Loft Insulation and wiring!

Bexm

Hello

We are in the process of laying some more loft insulation in the hope that it may keep our freezing house a little bit warmer but we have a question that I thought one of you may be able to help with?

There was already some insulation laid but it looks like there were mice at one time as half of it has gone and the rest is shreaded. There is a small junction box with about 5 wires coming out of it screwed to the floor that powers the lights in our bathroom and various other things.

My fiance says its fine to lay the fibreglass over this, as it looks like the previous stuff was, but I am not so sure as I think its a fire hazzard?

What should we be doing?

Thanks in advance for your help.

Bex

cattie

My understanding is that insulation should not be laid over wiring. It might be an idea to just leave a space around the junction box.

espresso

There is no problem laying fibreglass insulation over wiring including junction boxes.

Bexm

hmmm two different replies now..!
Anyone else? So I have a third opinion?

cajef

As stated by espresso and your fiancé, it is perfectly alright to lay fibreglass over cables and junction boxes, that is how most builders etc. would do it.

Bexm

Thanks for the info guys! Just making sure we weren't going our burn our house down!
Espresso sorry if it sounded as if I didnt believe you.. but its difficult to know when there are only two answers and they are both different!:)

jimbo_the_jetset

cajef wrote: »

As stated by espresso and your fiancé, it is perfectly alright to lay fibreglass over cables and junction boxes, that is how most builders etc. would do it.

To do what a builder would do doesn't make it safe.

I think you will find most 'informed' people recommend not to insulate over electrical wiring. Electrical wiring can create amounts of heat, if you insulate over this you are making it hotter!! And more susceptible to start a fire. Furthermore if you need to access the wiring for any reason you won't have to lift the insulation to get to it.

Also see here :

http://www.simplifydiy.com/walls-and-ceilings/ceiling-insulation/loft-insulation

http://www.diydata.com/projects/loft_insulation/loft_insulation.php

cajef

jimbo_the_jetset wrote: »

I think you will find most 'informed' people recommend not to insulate over electrical wiring.

Hmm, well I stand corrected, having said that there must be a hell of a lot of houses that are in danger of burning down.

I can understand that heat can be generated by cables, usually only by incorrect load or loose connections, I would have thought that this is a very small risk but I can see the reasoning behind it.

jimbo_the_jetset

Yes, mine is one of them. Noticed yesterday that part of my lighting loop is connected with plastic electrical connectors (I assume 13A ones!!) wrapped in insulation tape sat under insulation. I'll be replacing that as soon as poss with a 20A junction box and checking the rest of the wiring.

p.s. another note (as I had this in my house) if you have an electrical shower it probably runs on 45-50amps. If this is under insulation it WILL generate loads of heat and will be more dangerous that the lighting circuit.

If you can't be good, be safe!

(p.s. I'm not a spark so don't take my word as gospel, if in doubt get a pro to do the work)

eightpints

The letter of the law is that cables should be clipped to the top joists to avoid them being covered by insulation.
However it is generally lighting cables in roof spaces which won't be drawing excessive currents so they will be fine.
A shower does use lots of energy, however this is usually only for a short period (the duration of your shower).
So I would insulate over them, but if you have a shower, you could pull the insulation to one side of the cable if you want, but I doubt it would be a problem.

Bexm

Yeek.. so many mixed replys..! I can hear an "I told you so" coming from my fiance soon.. but have done some googling my self and most places say don't insulate over wiring.. hmmm