rectangular boxes for ceiling fixture?


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Old 10-22-11, 09:04 AM
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rectangular boxes for ceiling fixture?

I'm putting in two mini-pendants above a peninsula and the center line is right on the outside edge of a ceiling joist. I've got two switches on opposite sides of the room, so I'm using 14/3 and have cable needing to both enter and exit the box. This is too much for a pancake box, but the circular old work ceiling boxes are set too far off center.

If I used a rectangular box for a wall receptacle, it could sit right alongside the joist and not be far enough off of my mark to be noticeably off center. The mounting bracket for the fixture seems to fit. Is there any reason why I can't use a rectangular box meant for a wall receptacle in the ceiling instead?
 
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Old 10-22-11, 01:46 PM
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You can use a fan box as per this link that will span over your ceiling joist. They also make one that is 1/2 offset of the joist....your choice.
Pass & Seymour Ceiling Fan Box - Nextag Stores
 
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Old 10-22-11, 02:57 PM
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Thanks, chandler!

If I remember correctly, there's some blocking on the other side of that joist to help anchor a drywall patch in that area, so that box pictured in the link won't work. I can't find the offset one you mentioned, but that sounds like it could work.

If I don't find the offset, could I use a single gang rectangular old work box? Is there a code specifying that ceiling fixture boxes need to be round?
 
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Old 10-22-11, 03:04 PM
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Is it this one, chandler:

http://www.menards.com/main/electrical/rough-electrical/junction-boxes/pvc/slater-reg-ceiling-box-direct-mount-9-0-cu-in/p-1403195.htm

If so, it still doesn't meet the box fill requirement for two 14/3 cables.
 
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Old 10-22-11, 03:20 PM
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Big orange sells the boxes, but I just can't find a picture for you. It is similar to the one pictured in the link, but the offset is on one side and only 1/2 the box sticks up alongside the joist. I believe it will work for you. a rectangular box won't give you a proper span for the yoke, and an old work box may not take the pressure of the pendants (no weight mentioned).

There ya go! I am sure it will have space for 2 ea 14-2. Will it fit the application with your space requirements? It has as much space, plus some as does a pancake box.
 
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Old 10-23-11, 06:34 AM
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I believe for 2 cables of 14/3 I need 14 cu, and the link I sent for the offset box only has 9. I'll have a look at big orange later today and see if the one they sell is larger.

I don't know the weight of the pendants, but they are simple mini-pendants, so not that heavy. The mounting bracket does seem to fit the span of the screw holes in the rectangular box.

Which would be the lesser evil--exceeding box fill with the offset joist box that's round, or using a rectangular box instead of a round one? My guess is that exceeding box fill by using the offset box is worse. As long as the mounting bracket fits and the pendant isn't heavy, is there a code related to round boxes for ceiling fixtures?

Thanks for all the help!
 
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Old 10-23-11, 06:56 AM
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I believe for 2 cables of 14/3 I need 14 cu, and the link I sent for the offset box only has 9.
Why not use 14-2, then you wouldn't have capacity problems.

I don't know the weight of the pendants, but they are simple mini-pendants, so not that heavy. The mounting bracket does seem to fit the span of the screw holes in the rectangular box.
I would never trust an old work box which is retained by the edges of the drywall to hang a fixture regardless of weight.
 
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Old 10-23-11, 07:01 AM
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Thanks, CasualJoe.

I'm using 14/3 because I have a switch on both ends of the room to control the pendants.
 
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Old 10-23-11, 08:08 AM
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Here is the latest code requirement for ceiling boxes.

314.27 Outlet Boxes.
(A) Boxes at Luminaire or Lampholder Outlets. Outlet
boxes or fittings designed for the support of luminaires and
lampholders, and installed as required by 314.23, shall be
permitted to support a luminaire or lampholder.
(1) Wall Outlets. Boxes used at luminaire 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).
Exception: A wall-mounted luminaire or lampholder weighing
not more than 3 kg (6 lb) shall be permitted to be supported
on other boxes or plaster rings that are secured to
other boxes, provided the luminaire or its supporting yoke, or
the lampholder, is secured to the box with no fewer than two
No. 6 or larger screws.
(2) Ceiling Outlets. At every outlet used exclusively for
lighting, the box shall be designed or installed so that a
luminaire or lampholder may be attached. Boxes shall be required to support a luminaire weighing a minimum of 23
kg (50 lb). A luminaire that weighs more than 23 kg (50 lb)
shall be supported independently of the outlet box, unless
the outlet box is listed and marked for the maximum weight
to be supported.

Rectangular device boxes use 6-32 screws and cannot be used for ceiling mounted fixtures.
 
