Running cables over plaster board with insulation

[JasonTR]

Hi all,

My ceiling (ground floor) was made of lath and wet plaster. It has recently fallen and I would like to use this opportunity to fill the gaps between the joists with insulation and cover it all with plasterboard. There are quite a lot of cables in there already some old some new. I am wondering if the insulation is going to make the cables be hotter and if there are any regulations I should follow. The cables are not in any conduits and some are for the lights some are for the sockets there is one quite thick going to the kitchen most probably for a cooker.

Question is Electrical cables and Floor insulation over plasterboard, do they mix well and can they live together happily

Thanks

 

[EFLImpudence]

Yes, the cables will get warmer.

It will make no difference to the lighting circuits as they are well under capacity.

However, the cooker and socket circuits could be damaged.

Assuming you have standard circuits - 32A for sockets and cooker with 6mm² cable for cooker - the tables state that if the thermal insulation is not more than 100mm. on top of the cables they would still be satisfactory.

You must not have any of the cables totally surrounded by the insulation.

 

[ban-all-sheds]

You must not have any of the cables totally surrounded by the insulation.

The lighting ones will be OK, assuming it's a 6A circuit.

 

[PrenticeBoyofDerry]

I am wondering if the insulation is going to make the cables be hotter

Yes they will

and if there are any regulations I should follow.

Yes there is BS7671:2008 Appendix 4
http://www.shepleyelectricalservices.com/Installation Method Codes.pdf

Question is Electrical cables and Floor insulation over plasterboard, do they mix well and can they live together happily

They can live happily together, providing the de-rating factors are applied to the cable's current carrying capacity, if the cable is undersized, the CSA will need increasing ,to a size that will allow current to pass safely.

 

[ban-all-sheds]

Yes there is BS7671:2008 Appendix 4
http://www.shepleyelectricalservices.com/Installation Method Codes.pdf[/QUOTE]
And to go with that (which is just a summary of part of Appendix 4):

http://www.batt.co.uk/upload/files/4d5.pdf

which is also only a subset.

Jason - please note what both of them say about needing access to the whole of Appendix 4, which is only possible by obtaining a copy of the Wiring Regulations.

If you want to make the decisions about what cables to use, you have no choice but to get a copy and learn how to use it.

 

[JohnW2]

If you want to make the decisions about what cables to use, you have no choice but to get a copy and learn how to use it.

I don't think there's a question of him "deciding what cables to use", since the cables are already there, and I very much doubt that he intends to replace any. His question is therefore about whether or not he can safely "take the opportunity" to add the insulation when the ceiling is boarded. If the answer were no (and, as EFLI has said, it probably isn''t), I imagine he would forget the insulation, not replace the cables.

I also wonder why he's even thinking about insulation above a ground floor ceiling - Jason:, is this ceiling perhaps in a bungalow or a single story extension?

Kind Regards, John

 

[drgl]

I also wonder why he's even thinking about insulation above a ground floor ceiling - Jason:, is this ceiling perhaps in a bungalow or a single story extension?

Kind Regards, John

Noise?

 

[JohnW2]

I also wonder why he's even thinking about insulation above a ground floor ceiling - Jason:, is this ceiling perhaps in a bungalow or a single story extension?

Noise?

Possibly - we need to wait for him to tell us. If you're right, and if he were thinking of standard thermal insulation, that's pretty disappointing in terms of sound.

Kind Regards, John

 

[PrenticeBoyofDerry]

If sound, he can avoid using thermal insulation and fit sound bloc to the ceilings

 

[JohnW2]

If sound, he can avoid using thermal insulation and fit sound bloc to the ceilings

He could, but we need to wait for clarification of what sort of insulation he is contemplating, and why.

Kind Regards, John

 

[JasonTR]

Guys thank you for the replies. Yes I was thinking about the noise but not only. It is in a 3 bed semi-detached house but it is draughty. It is a 1930's house which has air bricks and a fireplace in each room. I think that putting insulation might make it a bit warmer. And you are correct I am not looking to touch the cables they are already there do not want to start replacing them. They look fine

 

[ban-all-sheds]

It is in a 3 bed semi-detached house

Cavity walls, or solid?

but it is draughty.

That's how they were built.

Be prepared for significant condensation and mould if you manage to get rid of all the draughts unless you are prepared to stop cooking, washing, showering/bathing and breathing.

It is a 1930's house which has air bricks and a fireplace in each room. I think that putting insulation might make it a bit warmer.

Notwithstanding the above, what you need to do is to stop the outside air getting into the floor voids. Check on the Building forum, but I don't think there should be airbricks leading into first floor voids. Ground and first floor rooms, and voids under the ground floor yes, but not under the first floor.