410.16 - Means of Support

[LarryFine]

Re: 410.16 - Means of Support

Recent experience, as opposed to opinion: We just finished a warehouse conversion, making rooms, where we coincidently installed the ceiling also.

We added no extra wires to either the troffers or grid, and the troffers are secured using only the bend-out tabs. I double-check each one.

You can not raise a troffer without damaging the grid. There was absolutely no issue with either the building or electrical inspections.

Just for info's sake, the main runners are supported every 4 feet and the ends (with the tabs), not sides, of the troffers are on the main runners.

 

[iwire]

Re: 410.16 - Means of Support

Originally posted by LarryFine:
We added no extra wires to either the troffers or grid, and the troffers are secured using only the bend-out tabs. I double-check each one.

You can not raise a troffer without damaging the grid. There was absolutely no issue with either the building or electrical inspections.

All that means is your inspector did not enforce the intent of the CMPs and that you left a violation behind.

 

[LarryFine]

Re: 410.16 - Means of Support

Originally posted by iwire:
All that means is your inspector did not enforce the intent of the CMPs...

I guess they missed the "Intentions" chapter of the NEC.

... and that you left a violation behind.

If the built-in clips are used as per the manufacturer's instructions, and obviously are meant to be used with the fixture, what is the violation? Do they not qualify as "mechanical means"?

 

[iwire]

Re: 410.16 - Means of Support

Originally posted by LarryFine:

Originally posted by iwire:
All that means is your inspector did not enforce the intent of the CMPs...

I guess they missed the "Intentions" chapter of the NEC.

... and that you left a violation behind.

If the built-in clips are used as per the manufacturer's instructions, and obviously are meant to be used with the fixture, what is the violation? Do they not qualify as "mechanical means"?

Sorry Larry I read to fast and was wrong in my reply.

IMO what you describe meets the NEC.

 

[al hildenbrand]

Re: 410.16 - Means of Support

Originally posted by don_resqcapt19:
Does anyone have a 1984 and 1987 handbook?

Commentary to 1984 NEC 410-16:

Whether a lighting fixture is attached to an outlet box or supported independently of the outlet box, care should be taken to securely and rigidly fasten the outlet box or support the independent rod or pipe hanger (as shown in Figure 370-4).

So-called drop-in fixtures or surface mounted fixtures are to be securely fastened to the framing members of "hung" or suspended ceilings by mechanical means, such as bolts, screws, or rivets, or clips identified for use with the type of ceiling framing member(s) and fixture(s), and no other support of the fixture is necessary. However, the suspended ceiling framing members must be securely attached to each other and to the building structure and, also, additional supporting wires, rods, etc., may be necessary to provide ample support of the ceiling in areas where fixtures are installed.

Commentary to 1987 NEC 410-16:

Whether a lighting fixture is attached to an outlet box or supported independently of the outlet box, care should be taken to securely and rigidly fasten the outlet box or support the independent rod or pipe hanger (as shown in Figure 370-3).

So-called drop-in fixtures or surface mounted fixtures are required to be securely fastened to the framing members of "hung" or suspended ceilings by mechanical means, such as bolts, screws, or rivets, or clips identified for use with the type of ceiling framing member(s) and fixture(s), and no other support of the fixture is necessary. However, the suspended ceiling framing members must be securely attached to each other and to the building structure and, also, additional supporting wires, rods, etc., may be necessary to provide ample support of the ceiling in areas where fixtures are installed.

Figure 370-3 and Figure 370-4 were identical, showing a luminaire heavier than 50 pounds hanging in a masonry arch. They are the counterpart of today's Exhibit 314.8.

 

[don_resqcapt19]

Re: 410.16 - Means of Support

Thanks Al. They really didn't address the issue at that point in time.
Don

 

[sandsnow]

Re: 410.16 - Means of Support

Originally posted by LarryFine:


We added no extra wires to either the troffers or grid, and the troffers are secured using only the bend-out tabs. I double-check each one.

