magnethead

ICF's soaking up the plasticizer

Recommended Posts

Posted (edited)

Hi,

I read this article here about a little bunch of network cables , causing a standard 40mm PVC plumbing pipe to warp and leak,  by leaching their plasticizer into the pipe.

 

Network cable causing leaks in plumbing

 

so that got me wondering about what kinda risks are there really with ICF and electric cables, the manuals call out that electric cables should always be in conduit for that reason, so the insulation around the electric cable doesn't leach out all it's plasticizer and become brittle. Is this a real risk?

How far do the electric wires have to be kept from the surface of the ICF? 

 

Would you have any comments on my mates, breaker box install?

Thanks

 

 

IMAG1884_1.jpg

Edited by magnethead

Share this post


Link to post
Share on other sites

There is a long known about issue of PVC in contact with polystyrene, but that article seems to suggest some forms of PVC don't like being on contact with other forms of PVC. I have never come accross that.

 

I have seen cables passed through a wall with some form of polystyrene insulation for a long period and you can see physical "melting" or flowing of the PVC jacket, but I have never actually seen a cable that has failed because of this.

 

If your brand of ICF is one based on some form of polystyrene then it would be a pretty good idea to put something behind the cables so they are not touching the polystyrene.  PVC conduit does not "solve" the problem as that is still PVC but being thicker it would take longer for any effect to manifest itself.

 

For that matter I would be wanting PVC pipes to avoid touching the polystyrene. 

Share this post


Link to post
Share on other sites
Posted (edited)

I also believe there is a different spec of wiring --eg insulation is different material  for inserting directly into the foam ,but fitting in electrical conduit would also work 

how about this for ducting to distribution board

https://www.electricalworld.com/en/gb/Stadium-1M-4x2-White-Flat-Rectangular-Flat-Ducting/m-3526.aspx?PartnerID=1&utm_source=google&utm_medium=cpc&utm_campaign=UnitedKingdom&gclid=CjwKCAjwqLblBRBYEiwAV3pCJmmisvX-D83TcQelQ5wjEUPAkvRpImkJXXdDkQNa-d_oTb9bs-XMHxoC0pEQAvD_BwE

Edited by scottishjohn

Share this post


Link to post
Share on other sites
Posted (edited)
34 minutes ago, ProDave said:

There is a long known about issue of PVC in contact with polystyrene, but that article seems to suggest some forms of PVC don't like being on contact with other forms of PVC. I have never come accross that.

 

I have seen cables passed through a wall with some form of polystyrene insulation for a long period and you can see physical "melting" or flowing of the PVC jacket, but I have never actually seen a cable that has failed because of this.

 

If your brand of ICF is one based on some form of polystyrene then it would be a pretty good idea to put something behind the cables so they are not touching the polystyrene.  PVC conduit does not "solve" the problem as that is still PVC but being thicker it would take longer for any effect to manifest itself.

 

For that matter I would be wanting PVC pipes to avoid touching the polystyrene. 

from what my sparkie told me --real electrical conduit --not plumbing stuff  -is not pvc but some sort of modifed plastic 

it will shatter if you jump on it --so more like an abs blend --pvc usually just squishs when you stand on it .#

worth checking with an electrical parts supplier though .

my guess is the cheap brand is pvc --and more expensive is the right stuff

Edited by scottishjohn

Share this post


Link to post
Share on other sites

I always thought the LSZH cable was ok to run alongside EPS? 

Share this post


Link to post
Share on other sites
5 hours ago, ProDave said:

There is a long known about issue of PVC in contact with polystyrene,

 

Specifically, PVC with plasticizer in it. uPVC (u = un-plasticized) should be OK so rigid PVC pipe shouldn't have a problem with polystyrene. Interesting about rigid PVC being affected by plasticized PVC, though, which would presumably mean the rigid PVC would suck the plasticizer out of the cable insulation making it brittle.

Share this post


Link to post
Share on other sites

We have approx 1200m of LSZH twin and earth installed in our ICF build. Costs a chunk extra, to be sure - first, because its roughly 30% more expensive to buy 6242b cable than the same thickness of the usual grey 6242y cable; second because you're embedding the cable in insulation, you have to derate the cable. That means you end up running radials and rings in 4mm2 cable instead of 2.5mm2.

 

Here's an idea of the hell I am in with cabling... 

 

received_2302410503369217.thumb.jpeg.d0318a19bd4240cc20f9b55b3c715763.jpeg

 

That will one day be a home automation system, with DMX controlled lighting and power circuits, and either Loxone or Unipi managing it all. 

