# What size hole saw for 4" Square Box Fixture Cover



## kornbln (Apr 4, 2008)

I'm installing some light fixtures using 4" square boxes with a fixture mud ring (RACO 756). What size hole saw do you guys typically use to cut a hole in siding, etc for such a mud ring? I've experimented with 3-1/2" which works, but leaves quite a bit of play. I also tried 3-1/4" which seems a bit better but not as snug as I'd like. I might try going down to 3-1/8" but that size doesn't seem to be as readily available. Does the 1/8" rule come into play here?

The width of the raised portion of the mud ring is sort of hard to measure being that it is slightly tapered.


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## paul d. (Jul 13, 2008)

are'nt you gonna cover it anyways ?? as long as its a fairly snug fit it should work. i think.


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## MDShunk (Jan 7, 2007)

The round mud rings for 4-squares are the old 3-1/4" size. I'm not sure if I even have a 3-1/4" hole saw, so I use my 3-5/8" hole saw.


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## EBFD6 (Aug 17, 2008)

paul d. said:


> are'nt you gonna cover it anyways ?? as long as its a fairly snug fit it should work. i think.


I agree with Paul, as long as the hole is close the fixture canopy should cover any slop in the hole size.


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## 480sparky (Sep 20, 2007)

MDShunk said:


> .......I use my 3-5/8" hole saw.


Same here. I use the Lenox "Master-Grit" carbide version.


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## MDShunk (Jan 7, 2007)

EBFD6 said:


> I agree with Paul, as long as the hole is close the fixture canopy should cover any slop in the hole size.


Yeah, fixture canopies are normally at leat 4-1/2 or 5 inches round.


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## egads (Sep 1, 2009)

No mater what size the gap is, caulk it.


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## John Valdes (May 17, 2007)

egads said:


> No mater what size the gap is, caulk it.


Whats caulk?


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## egads (Sep 1, 2009)

A waterproof filler and sealant used in building and repairs


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## kornbln (Apr 4, 2008)

Does the 1/8" gap rule only apply to plaster?
*
3-1/2"* hole:









*3-1/4"* hole:









Lenox does make a 3-1/8" hole saw which looks like it might work. I'm a perfectionist =\


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## MDShunk (Jan 7, 2007)

I don't see a gap on either of those. They both have metal behind them.


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## kornbln (Apr 4, 2008)

MDShunk said:


> I don't see a gap on either of those. They both have metal behind them.


I didn't think of it in that way. I was counting on you providing something from the NEC to justify going to the trouble of getting the next size down hole saw to satisfy my sickness.


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## MDShunk (Jan 7, 2007)

kornbln said:


> I didn't think of it in that way. I was counting on you providing something from the NEC to justify going to the trouble of getting the next size down hole saw to satisfy my sickness.


Hey, I'm right with you. If I used round mud rings sufficiently often, I'd probably want to own a 3-1/8" hole saw too. I just don't use them that often, is all. I think mostly for exit signs in suspended ceiling tiles.


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## kornbln (Apr 4, 2008)

So I went ahead and got a 3-1/8" hole saw. Perfect fit. Here's the result:


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## ralpha494 (Oct 29, 2008)

I gotta say thanx for the follow up. Thanx.


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## 480sparky (Sep 20, 2007)

kornbln said:


> So I went ahead and got a 3-1/8" hole saw. Perfect fit. Here's the result:


Silly question, but why didn't you just use a tape measure to find out what size it was?


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## kornbln (Apr 4, 2008)

480sparky said:


> Silly question, but why didn't you just use a tape measure to find out what size it was?


I think I initially tried to, and came up with 3-1/4"... But like I said in my original post: "The width of the raised portion of the mud ring is sort of hard to measure being that it is slightly tapered."


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## kornbln (Apr 4, 2008)




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## 480sparky (Sep 20, 2007)

*Using math*


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## kornbln (Apr 4, 2008)

480sparky,

Never thought of doing it that way!


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## 220/221 (Sep 25, 2007)

> I was counting on you providing something from the NEC to justify going to the trouble of getting the next size down hole saw to satisfy my sickness.


Let it go man, just let it go.

Construction isn't the place for anal compulsive behavior.:thumbup:


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