Nec 314.27 (a)(1)

[erickench]

Hi guys, I'm preparing a new proposal for the above NEC section. There seem's to be a problem with the language. The present 2011 NEC state's the following:

Boxes used at luminaires or lampholder outlets in a wall shall be marked on the interior of the box to indicate the maximum weight of the luminaire that is permitted to be supported by the box in the wall, if other than 23 kg (50 lb).

The problem is the word "other" used in this NEC section. "Other" implies that the permitted weight of the box could be less than or greater than 50 lbs. What I need to know is what is the present practice of the manufacturers? Do they mark the box if it can hold more than 50 lbs or less? I'm an engineer not an electrician. I nor the CMP expects the manufacturers to change their practices on account of any proposal that I make.

 

[don_resqcapt19]

The following is from the UL GuideInfo Metallic Outlet Boxes

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.

 

[erickench]

Thanks very much Don. I will attach the UL certification to the proposal.

 

[gndrod]

fan support

fan support

Hi guys, I'm preparing a new proposal for the above NEC section. There seem's to be a problem with the language. The present 2011 NEC state's the following:

Boxes used at luminaires or lampholder outlets in a wall shall be marked on the interior of the box to indicate the maximum weight of the luminaire that is permitted to be supported by the box in the wall, if other than 23 kg (50 lb).

The problem is the word "other" used in this NEC section. "Other" implies that the permitted weight of the box could be less than or greater than 50 lbs. What I need to know is what is the present practice of the manufacturers? Do they mark the box if it can hold more than 50 lbs or less? I'm an engineer not an electrician. I nor the CMP expects the manufacturers to change their practices on account of any proposal that I make.

Hi Eric,
I just now happened to have in my hands a 2 hr rated ceiling 'saddle box' by RACO and the marking in the UL Listed box reads "FOR USE IN WALLS AND CEILINGS WITH NONMETALLIC WIRING SYSTEMS, LISTED FOR FAN AND FIXTURE SUPPORT, UP TO 70 LBS."

I can see the confusion with the 50 lb. or less raceway supported luminaire box weight reference as 314.27(C) mentions outlet boxes designed to support ceiling suspended (paddle) fans that weight more than 35 lbs. have required marking to include a maximum weight to be supported. Maybe replacing "other" with 'up to' would reflect a higher open weight use from 50lbs. in the terminology presently stated. Looks like there is a lot more work here for improvement. Good luck.

 

[jimport]

I don't see the need for the change. The wording is for a default rating of up to 50 lbs that can be supported. If the box can support more it must be labeled with the higher value. Any fixture less than the 50 lb default would be fine.

 

[iwire]

I don't see the need for the change. The wording is for a default rating of up to 50 lbs that can be supported. If the box can support more it must be labeled with the higher value. Any fixture less than the 50 lb default would be fine.

I agree with you.

 

[Ponchik]

I agree with you.

I would default back to 50 lbs my self but I also agree think there should be a change:
"other than 50 lbs" to "higher than 50 lbs"