Cables above or below acoustic insulation

[tommyleestaples]

I need to run lighting cables for the ground floor lights in the ceiling. I will be doing this from below. The void between the two floors will also be filled with 100mm acoustic insulation. Should the lighting cables sit above or below the acoustic insulation. 

[Beau]

I was just chatting with our sparky about this as I was laying in some cables last week. My question was did I need to clip the cables or was it OK to lay the cables over the insulation. He was happy with them laid on top of the insulation. I suspect that if they were laid on the plaster board with insulation over the top they could heat up up lessening their current carrying capacity.

[tommyleestaples]

Thanks for your reply Beau. I have used 1.5mm T&E and they are only LED spotlights. Could of prob got away with 1mm.

 

So sounds like cables first, then insulation with cable coming through the insulation to the individual spot lights 

[nod]

It doesn’t really make any difference 

Acoustic or none acoustic It just stops the sound bouncing around 

 

Putting insulation between floors of a domestic house seems to be dying out most my jobs with Architects preferring to let the heat rise 

 

[ADLIan]

100mm mineral wool insulation is often used between joist for acoustic insulation in intermediate floors within dwellings - see Appr Doc E. Some plasterboard & I-joist manufacturers have systems that comply with the Regs without the need for this insulation. The insulation will also have thermal properties but this is irrelevant here. An electrician will be able to advise but I believe good practice is to clip the cable to the sides of the joist above the insulation. Cables under the insulation may need de-rating but this may not be too much of an issue with lightly loaded lighting circuit cables.

[Spinny]

Depends where you plan to put the acoustic insulation. In this case it is the other way round because I am trying to muffle rain noise from a warm roof, and I wanted to keep the acoustic insulation above the downlights.

[G and J]

10 minutes ago, Spinny said:

Depends where you plan to put the acoustic insulation. In this case it is the other way round because I am trying to muffle rain noise from a warm roof, and I wanted to keep the acoustic insulation above the downlights.

What’s your warm roof made of?

[Spinny]

4 minutes ago, G and J said:

What’s your warm roof made of?

It is a single ply membrane adhered to 150mm PIR with a roof felt under onto a plywood deck.

Specified by the architect who seemed surprised when I said it can be like a drum in heavy rain.

Sound people told me the plaster board ceiling will not be much help once I puncture it with downlights and speakers.

[G and J]

5 hours ago, Spinny said:

It is a single ply membrane adhered to 150mm PIR with a roof felt under onto a plywood deck.

Specified by the architect who seemed surprised when I said it can be like a drum in heavy rain.

Sound people told me the plaster board ceiling will not be much help once I puncture it with downlights and speakers.

Oh my word. That was exactly our plan, except I’m not keen on needing ear defenders if it rains!

[Super_Paulie]

I used what is called "method 100” and "101" for my cables between floors.