Long Simmering Box Fill Question - Opinions wanted?

[busman]

Situation: Metal pancake fan box is 6 cubic inches.

Code (1999):

370-16 "Boxes and conduit bodies shall be of sufficient size to provide free space for all enclosed conductors."

410-10 "Canopies and outlet boxes taken together shall provide adequate space so that fixture conductors and their connecting devices can be properly installed."

Question 1: Does this mean that box fill does not need to be calculated for a light with a large canopy OR is the pancake only good for 3 #14 wires?

Question 2: Is a paddle fan considered a light fixture for the purposes of article 410 if it does not have a light kit?

Thanks,

Mark

 

[bphgravity]

Re: Long Simmering Box Fill Question - Opinions wanted?

In my opinion, you must first consider the outlet box independent to what might be installed on it. Considering that, box fill rules will apply for the pan itself.

 

[infinity]

Re: Long Simmering Box Fill Question - Opinions wanted?

Question #1: I would say yes. In the 1999 NEC this exception to 370-16(b)(1) stated:

"Exception: An equipment grounding conductor or conductors or not over four fixture wires smaller than No. 14, or both, shall be permitted to be omitted from the calculations where they enter a box of a domed fixture or similar canopy and terminate within that box".

Question #2: I would say no. A ceiling fan is not a light fixture but the exception in question #1 would apply.


Regarding question #1, I believe the exception was added somewhere around the 1996 code cycle because there was a large number of pancake boxes being manufactured and sold although they may have been technically illegal to use because of their small volume. This gave us the exception to allow them to be used.

[ August 07, 2005, 07:54 AM: Message edited by: infinity ]

 

[busman]

Re: Long Simmering Box Fill Question - Opinions wanted?

I was thinking that a 6 cu. in. pancake box would be legal with 3 - #14 conductors and not really anything else. Seeing the exception, I guess it could be 3 #14 current carrying and an EGC.

 

[infinity]

Re: Long Simmering Box Fill Question - Opinions wanted?

Busman, that's the way I'm reading it too. This exception is in the 2005 NEC also.

 

[busman]

Re: Long Simmering Box Fill Question - Opinions wanted?

I guess I am still wondering what the language in 410-10 means.

Thanks for the responses.

Mark

 

[George Stolz]

Re: Long Simmering Box Fill Question - Opinions wanted?

I just realized that this was a 1999 NEC question exclusively, of which I don't have a copy. But I am still posting it for argument's sake.

Originally posted by busman:
I was thinking that a 6 cu. in. pancake box would be legal with 3 - #14 conductors and not really anything else. Seeing the exception, I guess it could be 3 #14 current carrying and an EGC.

I use Allied fiberglass pancake boxes marked "3.5 cu. in." Without 410.10 they'd be totally illegal - I wouldn't be able to install a single 14-2 in them.

Trevor wrote:
Question #2: I would say no. A ceiling fan is not a light fixture but the exception in question #1 would apply.

Have you seen a ceiling fan without a provision in the canopy for a light kit?

As far as the ceiling fan being a light fixture for the intentions of 314.16 and 410.10, I would say definutely, yes. The box the "thing" in question is attached to is a lighting outlet, whether the "thing" installed casts light or not.

[ August 07, 2005, 11:04 AM: Message edited by: georgestolz ]

 

[busman]

Re: Long Simmering Box Fill Question - Opinions wanted?

George,

I mentioned the question about lighting fixtures because that is the first words in the title of article 410 "Lighting Fixtures, Lampholders, Lamps, and Receptacles". Probably should use luminaire.

I started thinking about this because I have a job to install a ceiling fan in a business with a drop ceiling with wooden framing about 2 feet above the ceiling. I began with the best solution being a 2x8 attached to the framing with a fan box at the bottom. I went looking for a saddle type fan box (it has to be metal since the existing method is MC cable). The only metal box I could find with a suitable bracket (one that would attach to the bottom of the 2x8 was a pancake box. Hence the question. Any better ideas? I do much more residential than commercial so I don't do many drop ceilings.

Thanks,

Mark

 

[curt swartz]

Re: Long Simmering Box Fill Question - Opinions wanted?

George, I don?t see how 410.10 would make your installation ?legal?. 314.16 would require a box for a single 14-2 to have the volume of at least 6 cu in.

 

[LarryFine]

Re: Long Simmering Box Fill Question - Opinions wanted?

Mark, you can buy "saddle-mount" fan boxes in both plastic and metal that straddle a 2x, and have plenty of capacity.

See: http://www.aifittings.com/arliprod_n.htm

 

[George Stolz]

Re: Long Simmering Box Fill Question - Opinions wanted?

Originally posted by curt swartz:
George, I don?t see how 410.10 would make your installation ?legal?. 314.16 would require a box for a single 14-2 to have the volume of at least 6 cu in.

410.10 Space for Conductors. Canopies and outlet boxes taken together shall provide adequate space so that luminaire (fixture) conductors and their connecting devices can be properly installed.

Because 410.10 requires us to consider the space the canopy provides in our box-fill calculation.

 

[busman]

Re: Long Simmering Box Fill Question - Opinions wanted?

