanship, or is this just gut instinct or traditions passed down from word of mouth? 

Doc H.  

As I've said before Doc, theres a lot of things in our trade that are assumptions based on hereasay, but I'm  sure I've read this up over the years , that is , flat  T/E is subject to the affects of UV radiation .  First read in the ASEE Guide to the 15th  edition  I'd imagine , where black PVC is said to resist the affects of sulight .  

 

[steptoe]

I've been to jobs where flat T&E clipped across the top if a cupboard has been coded C2 and stated it must be enclosed in trunking, :shakehead

Waaaaaaay too much hearsay imho

 

[binky]

it's not about the cable as such, it's about suitability for the environement it is installed in. FTE is not UV stable and therefore is not suitable to be installed were exposed to UV, which translates as not outdoors.

 

[professional]

Where DO people get all of this vacuus s**t from?

BS7671 does not state that PVC t&e cannot be used outside - it merely suggests that materials and methods of construction/installation should be suitable for both the anticipated use and environmental conditions.

Since BS7671 is non-statutory and merely guidance, it is down to the designer to use their knowledge and experience to decide on what constitutes compliance with both the Building Regulations and the EAWR. 

Unfortunately, the lack of said attributes amongst many "competent" installers ( thank you scam providers ) coupled with the lack of any requirement to INSPECT & TEST an installation ( thank you DCLG ) leads one to wonder what the inception of the scams has actually acheived?

If the ( in excess of ) £200 million spent on scam membership had been spent on real training and qualifications, I wonder what COULD  actually have been acheived over the last ten years?

 

[Sharpend]

And j thought you'd turned a corner and was befriending the scans and dclg there for a moment!  :innocent  

how are you these days? 

 

[Murdoch]

Where DO people get all of this vacuus s**t from?

BS7671 does not state that PVC t&e cannot be used outside - it merely suggests that materials and methods of construction/installation should be suitable for both the anticipated use and environmental conditions.

So you would install T&E outside then?

I see you have got round the swear filter - you bad person!

 

[binky]

BS7671 does sate that materials need to be suitable for the environment in which they are installed.

 

[steptoe]

I think the biggest problem is the people designing the installations need to be suitable for the job they are in,,,,, 

 

[phil d]

Some very interesting comments here,one member mentions that it does not state anywhere in BS7671 that T&E cannot be used outside and he is quite correct.Another member states that BS7671 says materials must be suitable for the environment in which they are installed,he is also quite correct. My pet hate is when people state that because something doesn't comply with BS7671 then it is illegal,it is not!BS7671 is a guide and not statute,and therefore not enforcable by law.Ok now depart from those regs and,if anything goes wrong then it is up to you potentially to justify why you did what you did in a court of law,that however is a different matter.I think the one thing we ALL agree on is the need for better education,and I think this needs to start at the top,a classic being AMDT3 non combustible CU's,ninety percent of the time it's not the fault of the CU,but the fault of the installer who doesn't tighten up the connections properly,education again?

A cracking post with interesting comments from all involved.

 

[New Venture!]

Can I echo Phil D and say thanks to all for this very interesting debate. Steptoe, you made me think re suitability for the job you're doing. Voltage drop, current handling etc. I'm very happy with, but admit my tendency is to design for eventualities that are very unlikely to exist in a domestic environment. This could lead to a higher than necessary cost to my customer. 

Would I use T&E outside? Probably not, I like NYY-J, it's easy to gland and offers (in my opinion) superior UV and mechanical damage protection. Also for fairly short runs (<10 metres) the cost isn't too much higher.

This is why this forum is good. I'll keep posting and hopefully we can continue debating.

Cheers,

JB. 

 

[binky]

the other issue with any outdoor cabling is vermin and cats (both being vermin according to Steps :^O ). Half way up a wall is not likely to suffer anything, along the top of a wall or fence is very likely to get damaged. FTE also isn't designed to flex, I had a case where a DIYer had run cable in hose-pipe on a catenary wire to his garage about 20m away, which had bcome loose over time. The cable had dead shorted at a stress point close to the house.