Green Building Forum - EPS and PVC cables Sat, 02 May 2026 11:54:58 +0100 https://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 EPS and PVC cables https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=294888#Comment_294888 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=294888#Comment_294888 Sat, 19 Feb 2022 20:49:03 +0000 tony
There is no evidence that this is dangerous as only a small portion of the plasticiser is lost and only from the outer sheath of the cable. The polystyrene is thinned a tad.

Is anyone aware of a resulting problem?]]> EPS and PVC cables https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=294889#Comment_294889 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=294889#Comment_294889 Sat, 19 Feb 2022 22:09:39 +0000 fostertom EPS and PVC cables https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=294890#Comment_294890 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=294890#Comment_294890 Sat, 19 Feb 2022 22:42:40 +0000 tony EPS and PVC cables https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=294894#Comment_294894 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=294894#Comment_294894 Sun, 20 Feb 2022 01:48:48 +0000 Mike1 Posted By: tonyIs anyone aware of a resulting problem?
I seem to recall that the plasticisers used were changed years ago (70s?) to reduce the problem.

Posted By: tonyIn the process if a gap forms the process stops.

...however if the cable was loose-laid on polystyrene - in a loft, for example - the cable may move as the polystyrene shrinks back. Or if the polystyrene becomes sticky, as it might, it could stick to the cable. Either could prevent the process stopping, in theory.

It would be interesting to see if anyone has any real-world fire reports though.]]> EPS and PVC cables https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=294896#Comment_294896 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=294896#Comment_294896 Sun, 20 Feb 2022 08:07:12 +0000 tony EPS and PVC cables https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=294899#Comment_294899 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=294899#Comment_294899 Sun, 20 Feb 2022 08:17:55 +0000 Nick Parsons EPS and PVC cables https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=294907#Comment_294907 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=294907#Comment_294907 Sun, 20 Feb 2022 10:35:27 +0000 bhommels
4 years on (and counting),the cable is still fine. I can take it out, it is not sticky and I can bend it around without evidence of any cracking of the outer sheath.

I am definitely not denying that the effect plays a role. As Tony says, it is likely driven by diffusion and that is strongly temperature dependent. My shed is shaded and does not get very hot in summer, it gets humid in winter, and is probably not the ideal site for accelerated tests, the timescales could be very long.

I have installed conduits around all (but two!) cables in contact with EPS as I think it is good practice in any case. Better be safe than sorry.

One bit of additional information that could be related: when trying to get my leftover graphite EPS recycled, one plant refused to take it on the grounds that it was produced before a certain year, and thus might contain a compound of which I forgot the abbreviation. If this compound has a high diffusion constant for common cable plasticizer it could be responsible for the effect. Then, it might not :-)]]> EPS and PVC cables https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=294937#Comment_294937 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=294937#Comment_294937 Mon, 21 Feb 2022 12:58:38 +0000 owlman EPS and PVC cables https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=294938#Comment_294938 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=294938#Comment_294938 Mon, 21 Feb 2022 13:20:34 +0000 tony EPS and PVC cables https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=294939#Comment_294939 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=294939#Comment_294939 Mon, 21 Feb 2022 14:34:37 +0000 owlman

https://www.buildmagazine.org.nz/assets/PDF/BUILD65-26-ElecCableInPoly.pdf]]> EPS and PVC cables https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=294940#Comment_294940 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=294940#Comment_294940 Mon, 21 Feb 2022 16:57:49 +0000 tony
The last point about cable sizing may be the most important.]]> EPS and PVC cables https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=294941#Comment_294941 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=294941#Comment_294941 Mon, 21 Feb 2022 17:20:05 +0000 djh
3. Don’t use EPS beads: Loose-fill EPS beads
(‘beans’) must not be used as insulation since these
could potentially maintain permanent contact with
the cable (since gravity would keep moving new
beads into contact with the cabling).

That seems a bit over-protective. Firstly in many installations the beads are coated with glue so even when loosed-filled they won't move about afterwards. Secondly even if they can move they won't achieve anything near to close contact over the whole surface of the cable since there is in theory just a single point of contact between each bead and the cable. So I'd expect a lot less trouble than in many other circumstances.]]> EPS and PVC cables https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=294942#Comment_294942 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=294942#Comment_294942 Mon, 21 Feb 2022 18:10:04 +0000 revor Posted By: tonyThe last point about cable sizing may be the most important.