Larry,

A metal saddle box with 11.25 cu. in. is what I could really use. I did not see construction material on most of the boxes on the web site you showed - I could not tell if they were plastic or metal. Any chance you could give me a model number. Really appreciate it.

Mark

 

[curt swartz]

Re: Long Simmering Box Fill Question - Opinions wanted?

George, I have never seen a fixture canopy with a marked volume. Your box an canopy must comply with 314.16(A)

314.16 Number of Conductors in Outlet, Device, and Junction Boxes, and Conduit Bodies
Boxes and conduit bodies shall be of sufficient size to provide free space for all enclosed conductors. In no case shall the volume of the box, as calculated in 314.16(A), be less than the fill calculation as calculated in 314.16(B). The minimum volume for conduit bodies shall be as calculated in 314.16(C).
The provisions of this section shall not apply to terminal housings supplied with motors.

(A) Box Volume Calculations The volume of a wiring enclosure (box) shall be the total volume of the assembled sections and, where used, the space provided by plaster rings, domed covers, extension rings, and so forth, that are marked with their volume or are made from boxes the dimensions of which are listed in Table 314.16(A).

 

[busman]

Re: Long Simmering Box Fill Question - Opinions wanted?

Curt,

The only differing opinion I might have (and I subtly) highlighted it in my original post is the word "enclosed conductors". I cannot decide if the conductors are part in the box and part in the canopy if they are enclosed in the box. I think it could go either way - hence my confusion about 410-10.

Best regards,

Mark

 

[LarryFine]

Re: Long Simmering Box Fill Question - Opinions wanted?

Originally posted by busman:
Larry,

A metal saddle box with 11.25 cu. in. is what I could really use. I did not see construction material on most of the boxes on the web site you showed - I could not tell if they were plastic or metal. Any chance you could give me a model number. Really appreciate it.

Mark

Mark, the boxes here are steel, and even the shallower one is 14.6 cu.in.
http://www.aifittings.com/n_2a.htm

The third and fourth here are plastic saddles, and large enough.
http://www.aifittings.com/n_1.htm

The chart here shows the capacities of them all.
http://www.aifittings.com/n_13.htm

[ August 07, 2005, 05:07 PM: Message edited by: LarryFine ]

 

[George Stolz]

Re: Long Simmering Box Fill Question - Opinions wanted?

Originally posted by curt swartz:
George, I have never seen a fixture canopy with a marked volume. Your box an canopy must comply with 314.16(A)

So, if there is a dispute regarding the volume of an outlet box with a canopy, then follow the following process:
</font>

• <font size="2" face="Verdana, Helvetica, sans-serif">Tape the hole shut on the bottom of the canopy.</font>
• <font size="2" face="Verdana, Helvetica, sans-serif">Fill the canopy with water.</font>
• <font size="2" face="Verdana, Helvetica, sans-serif">Once full, pour the contents of the canopy into a measuring device of your choice.</font>
• <font size="2" face="Verdana, Helvetica, sans-serif">Calculate and write the volume onto the inside wall of the canopy, to mark the volume.</font>

<font size="2" face="Verdana, Helvetica, sans-serif">
But 410.10 includes the canopy in the space available for wiring.

 

[curt swartz]

Re: Long Simmering Box Fill Question - Opinions wanted?

George, I?m not saying that the canopy can?t be included but it must be marked with its volume by the manufacture. 410.10 doesn?t say you don?t have to comply with 314.16. Do you feel there is no limit to the number of conductors allowed in a box as long as a fixture (luminaire) is mounted on it?

Most electrical inspectors in my area will not accept 3/0 pancakes since the marked volume is not enough for even a single 14-2 NM cable.

[ August 07, 2005, 08:16 PM: Message edited by: curt swartz ]

 

[jwelectric]

Re: Long Simmering Box Fill Question - Opinions wanted?

Is the canopy present during the rough stage?

If not then this box is in violation of the box fill calculation outlined in 314.16 of the NEC during the time before the canopy would be installed.

It would never make it past the rough-in.

 

[busman]

Re: Long Simmering Box Fill Question - Opinions wanted?

I like the logic of jwelectric. It still leaves my original question of what does 410.10 mean?

Also, could still use some good ideas for supporting a fan box from wooden framing. The metal boxes (links provided earlier) do not have a saddle bracket and I am reluctant to use screws set in the end-grain of a piece of 2-by lumber to support a fan (algthough this may be the best I can do). All good ideas still appreciated.

Thanks to all for the lively discussion. At least there is a reason this has been troubling the back of my mind for so long.

Mark

 

[electricmanscott]

Re: Long Simmering Box Fill Question - Opinions wanted?

Originally posted by jwelectric:
Is the canopy present during the rough stage?

If not then this box is in violation of the box fill calculation outlined in 314.16 of the NEC during the time before the canopy would be installed.

It would never make it past the rough-in.

I don't believe the code applies only to certain stages of the wiring process. With your logic the job would not pass anyway because all of the boxes are not covered. I don't see why the wording to allow the fixture canopy to count in box fill calcs is even there if you are not allowed to use it.

[ August 07, 2005, 09:26 PM: Message edited by: electricmanscott ]