ceiling insulation

[Garth]

dumb question i should probably know the answer to, but.....


we have had ceiling insulation installed in our house, now they put that loose celulose stuff in the roof, and have covered up all the cables, i know as a electrician, that you shouldnt install cables in insulation without first derating the cable, and all that jazz,

so by law, should of these guy's removed all cables from the ceiling and installed the insulation under the cables? or am i trippin?

[Not_An_Abba_Fan]

Have a look around this site. Electrical safety and ceiling insulation

As far as I can tell, it is only lights that have to have clearance, not wiring.

[Troy711]

Every single job I have ever seen (that's many many hundred over the years) has had insulation installed over, under and around all electical cables and most of them don't even have cut outs for light fittings. That's not to say it is to standard... just that I've never seen it to the way you have discribed.

[edals]

Well the Dumbasses that installed mine were hopeless. They Broke my Roof hole cover, they push a down light out, and they did not cut a hole for the exhaust fan in the bathroom. All simple fixes i noticed just after they left. I got the foil type, least i know it wont catch fire! Still for free cannot complain about it.
got to watch all of them.

[Morton]

I used to install insulation, and we were only required to cut insulation around light fittings. Where I could, I used to stuff insulation UNDER loose wiring, but if the wiring was clamped or tied down to the celing beams, I just paved over it.

[mking]

whenever cables are ran through insulation they are supposed to be upsized but i dont think anyone follows this rule lol

[one_and_only2004]

they're not supposed to be upsized, just derated to something lower.

Never in my life have i seen this happen though.

[JBDrifter]

whenever cables are ran through insulation they are supposed to be upsized but i dont think anyone follows this rule lol

That depends on the electrical installation. When deciding on cable selection, insulation is just one of a number of factors that have to be considered. When running cables surrounded by insulation, you have to apply the derating factor. In most situations you would find that standard sized cables (1.5mm for lighting, 2.5mm for power etc.) will still be fine to use, unless the length of the run of cable is rather long.

Garth, it's not your problem to worry about. I know you're a sparky, as am I, but the only time you need to worry about the cable size/type, and where it's installed, is when you are installing it. If you are really that concerned about it though (I'm assuming this is in your own house?) just get out your AS3008 and work out the correct cable size using the appropraite derating factor. I'm pretty sure you'll find it'll all be ok. Might be iffy if 1mm cable was used for your lighting circuits though, but even then I'd think you'll still be alright.

[50LTRv8]

A mates house just burnt down because a downlight ignited the newly installed insulation.

[minux]

garth, you may want to read this article.

Roof insulation turns houses 'live' | The Australian

[cracker]

it will be fine, not going to make much difference really.

[Majestic 36]

garth, you may want to read this article.

Roof insulation turns houses 'live' | The Australian

I seen that on the news, would be dangerous if u went up in the roof to see the job and next thing u know.

[Garth]

they have banned the use of the alfoil stuff now finaly in all homes, they did a investigation into some of the houses done and out of the houses done, they did 10%, 2% of those houses (aprox 750) were found to have live insulation in the ceilings.



i know our rules state you cant run cables direct ontop of inside insulation without first de-rating the cable and breaker, was just curious if this should be taken into account with houses that have now had insulation installed.

[Troy711]

garth, you may want to read this article.

Roof insulation turns houses 'live' | The Australian

That hardly surprises me.. the intelligence of most installers I know is pretty low. Factor in their few breaky bongs and it makes for a serious work place safety issue.

[Troy711]

LOL

"The program to insulate 2.7 million homes has been dogged by allegations of rorting and malpractice and has led to house fires."

That also doesn't surprise me. My Dad called a contractor he has know for years and got a quote to do my sisters house and to fit R4 batts it came in at almost 300 bucks less then what the contractor who did the job quoted and he only quoted for R3.5s.