BS 7671 17th edition 523.9 state that cables should not be installed in situations where they are possibly covered in insulation. If there is a situation where it unavoidable up to 500 mm is allowed for which there is a sliding scale derating factor for the cable depending on the length surrounded from 50 mm to 400 mm. 500mm and above of cable in insulation the cable is derated by 0.5 i.e. only allowed to carry half the current of that cable when clipped in the open.
So bottom line don't cover with insulation.
I can find no reference in there for EPS specifically.]]> EPS and PVC cables https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=295065#Comment_295065 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=295065#Comment_295065 Fri, 04 Mar 2022 07:31:16 +0000 TimSmall EPS and PVC cables https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=299752#Comment_299752 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=299752#Comment_299752 Thu, 19 Jan 2023 18:56:57 +0000 wookey EPS and PVC cables https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=299754#Comment_299754 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=299754#Comment_299754 Thu, 19 Jan 2023 19:48:57 +0000 Jeff B EPS and PVC cables https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=299755#Comment_299755 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=299755#Comment_299755 Thu, 19 Jan 2023 20:03:15 +0000 djh Posted By: wookeyInteresting thread. I had assumed that eventually the PVC got brittle (probably took decades), but the info here suggests probably not.Dunno. I do remember seeing old rubber-insulated mains cables in a cellar that had become so brittle that pieces just flaked off with very little provocation. But PVC is different, I think. I mean UPVC windows aren't especially brittle are they?]]> EPS and PVC cables https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=299756#Comment_299756 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=299756#Comment_299756 Thu, 19 Jan 2023 20:04:43 +0000 djh Posted By: Jeff BWhat about the situation when IWI is applied onto a plastered wall and the electrical cable is buried in the cement render behind the plaster? Does that have an effect on the current carrying capacity of the cable?Not particularly, because plaster and cement are reasonably good conductors of heat. Plus the cables are often covered with a metal protective strip that's an even better conductor.]]> EPS and PVC cables https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=299760#Comment_299760 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=299760#Comment_299760 Thu, 19 Jan 2023 21:42:25 +0000 tony EPS and PVC cables https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=299761#Comment_299761 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=299761#Comment_299761 Thu, 19 Jan 2023 22:37:04 +0000 Jeff B Posted By: djh
Posted By: Jeff BWhat about the situation when IWI is applied onto a plastered wall and the electrical cable is buried in the cement render behind the plaster? Does that have an effect on the current carrying capacity of the cable?
Not particularly, because plaster and cement are reasonably good conductors of heat. Plus the cables are often covered with a metal protective strip that's an even better conductor.

That's my feeling too. I think applying IWI should make the wall cooler which would enhance conduction of heat away from the cables.]]> EPS and PVC cables https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=299786#Comment_299786 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=299786#Comment_299786 Fri, 20 Jan 2023 21:12:16 +0000 djh Posted By: Jeff BThat's my feeling too. I think applying IWI should make the wall cooler which would enhance conduction of heat away from the cables.It will actually reduce the conduction, because it increases the average insulation value, but it would start from a lower base (as long as there's no CWI or EWI as well) so sums would have to be done.]]> EPS and PVC cables https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=299794#Comment_299794 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=299794#Comment_299794 Sat, 21 Jan 2023 13:26:17 +0000 bhommels Posted By: wookeyInteresting thread. I had assumed that eventually the PVC got brittle (probably took decades), but the info here suggests probably not. Is there an equilibrium between the cable sheath and the EPS or will all the plasticiser move eventually, if they stay in contact?
Assuming it is diffusion driving the process, 'all' the plasticiser will move into the EPS.]]> EPS and PVC cables https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=299802#Comment_299802 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=299802#Comment_299802 Sat, 21 Jan 2023 22:07:37 +0000 tony
EPS has so little mass that it can’t absorb all the plasticiser in the pvc.

If there was a problem we would know about it by now, eps and pvc cables have been in close proximity for 40 years or more, touching and no reported incidents.]]> EPS and PVC cables https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=299806#Comment_299806 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=299806#Comment_299806 Sun, 22 Jan 2023 15:14:42 +0000 Mike1 Posted By: tony eps and pvc cables have been in close proximity for 40 years or more, touchingIt would be interesting to know to what extent that's the case. I've seen odd examples from retrofit cavity wall insulation but, at least for UK new-build housing under the NHBC, EPS & PVC cables are banned from coming into contact, and it's such a commonly known and warned-about 'issue' that it's probably infrequently done elsewhere.

However from what I've read, with modern cables the risk seems to be more theoretical than real, and is probably confined to unrestrained cables that are subject to movement.]]> EPS and PVC cables https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=299807#Comment_299807 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=299807#Comment_299807 Sun, 22 Jan 2023 15:45:58 +0000 tony EPS and PVC cables https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=299808#Comment_299808 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17397&Focus=299808#Comment_299808 Sun, 22 Jan 2023 16:54:42 +0000 revor