Cable and insulation

[SJRSJR]

Hello

I want to put some rolls of insulation in the ceiling void between the kitchen and the bedroom above, primarily to dampen the clatter in the kitchen.

The lighting cable is currently lying loose. What is the best way to ensure the cable won’t overheat.

At some point the kitchen will have downlights so it will be difficult to put the cable on top of the insulation

I’ve been looking at perforated cable trays but they don’t look very deep. Would that be sufficient? Thanks

 

[Murdochcat]

I think you need to decide on the downlighting and fit them BEFORE you deal with insulation

Just saying

 

[EFLImpudence]

The lighting cable is currently lying loose. What is the best way to ensure there cable won’t overheat.

It won't.

If you have a 6A lighting circuit then the cable will be so over-rated that it already exceeds the 50% maximum derating for being in thermal insulation.

 

[SJRSJR]

Murdochcat - the kitchen will be renovated next year. I have a rough idea so I planned to put cable in position but the layout may change so I don’t want to start fitting them now.

EFLImpudence - It is 6A and the cable is solely for the kitchen lights, the other downstairs lights are on a separate circuit. So that’s good to know, thanks.

 

[JohnW2]

It won't. ... If you have a 6A lighting circuit then the cable will be so over-rated that it already exceeds the 50% maximum derating for being in thermal insulation.

Quite so. I often wonder why people often fuss about 6A lighting circuit cables 'in insulation'. As you say, even with 1.0mm² cable (let alone the commonly (but unnecessarily)-used 1.5mm²) cable, the current-carrying-capacity is well above 6A even with the maximum possible 'de-rating' factor due to the insulation.

 

[endecotp]

Make sure that the cables are all only lights. You don’t want to accidentally bury the cooker supply in insulation.

For soundproofing, acoustic insulation is of course better than regular “loft roll”.

 

[SJRSJR]

Thank you all. Great advice, much appreciated.

 

[SJRSJR]

Make sure that the cables are all only lights. You don’t want to accidentally bury the cooker supply in insulation.

Having lifted more board, there are 2.5mm cables, for the bedroom sockets and the kitchen sockets (two separate circuits). No cooker cable, it’s gas.

Having searched a few posts, someone proposed laying plasterboard over their cable (which is already lying on the plasterboard), thereby allowing heat to dissipate via the plasterboard.

Is that adequate or should it be de-rated? Thanks.

 

[EFLImpudence]

Having lifted more board, there are 2.5mm cables, for the bedroom sockets and the kitchen sockets (two separate circuits). No cooker cable, it’s gas.

Having searched a few posts, someone proposed laying plasterboard over their cable (which is already lying on the plasterboard), thereby allowing heat to dissipate via the plasterboard.

Is that adequate or should it be de-rated? Thanks.

Mmm. Not sure - assuming it is a 32A ring circuit, the cable would be alright anyway with not more than 100mm. of insulation.

The plasterboard would seem to be better than that.

 

[SJRSJR]

Thanks. It’s a deep void so I was going to put 200mm on top of 100mm sound insulation. (I’ve since read that it was a waste of time when others did it)

When you say ‘better than that’ do you mean better than just having it under the insulation?

 

[EFLImpudence]

When you say ‘better than that’ do you mean better than just having it under the insulation?

Yes, it seems to me to be better than covered by the insulation.

A ring circuit cable is allowed to be "enclosed in conduit in an insulated wall".

 

[SJRSJR]

Thanks. I could also try to enclose it in plastic trunking but it’d be a lot easier to just lay plasterboard over it.

 

[EFLImpudence]

Yes, I think the plasterboard would be better. That was my point.