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Posted By Topic: Side Clearance on Halogen

JD
Apr 04 2013 13:07

HI,

We have the following halogens

http://www.halcyonlights.co.nz/halogen/rc362-ba

With a documents side clearance of 75MM. I just want to confirm that side clearance is measured from the edge of the CAN and not the middle of the fitting?

RC361, RC362,
CLOSED
ABUTTED
-
HC: 50mm
SC: 75mm
CA135

From what i can find its measured from the outside edge of the can or light fitting/hole edge, i just wanted to confirm.

Where you need to have a smaller gap, is there a way to heat proof the timber, eg there is only one spot for the light to go, so put some kind of insulating wrap on the timber ( might even be a heat proof gib.? )

Attached is a picture of one of my lights in which you can see the heat cans, a conduit and beam, to me this is not legit?

Your thoughts?
Thanks
   

AlecK
Apr 04 2013 13:34

From what i can find its measured from the outside edge of the can or light fitting/hole edge, i just wanted to confirm.

Yes, as shown in Fig 4.7


Where you need to have a smaller gap, is there a way to heat proof the timber, eg there is only one spot for the light to go, so put some kind of insulating wrap on the timber ( might even be a heat proof gib.? )

No, because placing something in between does not increase the distance.

That's not to say it won't in some cases be effective , but the clause is so damn long and complicated already; and adding in what would and wouldn't be considered acceptable would take an awfull lot of words.

Eg if what you cover the wood with is metal, it'll be fire resistant but will still let the heat through to the wood.
But if you space the metal off the wood, so the gap gets ventilated, maybe the wood won't get enough heat to suffer.

If you use something with thermal insulation properties, how much of each different type would be enough?

Doing the controlled experiments to determine this sort of stuff in order to have a basis for a rule would be very expensive, so the simple answer is to leave it in the too-hard basket and just set a clearance.


   

JD
Apr 04 2013 14:05

Thanks for that feedback, fully understand the complications in multiple test scenarios. Well i guess there is nothing more to do than to get the sparky to move the lights..

Cheers
   

JD
Apr 15 2013 08:34

So an update on this.

Someone has decided that rather than move the lights some hardie board nailed to the beam sitting between the light and the wood will do the job.

As a home owner this seems like the "home job" solution, not what a proper sparky/builder should be doing? any thoughts or feedback on this is appreciated.. By hardie board im talking about cement board, i think the same stuff thats used on your sofits.

Thanks.
   

AlecK
Apr 15 2013 10:29

Thee is nothing in Wiring Rules or Building code that says this sort of thing is an acceptable solution.

so while it may - or may not - be effective, it does NOT make a non-compliant installation into a compliant one.

In the absence of laboratory test results showing that x mm of a particular substance has a known thermal resistance (R value), and that that R-value will be sufficient to prevent pyrolysis at that distance from that type of heat source....this so-called "fix" is just an attempt to avoid the cost of actually complying.
But it does indicate that they recognise that they failed to comply.

Don't accept this "she'll be right" stuff, insist on full compliance. You can bet your insurers will, and if the worst happens they will be quick to use any excuse to avoid paying.
Might even be worth asking your insurers whether they ill accept it, there's a tiny chance they might but a much better chance they'll insist on the lights being moved... either way you'll want it in writing.
   

Apprentice
Apr 15 2013 17:16

An alternative solution to moving the lights could be to upgrade the fittings to a led that allows closer distances to combustible material.
   

JD
Apr 16 2013 09:15

Yes, thats what i have been researching, its still costly, with LED modules from Switch Lighting in nelson costing around 100 a light.. but that is what we may need to do to achieve a safe environment.