Home>Discussions>ELECTRICAL & LIGHTING>What Size Box for outside Wall Light Fixture???
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What Size Box for outside Wall Light Fixture???

A friend is ask me about just what size box is the right one for an outdoor Wall Light Fixture, like a "Jelly Jar" Light? Seems that the ones out there have no information as to what box the fixture fits and the stores don't like you opening the box to try and get this information. Is the Right Old Work Box the right one it seems a little large at least "Carlon" Brand is 3 3/8 yet there was another box that was about 1/4 inch smaller in diameter.

The box outside edge appears to be as large as the light and would make it not sit flush up against the flat wall surface and the box bevels down to the outside edge. Being these light are going outside would you not want it to mount flush up against the wall witha minimal amount of silicone around it to keep water out?

So what box is it and can you get it at Home Depot or Lowes or these just what the sell and need to go to a electrical supply for the right size box?


Re: What Size Box for outside Wall Light Fixture???

Just notice your location My Dad is from Mt Carmel PA is the coal mine still burning there??? Last time I was there it was and the town was collasping and everyone was moving out.

On another note the exterior walls are up so I am going to be putting in these after cutting / drilling the holes in and seems some boxes have a beveled edge that makes the light fixture stick out away from the wall and you can see that gap because it is not flush with the T-111. Trying to make it more water tight. I have seen a fewround boxes and they seem to be slight different in size as to the different brands like Carlon and then Pass / Seymour.

Just trying to get the best one that is the smaller of the two in size. It is going to have a feed into one box and then out to a second box for 2 lights on the side of the building. And then one on each side for a total of three. Wire (14-2w/grd) from the switch to these single fixtures.

Thanks I will stop by a supply house and see what they have.


Re: What Size Box for outside Wall Light Fixture???

#1 this is called an E block
#2 make sure there is an inch or so more of surface of the e block face than the mounting plate on the fixture itself

#3 i would avoid silicone, though alot of people swear by it, ive seen more caulking failures with silicone than poly butyl( flex), use a tube of flex or quad, whichever most siding suppliers sell this. set the box into a bead of this then tape off the nailing flange with either red tape or vycor.

now take into into note, if you have siding which requires a rain screen you will have to allow for this with the thickness of the rain screen stock, if using 3/4" stock you will have to nail the block to 1/2" plywood backing, by the time the block goes on and its taped up then the siding goes on, the siding will bulge out if you use 3/4" stock to mount the block to, going to thinner material will allow the siding to run flat

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