What Polystyrene can do to PVC

[Guitarist]

Took this photo a few days ago. Lots of cabling had been affected where several years ago the "cavity wall people" had blown insulation and it had found its way into the meter box.

 

[PC Electrics]

I rewired a kitchen extension a few years ago where all the cables in the loft were completely wrecked because the DIYer who built it used ps sheets instead of rockwool!!!

 

[SirKit Breaker]

This is a classic reason why we should never use expanding foam near cables.

Cheers.........Howard

 

[PC Electrics]

Expanding foam isn't polystyrene. Its usually epp (expanded poly propylene), which is harmless to PVC.

 

[Guitarist]

Just checked a can I have and it's Polyurethane.

 

[Top Cat]

Just wired a new house that was made from polystyrene blocks that are filled with concrete.

I had to use oval conduit to keep it away from polystyrene and LSF cable.

What a bitch using LSF.

 

[DPG]

A lot of people don't realise why the mains cables are in bags when appliances are supplied in polystyrene block packaging. They realise when they get it back out a few years later and they haven't bothered bagging it! Daz

 

[Engineer54]

Your all talking about bygone years, the modern day stuff they use in roof fill insulation with the BS Kite Mark has no affect on PVC cables or pipework, and hasn't done for some years now!! The problem stuff was last used in and around the 70's, so there will still be a good amount of that older stuff about for many years to come!! All the modern blown polly, whether it be in sheet form or balls has been chemically changed to stop the platicising effect to PVC cables and the like!!!

 

[Guitarist]

The cable I showed in the first post had the insulation balls blown into the cavity in the late 80's so looks like it may be around for even longer...

 

[DPG]

Interesting point raised about the all insulation. Is some of this stuff polystyrene? If so, how many houses with tails run in the cavities have had this done? Daz

 

[Guitarist]

I would suggest that thousands of houses have tails running from outside meter boxes through cavities which were insulated with polystyrene balls back in the 70's and 80's.

 

[DPG]

That's what I was thinking. All those cables getting eaten away over the years. Bearing in mind the PVC/polystyrene issue has been known about for such a long time, it makes you wonder how they ever thought it was Ok to do it. Daz

 

[cymroaur]

A friend of mine has just bought a house with t&e run in the cavity and polystyrene balls blown in at some point. What advice should I give him? Do I do an IR test every few months to keep an eye on things, or tell him to rewire? Since he's re-decorating I could chase the walls etc, but the painter's already done two rooms!

 

[brman]

A friend of mine has just bought a house with t&e run in the cavity and polystyrene balls blown in at some point. What advice should I give him? Do I do an IR test every few months to keep an eye on things, or tell him to rewire? Since he's re-decorating I could chase the walls etc, but the painter's already done two rooms!

can't you inspect at the top of walls and the back of sockets etc?

 

[Marvo]

I've seen a few cables over the years with insulation visibly damaged by polystyrene but never to the extent of a conductor being exposed or it having an effect on an IR test or causing a fault.