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#185652 - 03/23/09 10:38 AM Plaster Rings On Ceiling Boxes For Luimaires  
KJay  Offline
Member
Joined: Nov 2007
Posts: 763
MA, USA
In the past, I have used round metal and nonmetallic plaster rings on 4-square and nail-on ceiling boxes respectively for supporting light fixtures before the 2008 NEC without issue, but I am no longer sure if this is an approved use for these plaster rings.
Are they now relegated to use for wall mount fixtures and utilization equipment under 6-pounds?
Do these meet the requirements of 314.27[A] when used with new work ceiling boxes?
I can't seem to find any direct reference in the NEC regarding the use of these with a ceiling box when used for lumunaire support.
The UL white book only seems to mention box extensions and device boxes with plaster rings similar to the exception to 314.27[A], but nothing about plaster rings used with ceiling boxes for luminarie support. The rings themselves don't have much info on them either other than Cu. In. and UL listing.

314.20 passively mentions setback of plaster rings in walls and ceilings, but that is all.

314.27[E] refers back to 314.27[A] and the exception to 314.27[E] simply mentions plaster rings only on boxes used for support on Utilization Equipment under 6-pounds, which as I understand refers to things like smoke detectors, occupancy sensors, etc.

TKX


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#185653 - 03/23/09 11:57 AM Re: Plaster Rings On Ceiling Boxes For Luimaires [Re: KJay]  
renosteinke  Offline
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Joined: Jan 2005
Posts: 5,316
Blue Collar Country
I think that you've mixed up a few things.

Of course, that's no surprise; the NEC does not directly address the issue, despite there being some imcomplete references. The UL "White Book" does a better job.

Any securely attached metal box with a metal plaster ring - of any style - is good for supporting fixtures to 50 pounds.

The 6 pound limit you refer to is for 'old work' boxes, where the box is supported by the drywall, rather than by being attached to a framing member.


#185656 - 03/23/09 01:33 PM Re: Plaster Rings On Ceiling Boxes For Luimaires [Re: renosteinke]  
KJay  Offline
Member
Joined: Nov 2007
Posts: 763
MA, USA
Originally Posted by renosteinke
I think that you've mixed up a few things.

Of course, that's no surprise; the NEC does not directly address the issue, despite there being some imcomplete references. The UL "White Book" does a better job.

Any securely attached metal box with a metal plaster ring - of any style - is good for supporting fixtures to 50 pounds.

The 6 pound limit you refer to is for 'old work' boxes, where the box is supported by the drywall, rather than by being attached to a framing member.


Reno,
That's what I was hoping to here, but would really like to have something in writing just in case it ever comes up as an issue on a job.

I have searched the 2008 UL White Book up and down and can only find the following statements posted below regarding this.

I suppose it could be argued that since The UL White Book only references device boxes and device plaster rings, not ceiling boxes and round plaster rings, then by default they are allowed to be used in ceiling applications for fixture support.
It just seems that there should be some entry that directly addresses this to prevent any possible misinterpretation of the matter.


Metallic Outlet Boxes (QCIT)

FIXTURE SUPPORT
A box, with or without a bracket or bar hanger, intended for support of a fixture weighing 50 lbs or less is marked "FOR FIXTURE SUPPORT" on the carton to indicate that the box is intended for fixture support. A box, with or without a bracket or bar hanger, intended for support of a fixture weighing more than 50 lbs is marked with the weight of the fixture to be supported.

Metallic device boxes and device plaster rings have not been investigated for support of a ceiling fixture unless marked for use in ceilings, walls, and with the weight of the product to be supported. Metallic device boxes or metallic device boxes intended to be installed in an existing structure have been investigated for the support of fixtures, smoke detectors and carbon monoxide detectors weighing not more than 6 lbs.


Nonmetallic Outlet Boxes (QCMZ)

FIXTURE SUPPORT
A nonmetallic box, with or without a bracket or bar hanger, intended for support of a fixture weighing 50 lbs or less is marked "FOR FIXTURE SUPPORT" on the carton. A nonmetallic box, with or without a bracket or bar hanger, intended for support of a fixture weighing more than 50 lbs. is marked with the weight of the fixture to be supported.

Nonmetallic boxes and device plaster rings have not been investigated for support of a
ceiling fixture unless marked for use in ceilings, walls, and with the weight of the product to be supported. Nonmetallic device boxes or nonmetallic device boxes intended to be installed in an existing structure have been investigated for the support of fixtures, smoke detectors and carbon monoxide detectors weighing not more than 6 lbs.

TKX


#185658 - 03/23/09 03:59 PM Re: Plaster Rings On Ceiling Boxes For Luimaires [Re: KJay]  
KJay  Offline
Member
Joined: Nov 2007
Posts: 763
MA, USA
I feel much better about things now. I was able to find the specs on the Hubbell/Raco site for the 4-square 767 plaster rings that I use. They are indeed rated for 50 Lbs fixture support.

No such info available on the Allied website regarding their round 9348 nonmetallic plaster rings though, so will send an email to their tech support.


#185663 - 03/23/09 07:03 PM Re: Plaster Rings On Ceiling Boxes For Luimaires [Re: KJay]  
mikesh  Offline
Member
Joined: Jun 2006
Posts: 613
Victoria, BC, Canada
Another clue too. No box or ring that is tapped with 6/32" threaded holes is approved for fixtures. There are exceptions for some wall sconces but fixture boxes have 8/32" screw holes. 6/32" screws are for devices.



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