410.16 - Means of Support

iwire · Dec 31, 2005

Re: 410.16 - Means of Support

Originally posted by j_erickson:
Fortunately again, I'm in MA so it's not an issue for me.

apauling · Dec 31, 2005

Re: 410.16 - Means of Support

okay bob, no sheetrock screws

Fred S. · Dec 31, 2005

Re: 410.16 - Means of Support

Just because someone "wasted ink" writing something out of the NEC doesn't mean you don't have to follow the structual code IBC etc. Also, just because the NEC regurgitated only a parcial code from the IBC for your reference doesn't mean you only have to follow that half. ( for those of you that think it doesn't say what it does )

iwire · Dec 31, 2005

Re: 410.16 - Means of Support

Originally posted by Fred S.:
Just because someone "wasted ink" writing something out of the NEC doesn't mean you don't have to follow the structural code IBC etc.

Fred, in MA we do not have to secure drop in fixtures to the grid.

We do not use the IBC and apparently the MA building code does not require securing the fixtures to the grid either.

Each area has different rules no matter how "National" or "International" a code tries to be.

paul · Dec 31, 2005

Re: 410.16 - Means of Support

Here, if you want the job passed off, it's a wire in opposite corners and clips or screws for troffers.

steve66 · Jan 3, 2006

Re: 410.16 - Means of Support

Posted by Paul:

All i want to point out is that 2 wires do not adequately support an electrical fixture, it will flop all over the place without the grid.

It's a light fixture, not a largemouth bass

Two wires, and it won't fall on anyone's head.

But I can't argue with Don's research. Apparently, the NEC does want the fixture fastened to the grid.

Steve

charlie b · Jan 3, 2006

Re: 410.16 - Means of Support

Originally posted by iwire: And I still do not agree that the first sentence has any influence on the second sentence.

I doubt that you and I will agree on this one Bob (or Don). But let me try one more time. Even if you don't agree with it, perhaps you might concede that this point of view has merit. Here's a "thought experiment":

Delete the first sentence of 410.16(C).

Read the second. It says to fasten the fixture to the grid.

What grid? There is no discussion of a grid, and there are no requirements concerning the means of installing a grid (remember, the first sentence is not there).

So I can build a flimsy grid (nothing tells me I can't), and firmly attach the fixture to it.

The next day, the grid falls apart, and the fixture dangles by its cord.

Inference: The fact that you are required to firmly attach the fixture to the grid (i.e., sentence two) presumes that the grid is sturdy enough to hold it (i.e., sentence one).

Inference: That means that you must follow the rules in sentence 1 (i.e., interlock the grid members to each other, and attach the grid firmly to the building).

Conclusion: The second sentence has no validity, without the existence of the first.

Observation: The first sentence clearly states that it applies only if it is your intent to support the fixture from the grid. (Please tell me you see that, and agree with that!).

Inference: If you don't intend to support the fixture from the grid, then the first sentence does not apply.

Conclusion: If you don't intend to support the fixture from the grid, then the second sentence does not apply, and you don't have to attach the fixture to the grid.

apauling · Jan 3, 2006

Re: 410.16 - Means of Support

if anyone thinks 2 wires is adequate support for a troffer, try that as the lone support in an area where the troffers have no grid or other support. the inspector would have to be the contractor's brother to pass it.

paul

don_resqcapt19 · Jan 3, 2006

Re: 410.16 - Means of Support

Charlie,
First you are correct. I still don?t agree.

Delete the first sentence of 410.16(C).
Read the second. It says to fasten the fixture to the grid.
What grid? There is no discussion of a grid, and there are no requirements concerning the means of installing a grid (remember, the first sentence is not there).

The title of the section is ?suspended ceilings?. That implies a gird of some type.

So I can build a flimsy grid (nothing tells me I can't), and firmly attach the fixture to it.

410.15(A) requires that the fixture to be securely supported. A ?flimsy grid? will not provide the required support.

The next day, the grid falls apart, and the fixture dangles by its cord.
Inference: The fact that you are required to firmly attach the fixture to the grid (i.e., sentence two) presumes that the grid is sturdy enough to hold it (i.e., sentence one).

No. Sentence one only tells us how the grid must be installed when it is used to support the fixture.

Inference: That means that you must follow the rules in sentence 1 (i.e., interlock the grid members to each other, and attach the grid firmly to the building).

True.

Conclusion: The second sentence has no validity, without the existence of the first.

No. The CMP in its wisdom, has said that the fixture must be secured to the gird in all cases, not just when the grid provides the required fixture support. There is no wording in the section that ties the second sentence to the first one. That wording was removed in the 87 edition of the code. Prior to that time, the code clearly tied the two sentences together.

Observation: The first sentence clearly states that it applies only if it is your intent to support the fixture from the grid. (Please tell me you see that, and agree with that!).

Yes, that is correct.

Inference: If you don't intend to support the fixture from the grid, then the first sentence does not apply.

Correct.

Conclusion: If you don't intend to support the fixture from the grid, then the second sentence does not apply, and you don't have to attach the fixture to the grid.