 

For now, it's just my nightmare that comes true every time I visit site. 😭

Share this post


Link to post
Share on other sites
Posted (edited)
9 hours ago, Nelliekins said:

We have approx 1200m of LSZH twin and earth installed in our ICF build. Costs a chunk extra, to be sure - first, because its roughly 30% more expensive to buy 6242b cable than the same thickness of the usual grey 6242y cable; second because you're embedding the cable in insulation, you have to derate the cable. That means you end up running radials and rings in 4mm2 cable instead of 2.5mm2.

@Nelliekins

maybe it would end being cheaper to run std cable in ducting ?

as well as making it easy to pull another cable  later you didn't think you would need?

that picture looks like a good reason to use ducting,at least part of the way  to make it neat and tidy 

Edited by scottishjohn

Share this post


Link to post
Share on other sites
On 10/04/2019 at 15:13, scottishjohn said:

from what my sparkie told me --real electrical conduit --not plumbing stuff  -is not pvc but some sort of modifed plastic 

it will shatter if you jump on it --so more like an abs blend --pvc usually just squishs when you stand on it .#

worth checking with an electrical parts supplier though .

my guess is the cheap brand is pvc --and more expensive is the right stuff

This stuff is polyethylene  and the datasheet recommends it for use embedded in concrete pours

https://www.tlc-direct.co.uk/Products/FXKVR63.html

 

(Interestingly it doesn't claim suitability for stud walls, ceilings or screed. I guess those are too vulnerable and ducting should provide more protection)

Share this post


Link to post
Share on other sites
29 minutes ago, joth said:

This stuff is polyethylene  and the datasheet recommends it for use embedded in concrete pours

https://www.tlc-direct.co.uk/Products/FXKVR63.html

 

(Interestingly it doesn't claim suitability for stud walls, ceilings or screed. I guess those are too vulnerable and ducting should provide more protection)

 

The flexible duct linked to is primarily for use underground and through slabs and walls, not internal or external use as conduit.  Polyethylene isn't very UV resistant, so whilst this duct is fine when buried, it may well degrade if used as conduit that's exposed to light.

 

Plastic electrical conduit (as distinct from duct) is usually made from uPVC or sometimes ABS, so that it can be solvent welded.

  • Thanks 1

Share this post


Link to post
Share on other sites
On 05/05/2019 at 09:09, scottishjohn said:

@Nelliekins

maybe it would end being cheaper to run std cable in ducting ?

as well as making it easy to pull another cable  later you didn't think you would need?

that picture looks like a good reason to use ducting,at least part of the way  to make it neat and tidy 

@scottishjohn if you look carefully you will see there is 50x50 trunking already installed all around the cabinet. Where it's needed I have installed it.

 

As for running cable in conduit, you still have to put the conduit somewhere. If that "somewhere" is in the EPS then it will still derate the cable, albeit not quite as badly. From recollection (I don't have the 7671 guide at home, cos it's living at site at the mo) clipped direct gives 27A limit, in conduit in EPS would give 18.5A or thereabouts (although some argue that the derating isn't valid if you're talking about conduit that is also touching the plasterboard, the regs don't give a firm steer either way so I play safe). 

 

Besides which, the lifetime of the mains cable for sockets (which is all that I am chasing into the EPS anyway) is probably longer than my remaining years on this planet, and sockets don't tend to need additional cables pulled 😁

Share this post


Link to post
Share on other sites
5 minutes ago, Nelliekins said:

@scottishjohn if you look carefully you will see there is 50x50 trunking already installed all around the cabinet. Where it's needed I have installed it.

 

As for running cable in conduit, you still have to put the conduit somewhere. If that "somewhere" is in the EPS then it will still derate the cable, albeit not quite as badly. From recollection (I don't have the 7671 guide at home, cos it's living at site at the mo) clipped direct gives 27A limit, in conduit in EPS would give 18.5A or thereabouts (although some argue that the derating isn't valid if you're talking about conduit that is also touching the plasterboard, the regs don't give a firm steer either way so I play safe). 

 

Besides which, the lifetime of the mains cable for sockets (which is all that I am chasing into the EPS anyway) is probably longer than my remaining years on this planet, and sockets don't tend to need additional cables pulled 😁

 

Snapshot of the rating table from the OSG for the 18th:

 

image.png.e2bac0fc93465ca793aa6dede9085f97.png

  • Like 1

Share this post


Link to post
Share on other sites

the original post was about problems of insulation degrading  in cable due to touching foam 

and my term "duct " was a generic one ,as in meaning something the wires go inside .

there are many ways to do it 

Share this post


Link to post
Share on other sites
3 hours ago, JSHarris said:

Plastic electrical conduit (as distinct from duct) is usually made from uPVC or sometimes ABS, so that it can be solvent welded.

