Concerned about cabling running behind polystyrene plasterboard

Discussion in 'Electrics UK' started by swaring, 23 Oct 2020.

  1. swaring

    swaring

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    Hi there,

    I hope someone can give me advice. I had my garage converted by a so called professional builder.

    he has battened a breeze block cavity and put polystyrene backed plasterboard onto the battens before plastering. Please see images attached. The electrician drilled through the battens beforehand and did all the wiring. He didn’t use conduit. The polystyrene plasterboard the was fixed to the battens. Is this safe? And should building regulations of flagged this?
     

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  3. DetlefSchmitz

    DetlefSchmitz

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    Only issue I can think of is if the wire is not run in safe zones. Do you have a before plasterboard picture?
     
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  4. swaring

    swaring

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    I don’t unfortunately. The wires were run through holes in the battening. With it being polystyrene backed plasterboard with this cause problems with the wiring if it’s not in conduit?
     
  5. DetlefSchmitz

    DetlefSchmitz

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    I believe it is fine. Although it's hard to match with an official installation method. Putting it in conduit only decreases the current carrying capacity. All the standard methods will allow at least 20A, which is what is required.
     
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  6. swaring

    swaring

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    Oh I just thought you couldn’t run electric cables behind polystyrene backed plasterboard.
     
  7. DetlefSchmitz

    DetlefSchmitz

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    Ah. So that's your concern. I don't know enough about the type of polystyrene used to give a useful opinion on that. I guess it also depends on whether it's touching, and whether there is any protective film on the back. Do you have a manufacturers id of the boards used?
     
  8. swaring

    swaring

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    I don’t know what the builders used. There is the same amount of polystyrene to plasterboard and there seems to be a silver foil inbetween the 2 substrates.
     
  9. DetlefSchmitz

    DetlefSchmitz

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    OK - doesn't sound too great. Of course, without photos you don't know if the builder added any protective barrier. Probably not. It's beginning to sound as though you need to ask him some carefully worded questions. Maybe withhold payment till you are satisfied with the answers?
     
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  11. JohnW2

    JohnW2

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    As I understand it, there is a potential problem with PVC cables being in direct contact (no intervening film/whatever) with at least some types of expanded polystyrene. Is that no the case?

    Kind Regards, John
     
  12. DetlefSchmitz

    DetlefSchmitz

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    Yes. And it looks like this may be the situation in this case.
     
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  13. swaring

    swaring

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    So the electrics have been wired directly to my fuse box with 2 new RCDs I think they are called. 1 for lighting and one for sockets. Should this polystyrene plasterboard have been passed off by building regs?
     
  14. JohnW2

    JohnW2

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    You won't find anything in the Wiring Regulations specifically about polystyrene and cables, but there is plenty about protecting cables from environmental hazards - so if the cables are in direct contact with the polystyrene, there could be a problem.

    Did a LA building inspector actually inspect the work and, if so, did he/she actually see/know what was going on behind the visible surface iof the plasterboard?

    Kind Regards, John
     
  15. swaring

    swaring

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    I really don’t know. The builder used a private Building Regulations company and I have a certificate. Is this something I can call them out on? I’m really concerned now of a fire being caused.
     
  16. JohnW2

    JohnW2

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    It would seem that your problem is that unless you rip out some of the plasterboard, you don't really know whether or not there is anything to "call them out" about, do you?

    Kind Regards, John
     
  17. swaring

    swaring

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    To be honest I employed a builder who had amazing reviews to do a pretty simple job. I didn’t expect to be checking up on a qualified builders work. That’s his job at the end of the day. But if it’s going to affect the lives of my family then I will do what it takes to get this resolved. I seen the electrician do the first fix. He drilled holes through the stud wall and fed cables through. The builder then put these cheap polystyrene plasterboard panels on and plastered. The electrician can e out to do the second fix knowing polystyrene plasterboard was used.
     
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