Incorrect. There is nothing in the code that says the you only apply the second rule when the grid is providing the fixture support.

Don

LarryFine · Jan 3, 2006

Re: 410.16 - Means of Support

Originally posted by don_resqcapt19:
There is nothing in the code that says the you only apply the second rule when the grid is providing the fixture support.

Yes, there is, and you mentioned it yourself:

Originally posted by don_resqcapt19:
Sentence one only tells us how the grid must be installed when it is used to support the fixture.

This implies that it is possible for the grid to not be providing the support. Would we want the fixture to provide support for the grid?

If the grid is not supporting the fixture, why must the fixture be attached to it, beyond gravity?

don_resqcapt19 · Jan 4, 2006

Re: 410.16 - Means of Support

Larry,

If the grid is not supporting the fixture, why must the fixture be attached to it, beyond gravity?

Because the code says so, and has said this since the change that was made in the 1987 code. Where is the word that says, you only secure the fixture to the grid if the grid is supporting the fixture. The two ideas in that code section are stand alone and independent.
Don

[ January 04, 2006, 07:20 AM: Message edited by: don_resqcapt19 ]

JohnE · Jan 4, 2006

Re: 410.16 - Means of Support

Don,

Respectfully, the way I read and interpret 410.16(c), it is only discussing fixtures which are supported by a suspended ceiling. I understand that your research of cmp comments indicate otherwise, but as it is worded now, I feel that if a fixture is supported adequately and independently of the suspended ceiling, then 410.16(C) does not apply.

If, say, a fluorescent wrap fixture were installed under a suspended ceiling and were hung from threaded rod to the structural ceiling above the grid, do you feel that is also required to be fastened to the grid?

iwire · Jan 4, 2006

Re: 410.16 - Means of Support

I respectfully can not fathom how it can be interpreted any other way than Don's way.

But now we also know what the CMP intended and we are still batting this around.

Kinda crazy.

[ January 04, 2006, 08:35 AM: Message edited by: iwire ]

JohnE · Jan 4, 2006

Re: 410.16 - Means of Support

Originally posted by iwire:
I respectfully can not fathom how it can be interpreted any other way than Don's way. As someone else mentioned, it is still just someone's opinion. Apparantly, though, their opinion is valued enough for a large number of people to purchase their product.

Since we know CMP intent, why don't they just clarify their wording? I guess then we'd have no fun.

iwire · Jan 4, 2006

Re: 410.16 - Means of Support

Originally posted by j_erickson:
why don't they just clarify their wording? I guess then we'd have no fun.

Good point.

don_resqcapt19 · Jan 4, 2006

Re: 410.16 - Means of Support

The guys writing the handbook interpret it other than Don's way.

Does anyone have a 1984 and 1987 handbook? If so, was there any change in the commentary wording? It is my guess that they missed the change in the 87 code and since there have been no changes in this section after that, they have not reviewed the commentary wording. I would expect that they only revise the commentary for the sections that have changes and do not review the complete handbook every three years.
I have an e-mail into the editor of the handbook asking about this issue. Not sure if I will get a response.
Don

corrected typos

[ January 04, 2006, 11:16 AM: Message edited by: don_resqcapt19 ]

charlie b · Jan 4, 2006

Re: 410.16 - Means of Support

Perhaps we can all agree on this statement:

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.

I believe that this is a key reason that politics and religion are such difficult topics for people of opposing beliefs to discuss in a rational, civil, and respectful manner.

So we will leave this discussion without resolution. I think the wording does not reflect the intention of its authors. Don and Bob think it does. So be it.

I have started a file that I will save on my computer, with naive confidence that I will remember it is there in 2.5 years. I have called it "Proposed Changes for 2011 NEC." The first item on that list is the proposal that the text shown below in bold be added to the article under discussion.

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.

iwire · Jan 4, 2006

Re: 410.16 - Means of Support

Originally posted by charlie b:
Perhaps we can all agree on this statement:

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.

Click to expand...

Yes, I can definitely agree to that.

Still waiting for Pierre's wife to weigh in on this.

(A person who will likely have no bias)

sandsnow · Jan 4, 2006

Re: 410.16 - Means of Support

Originally posted by charlie b:
[QB] Perhaps we can all agree on this statement:

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.

Click to expand...

I like this as I like Charlie's Rule of Technical Reading. Will this become Charlie's Rule #2??

Charlie, have you quoted this before?? It's validity is proved here on almost a daily basis!!

I'd like to use this in my classes. Who would I quote or credit?

BTW. My two cents on the issue at hand. The code as written does not require fastening to grid if luminaires are supported independently. The wires would have to be taut, both run up at the same angle and etc. Local building code left out of the discussion.

The reality of this is it's not going to happen. I don't believe contractors will want their men to take the extra time to do it just to save putting in two tek screws. Also if you try to present your case to some inspectors, you'll run into conflict because of the rule above.

charlie b · Jan 4, 2006

Re: 410.16 - Means of Support

Thanks, Larry. Yes it is another of my creations. And you are welcome to use it anytime.

410.16 - Means of Support

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