polystyrene beads and electrical cable twin and earth

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Last year I had a new consumer unit fitted in the downstairs hall by my electrician. He also installed some other lighting, checked all the sockets, and checked some work I did before certifying all of the work. This year I'm about to fit new wood laminate floor to the upstairs hall. I had a look under the boards and some birds had built a nest above the place the consumer unit was! Well, I cleared that out, but the polystyrene beads from the cavity wall insulation had poured in due to the birds making a hole into the cavity. Now I've got some ugly looking cables and a few bits of polystyrene left. Will the polystyrene attack it further? Should I get my electrician back to replace all the cables? I added some photos.
Thank you in advance for your responses.



 
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The cables need to be replaced. The polystyrene causes the plasticiser in the PVC insulation to migrate out of the cable, which is what the sticky mess is, and this results in the cable insulation becoming brittle and cracked.
 
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They're pretty disgusting, aren't they? - Looks like some kind of mould.

Need to replace them, and the ones that look OK but disappear into the netherworld need to be traced and checked along their lengths....
 
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I'm not so sure.....
In our loft, there are thin (eg 10-12mm) polystyrene sheets laid on top of the plasterboard. In places where there are cables laid on top of it, and especially where there is also glassfibre insulation on top :eek: , it would appear that the cable has "melted" into (and right through) the polystyrene. It's the polystyrene that has gone, not the pvc. Could it also be something to do with heat?
I just wonder if you couldn't use a mild solvent to clean the polystyrene off the pvc. Or maybe not such a mild solvent, like acetone or petrol. I should try it on a piece that will be easy to replace, just in case it all starts to dissolve.... maybe that bit with the insulating tape on.
 
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The polystyrene hasn't really gone - it's just occupying a lot less volume than it did before, and it won't have just made the PVC cable sheath a bit grubby and sticky - it will have leached out the plasticiser and rendered it unfit for purpose.

Needs to be replaced.
 
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I'm not so sure.....
In our loft, there are thin (eg 10-12mm) polystyrene sheets laid on top of the plasterboard. In places where there are cables laid on top of it, and especially where there is also glassfibre insulation on top :eek: , it would appear that the cable has "melted" into (and right through) the polystyrene. It's the polystyrene that has gone, not the pvc. Could it also be something to do with heat?

pvcpoly.jpg
 
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How do you know it's not a 2.5 clip on 1.5 or 1.0mm cable?
Or have you been busy playing with your scale rule?

Anyway, one day when I've had enough to drink, I'm going to take a selection of (highly flammable) solvents into the loft and try them out on some of my sticky cables to see what happens (apart from putting my foot or more through the ceiling.)
Since mine have been there for at least ten years, do you think they might just snap like breadsticks?
 
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I'm not so sure.....
In our loft, there are thin (eg 10-12mm) polystyrene sheets laid on top of the plasterboard. In places where there are cables laid on top of it, and especially where there is also glassfibre insulation on top :eek: , it would appear that the cable has "melted" into (and right through) the polystyrene. It's the polystyrene that has gone, not the pvc. Could it also be something to do with heat?
I just wonder if you couldn't use a mild solvent to clean the polystyrene off the pvc. Or maybe not such a mild solvent, like acetone or petrol. I should try it on a piece that will be easy to replace, just in case it all starts to dissolve.... maybe that bit with the insulating tape on.
 
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I hope to God you're being ironic! If not please temper your wit! There are enough idiots out there without encouraging another one to strip the insualtion off his cable using nitromors by candlelight!!
 
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Ah! that would explain why the average Pole tries to wire a lighting cicuit like a ring!!
 
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Thanks for all of your comments. I have my electrician coming on the 23rd to replace all those ugly looking cables. On the ones that come out, I'll try the solvent on them before binning them and post back to this forum.

Where the cable has landed on a sheet of polystyrene (above posting) I think that presents a bigger risk of fire, since there's more styrene about to react with the PVC. I believe what happens is the plasticiser is pulled out of the PVC, leaving it quite brittle. So, in a few years, with a some movement in the loft, you could be looking at a break in the cable.

I found this document from Ireland's Electrical Contractors Safety & Standards Association which you might find useful:
http://ecssa.ie/newsletters/35_Spring 06 Newsletter .pdf
 

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