Larry
I would say it's quite possible you had an NEC compliant install. There's a small chance you did not. Let me explain.
Can we call the built in tabs; "clips"? That's how I see them.
We then come to the NEC req. that the clips are to be listed for the luminaire and for the grid for them to be acceptable.
I did some research on this and found that the integral tabs or clips are indeed listed for the grid type. On the luminaire carton(I can't remember the manufacturer), it has a blurb about the ceiling grid type and it gives a code letter. NEMA identifies t-bar grid by dimensions and assigns a code letter. It's been a while, but I'm pretty sure you have to use all four.
The ceiling compatibility standard is a free download after you register at the NEMA site for free. The number is LE 4-2001.
UL evaluates this by turning the grid with the luminaire upside down to see if it falls out. I spoke to UL because our building code requires to means of attachment to hold the weight of the luminaire in any direction. That's another issue.
A few people have taken advantage of this. Where the problem comes is where the luminaire bears on cross tees (smaller than the mains). The clips are not designed for those smaller tee's.
Where this is an advantage is in the parabolic or indirect type. Where if you tek screw to the grid it tweaks the luminaire.
Other people have solved this problem by using tie wire to fasten the luminaire to the grid.
Generally if you order troffers to match the grid type you'll be sittin' pretty most of the time.

 

[LarryFine]

Re: 410.16 - Means of Support

Originally posted by iwire:
Sorry Larry I read to fast and was wrong in my reply.

IMO what you describe meets the NEC.

No apology necessary. I was definitely not as serious in my reply as it may have seemed. We're cool!

Originally posted by sandsnow:
It's been a while, but I'm pretty sure you have to use all four.

I did.

Where the problem comes is where the luminaire bears on cross tees (smaller than the mains). The clips are not designed for those smaller tee's.

No, I intentionally ran the main runners perpendicular to the 2x4 fixtures and 2x4 tiles, using only 4' cross T's. The clpips all attach to main runners only.

 

[George Stolz]

Re: 410.16 - Means of Support

Originally posted by charlie b:
There is a great tendency for anyone who is convinced of the correctness of his or her interpretation to be equally convinced that no other interpretation can be reasonably supported.

Well put.

 

[George Stolz]

Re: 410.16 - Means of Support

Personally, I'd just shove the first sentence to the end of the paragraph, and substantiate it with Don's old ROP's.

But I'm lazy.

(C) Suspended Ceilings. Luminaires (fixtures) shall be securely fastened to the ceiling framing grid by mechanical means such as bolts, screws, or rivets. Listed clips identified for use with the type of ceiling framing member(s) and luminaire(s) shall also be permitted. Framing members of suspended ceiling systems used to support luminaires (fixtures) shall be securely fastened to each other and shall be securely attached to the building structure at appropriate intervals.

[ January 06, 2006, 08:16 AM: Message edited by: georgestolz ]

 

[charlie b]

Re: 410.16 - Means of Support

Originally posted by georgestolz: You have an extra word in there:

410.16(C) Suspended Ceilings. Framing members of suspended ceiling systems used to support luminaires (fixtures) shall be securely fastened to each other and shall be securely attached to the building structure at appropriate intervals. Regardless of the method of provide support for the weight of a luminaire, it shall be securely fastened to the ceiling framing member by mechanical means such as bolts, screws, or rivets. Listed clips identified for use with the type of ceiling framing member(s) and luminaire(s) shall also be permitted.

I saw that error too late. I had intended to say "providing." I've already fixed it in my "2011 changes" file.

 

[sandsnow]

Re: 410.16 - Means of Support

Originally posted by LarryFine:
No, I intentionally ran the main runners perpendicular to the 2x4 fixtures and 2x4 tiles, using only 4' cross T's. The clpips all attach to main runners only.

Right, I saw that in your post. I was trying to make my post apply as an FYI to anyone as well as address your install.