 

I'd not seen the distinction  of cable ducting vs conduit called out before (I had probably used them interchangeable) so thanks for this. I want to build in ability to re-cable certain things -- mostly A/V and, bizarrely, but thanks to current state of smart home tech, the light switches -- so knowing whether I'm looking for conduit vs duct to be chased into walls or burried in voids is most helpful.

 

Share this post


Link to post
Share on other sites
1 hour ago, scottishjohn said:

the original post was about problems of insulation degrading  in cable due to touching foam 

and my term "duct " was a generic one ,as in meaning something the wires go inside .

there are many ways to do it 

 

Totally agree. I chose to chase out the EPS with a DIY hot knife and use 6242B cable, derating sufficiently according to 17th edition (which was in effect when my cabling install was designed). I have since been told by the sparky who fitted our solar panels that he'd have put electrical conduit in, so that seems like the "Pro" solution. 

 

👍

Share this post


Link to post
Share on other sites

Firstly is this 6242B cable ok to be put directly in contact with EPS without risk to either? Have I got that correct? Also does the same code apply to things like speaker cable, cat 5/6/7  etc?

In terms of cost balance does it make just as much sense to use something like the product in the link below and just use the cheaper cable?. How about back boxes for electrical sockets for sockets AND light switches. What should they be made from? This is not an area I had been aware of before..

https://www.tlc-direct.co.uk/Products/LFLS20slash10.html?source=adwords&ad_position=&ad_id=315107931576&placement=&kw=&network=u&matchtype=&ad_type=&product_id=LFLS20%2f10&product_partition_id=576185600542&version=finalurl_v3&gclid=Cj0KCQjwgLLoBRDyARIsACRAZe6IukJUky8zEwQqnQ8dgK3dlRp052P2gJTBFp8EePPY8cpN66l1TswaAoRhEALw_wcB

 

 

Share this post


Link to post
Share on other sites

My understanding is that 6242B has improved fire performance (low smoke) compared to 6242Y. I believe that means they can't use PVC for the insulation but I don't know if the insulation they do use means it's ok to put in contact with EPS.

Share this post


Link to post
Share on other sites

gotcha @Temp, thanks. So does metal conduit/sheathing/whatever anyone wants to call it, solve the issue? Is stuff like polybutylene pipe for water, or whatever other material might be used, an issue in the same respect?

Share this post


Link to post
Share on other sites

PVC covered wire should not be in contact with EPS. Has caused at least one fire...

 

https://www.esfrs.org/black-museum/all-the-black-museum-cases/pvc-cable-insulation-and-polystyrene-insulation/

 

Over a period of years the cable insulation became coated in polystyrene, not due to thermal effects but rather as a result of “plasticiser migration”.



 

There was a reaction between the plasticiser in the PVC insulation and the polystyrene, whereby the plasticiser migrated out of the PVC, softening the styrene which adhered to the PVC, leaving a brittle cable that cracked and split, exposing live conductors which caused a fire involving the timbers within the loft space.

 

 

Share this post


Link to post
Share on other sites
22 minutes ago, Big Neil said:

gotcha @Temp, thanks. So does metal conduit/sheathing/whatever anyone wants to call it, solve the issue? Is stuff like polybutylene pipe for water, or whatever other material might be used, an issue in the same respect?

 

Metal is ok. Don't know about polybutylene pipe. When I was developing electronic products we used polyethylene bags to keep mains leads away from EPS packaging until that was replaced by cardboard.

Share this post


Link to post
Share on other sites

Sorry I think I double posted. Bit fiddly this phone.

Share this post


Link to post
Share on other sites

From this thread...

 

https://forum.buildhub.org.uk/topic/1970-migration-of-plasticizers-from-pvc-cables/

 

comes..

 

https://www.voltimum.co.uk/articles/q-day-are-pvc-cables-still-damaged

 

Today's PVC cables will still degrade when in contact with expanded polystyrene insulation.



Zero halogen cables, such as Draka's Saffire OHLS wiring cables, do not react with polystyrene, but current ratings should be reduced as per BS7671:2008 Regulation 523.7. 

 

 

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now