Where to buy a 4 1/2" outlet box that is open on both sides for back-to-back light fixture installation?
December 12, 2010 12:46 PM   Subscribe

Where to buy a 4 1/2" outlet box that is open on both sides for back-to-back light fixture installation?

Howdy folks,

I am replacing two light fixtures that are back-to-back in adjacent rooms. There were no outlet boxes used for the old lights, but I need outlet boxes for the new lights. The problem is that if I put a conventional outlet box in one room then there's no room for the outlet box for the other room (and vice versa). Moving the holes is not really an option because they are currently both centered in the available space.

I saw referenced in one electrician's forum a 4 1/2" outlet box that was open on both the front and back exactly for this situation, but there was no link and I don't know what it's called so Google has failed me so far (or I have failed Google). Anybody know what such boxes are called, and where I can buy them online? I need an old work version, by the way.

Thank you!

posted by Jim Biancolo to Home & Garden (7 answers total)
Maybe a junction box extension/extender would work?
posted by misterbrandt at 1:04 PM on December 12, 2010

Here's a bunch of google results that may point you in the right direction.
posted by buttercup at 1:32 PM on December 12, 2010

How about two pancake boxes joined by a conduit nipple of the required length?

You would double nut the conduit nipple (nut on outside and inside of each box).
posted by davey_darling at 3:27 PM on December 12, 2010

Best answer: Is this a standard 2x4 framed, gyproc sheathed wall? Is 4 1/2" the total depth of box you require?

If the above answers are yes then I've never seen such a beast; it is sure to be a special order/internet only item if it even exists. What I would do instead is get a pair of metal swing arm, 2 1/8" deep, rework octagonal boxes with centre knockouts. Back to back they'll be 4 1/2" deep.

I'd then use a bushed nipple to join the two boxes via the centre knock outs. Voila, double depth, back to back rework box.

If you can't find 2 1/8" deep rework boxes then two 1 1/2" plus a 1 1/2" extension ring would also make up your 4 1/2". Either way you'll need to take all the ground and cable clamp screws outand then carefully line the holes up and run the clamp screws through both boxes. If you end up with a little space between the boxes don't work about it; most fixtures will hide a box that is a little proud of the surface.

Pancake boxes aren't ging to work for this because you are only allowed 3 wires in a pancake box. On one side you'll have a minimum of 4 wires (two in and two out) plus three marrettes (which counts as 1 wire). However you could use a conduit nipple with a pair of 1 1/2" boxes. It would be a bit more complicated to assemble but as a bonus you'd eliminate screw interference on the back sides of the boxes.
posted by Mitheral at 3:52 PM on December 12, 2010

Response by poster: Thanks gang! I think Mitheral's is the one I'll take to the hardware store (yes, 2x4 framed, drywall, 4 1/2" total depth of box), but this is all good stuff.
posted by Jim Biancolo at 4:09 PM on December 12, 2010

On further thought unless you have special needs of some sort there isn't any requirement to actually join the boxes together physically. You could mount your first 1 1/2" rework box and then run a short loop of loomex/NMD90 (IE: regular sheathed house wire) between the first box and the second. With 1 1/2" boxes there will be plenty of space between the boxes and when installing rework boxes the cable doesn't have to be stapled as long as it is protected from mechanical damage all around (IE: installed in a framed gyproc wall). This will work unless one of your boxes has more than 3 pieces of sheathed wire entering it (because rework octagonal boxes usually only have 4 cable clamps built in).
posted by Mitheral at 4:30 PM on December 12, 2010

Response by poster: Ah, good point, that makes sense, thank you again!
posted by Jim Biancolo at 6:41 AM on December 13, 2010

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