Support for heavy light fixtures.

[gary]

314.27(B) Maximum Luminaire (Fixture) Weight

Outlet boxes or fittings installed as required by 314.23 shall be permitted to support luminaires (lighting fixtures) weighing 23 kg (50 lb) or less. A luminaire (lighting fixture) that weighs more than 23 kg (50 lb) shall be supported independently of the outlet box unless the outlet box is listed for the weight to be supported.

Does this code reference really say that a properly installed 3 1/2 or 4" plastic nail-on box is permitted to support a 50# light fixture? Anybody know how much stress you can put on two 6-32 screws before they will fail or pull out of a plastic box? Also, wouldn't it be nice if manufacturers were required to specify the installed weight of their fixtures including bulbs, shades, and any other accoutrements?

 

[mdshunk]

Re: Support for heavy light fixtures.

According to the UL White Book, any ceiling box that is marked "For Fixture Support" is intended for hanging fixtures weighing 50 lbs or less. That amazes me too, but that's what it says. I often use extra long 8-32's for the heavy fixtures just to get the maximum number of threads engaged.

[ June 19, 2005, 02:05 PM: Message edited by: mdshunk ]

 

[iwire]

Re: Support for heavy light fixtures.

Originally posted by gary:
Does this code reference really say that a properly installed 3 1/2 or 4" plastic nail-on box is permitted to support a 50# light fixture?

Yes it does, keep in mind the code is only the minimum.

Originally posted by gary:
Anybody know how much stress you can put on two 6-32 screws before they will fail or pull out of a plastic box?

The box 314.27(B) speaks of will have 8-32 screws. Outlet boxes have 8-32 screws device boxes have 6-32 screws.

Originally posted by gary:
Also, wouldn't it be nice if manufacturers were required to specify the installed weight of their fixtures including bulbs, shades, and any other accoutrements?

Yes that is a great idea.

 

[celtic]

Re: Support for heavy light fixtures.

Originally posted by iwire:

Originally posted by gary:
Also, wouldn't it be nice if manufacturers were required to specify the installed weight of their fixtures including bulbs, shades, and any other accoutrements?

Yes that is a great idea.

With so many different shades and "accoutrements" interchangable, that probably won't happen any time soon....and if the bulb manufac. differs from the lamp manufac. - who calculates the weight?
Oh yea, me ~ the EC/EU

 

[gary]

Re: Support for heavy light fixtures.

Thanks for the replies guys, and of course you're right, iwire, about the screw size. I assume these things are lab tested to failure with a substantial safety margin before they're put on the market with a UL seal of approval.

 

[allenwayne]

Re: Support for heavy light fixtures.

Usually fixture specs are already done.Common scense does take a seat in this thread If I have a 30 ft entry fixture and a large window it`s a no brainer.affix a deep octagon and above mount a 2x8 with 1/4 in holes to match the box,run double nutted allthread through both with fender washers on top plate secure another washer & nut inside the box and extend then 2 ins past the bottom of the box.leave a nut loose inside the box to allow a clean thread when excess is cut off.This method has allowed 150 lb crystal monsters to be mounted safely.The box is just a junction the allthread is the support