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Old 10-23-11, 09:11 AM
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Originally Posted by nugentcn View Post
Thanks, CasualJoe.

I'm using 14/3 because I have a switch on both ends of the room to control the pendants.
There are multiple ways of wiring a 3-way switch circuit, using 14-3 to each ceiling fixture box is not necessary.
 
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Old 10-23-11, 05:28 PM
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I use 4x4 box on all my ceiling fixtures in my house. I just use a ceiling rounded mud ring over it.



I did it so I can buy a box of 50 4x4 metal boxes and use it for both walls and ceiling whenever. However I do secure them to the framing.
 
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Old 10-23-11, 06:11 PM
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Thanks, all. I found the offset boxes at big orange, and they are 13.4 cu. So they just barely don't work for the 14 cu requirement of 2 14/3 cables.

CasualJoe, I only know of the three-wire cable way of wiring three-way switches. Also, I'd already run the three-wire before I got to a point where I was ready to install some boxes.

So if I use an alternative method, could I cap off the red? Do capped-off wires that enter but do not leave the box count toward box fill?
 
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Old 10-23-11, 07:20 PM
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This is the one you saw, right?



You are running these 14/3 cables from scratch, right? They are not existing? If you use MC flexible conduit with individual THHN conductors instead of the Romex, and make the switch travelers pass through the box unspliced, it will count as two conductors instead of four, and you will be within the fill limit. If a wire enters a box, even if it is capped, it is counted towards fill.

Or, if there is attic access from above, you can just make the switch splices in a box mounted to the top of the joist and simply run a 14/2 pigtail into the light boxes.

Another option is to run 14/3 from one switch box to the other, bypassing the lights entirely, then run 14/2 from one switch box to the light boxes.
 
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Old 10-23-11, 11:03 PM
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Can someone please explain to me how this fellow is going to make this work. If he has one 14-3 run from the switch through his lights to his other switch, with just three wires. two for lights one for travellers
 
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Old 10-24-11, 04:59 AM
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Yep, those are the boxes I found. Thanks for all the ideas, JerseyMatt. I have small holes in the ceiling and already have the Romex in place, so THHN is out. I don't have attic access above.

Is there any wiring configuration at the lights that would allow this sequence to work?:

Switch -- 14/3 --> Light -- 14/2 --> Light -- 14/3 --> Switch

It would be easy to replace the small segment that runs between the boxes with 14/2, and this would bring the fill for each box down to 12.
 
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Old 10-24-11, 06:23 AM
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Can you run 14-3 directly between the switches? Does power come in at one of the switches?
 
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Old 10-24-11, 08:08 AM
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Power comes in at one of the switches. It would be tricky, but if I bought more 14/3 I could run another line from switch to switch.

The 14/3 I had is currently already run and cut at the holes for each ceiling box. Removing the 14/3 that is already there and replacing it with something else would be a nightmare. It was run and secured during a kitchen renovation a year ago when ceiling and walls were open. Boxes weren't installed at that time because the exact final length of the peninsula had not been decided to know the precise location of the boxes.

So let me revise my figure based on where power is. Is there any wiring configuration at the lights that would allow this sequence to work?:

Power --> Switch -- 14/3 --> Light -- 14/2 --> Light -- 14/3 --> Switch

It would be do-able to replace the small segment that runs between the boxes with 14/2, and this would bring the fill for each box down to 12.
 
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Old 10-24-11, 09:45 AM
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Correct me if I'm wrong, but it looks like the only way my diagram would work is if I had TWO 14/2 cables connecting the two lights, according to this diagram:

http://www.homeimprovementweb.com/information/how-to/three-way-switch-option7.htm

This would put me even further over the box fill than the 0.6 I am over with the one 14/3 cable.

I found these, which might be my easiest solution:

http://www.amazon.com/gp/product/B002W6ZOVA/ref=noref?ie=UTF8&s=hi&psc=1

It's too bad I'd need to pay this much for an extra 0.6 cu, but what can you do?
 
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Old 10-24-11, 12:47 PM
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Yeah that box will be your best bet, and your only shot at being able to daisy chain the boxes the way you want. Look at it this way, it's cheaper than another roll of 14/3 to go switch to switch (assuming it's more than 25 cable feet and you need the 50' roll)

And you are correct, you will need FOUR conductors between the two ceiling boxes in order to make the 3 way switch work. One pair will be carrying the travelers through, and the other will be power and neutral for the lights. Looks like except for Bobbi we all missed that one!
 
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Old 10-26-11, 12:23 PM
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Thanks for all of the help, everyone! I got lots of good ideas and learned a whole lot.
 
 

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