Hole Sizes

KentWhitten

I have to template a granite backsplash with (obviously) electrical boxes for the kitchen. I have templated the actual box, but is there a specific size you guys like to see to get those little tabs to clear through? Like a minimum? I need single and duplex box sizes. I guess I'm assuming they are all the same size relatively? I hope?

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Custom Cabinetry - Portland, Cape Elizabeth, Scarborough, Kennebunkport, Yarmouth, Falmouth, Cumberland, Ogunquit, Maine

Salmon Falls Cabinetry

Celtic

What kind of boxes?
Plastic or metal?
New work or old work?

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Magnettica

If the electrical boxes are plastic then cut them out to that size.

If they're metal boxes be sure that the device screw holes are visible after the cut.

If I were you I would install 2" 6/32 screws into the box now so you know your cutouts will make the required clearance.

This sort of things ticks me off big time when done incorrectly.

Good luck!

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KentWhitten

well, it's both really. It's a remodel and there's existing hard plastic ones, the dark brown kind, then they used some blue ones for the new wiring and they also have a metal box or two. I guess my hope that they'd be a std size was not to be. I templated to the corners of the box and am going to expand it slightly. I can't go too far or the dummy plates come out and make me look retarded.

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If you correct your mind, the rest of your life will fall into place ~Lao Tzu

Custom Cabinetry - Portland, Cape Elizabeth, Scarborough, Kennebunkport, Yarmouth, Falmouth, Cumberland, Ogunquit, Maine

Salmon Falls Cabinetry

mdshunk

This is timely, since a countertop man visited a job I was on today to template for a laundry remodel Silestone backsplash. I've never seen the macnine they use in person until today. A sort of "robot arm" that they "beep" lots of points. Pretty cool.

For plastic wall boxes, with the screw ears internal to the box, beep all four corners of the box. For metal wall boxes, with the screw ears external to the box, beep all four corners of the box, and most imortantly... the screw ears. No way to put the screws in or out without the screw accessible. I wouldn't worry about templating big enough to get the device unburied. I generally just bust up the device and rip it out by any means, since new backsplashes mean new devices anyhow. If you template big enough to get the device's ears out easily, the new device's ears will have no support behind them when they're installed on the new backsplash and will be a sloppy install.

In short, just template for the full box height and width, and the screws when necessary, and don't template big enough for the device ears. If I've screwed you up on terminology, I can post pictures.

KentWhitten

OK, so these are the templated sizes. I have 4 different ones. Two doubles and two singles.

single - 2"x2-13/16"
single - 2"x3-7/16"
double - 3-3/4"x3-1/2"
double - 3-3/4"x3"

All width by height, all ballpark. The template is close but not perfect. i'm just trying to get 'er square and be nice to the electrician

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If you correct your mind, the rest of your life will fall into place ~Lao Tzu

Custom Cabinetry - Portland, Cape Elizabeth, Scarborough, Kennebunkport, Yarmouth, Falmouth, Cumberland, Ogunquit, Maine

Salmon Falls Cabinetry

220/221

The mounting screws on a device (switch/receptical) are 3 3/16" apart.

Devices in a 2 gang box are 2 3/4" apart.

Single gang cover plates will cover MAX 3x4 1/2"

Two gang plates will cover MAX 4 1/2" square.

I don't know what the 2 13/16' hole would be for???

I would go wider than 2". The kitchen GCFI outlets are FAT.The plate will cover a 2 1/2" hole easily.

I don't know why the 2 gang boxes would be different. Mud ring on one of them?


As long as your installers have a roto zip....no problem.

Celtic

I don't think so.....

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mdshunk

Sounds like you're trying to do the right thing. Here's a few pictures I just took, which might contain some information valuable to you.

This first picture is of the box extension sleeves that the electrician will use to make the backsplash installation code-compliant, since the boxes are back in so deep. They fit inside the box, so you need a net clear opening for single gang of at least 1.910" wide x 2.920" tall. For double-gang, you need at least 3.720" wide x 2.920" tall.


This second picture is of the typical plastic wall box and an old-school metal wall box. Note that on the metal wall box, you need to allow for the "ears" on each end, so that they are not buried. The plastic wal box is 2.300" wide by 3.670" tall. The metal box is 1.950" wide by 3.600" tall (to allow for the ears).


This third picture is of taking a measurement of an actual receptacle. You'll note the measurement on the calipers is 3.600 just outboard of the screw heads. Go much bigger than this measurement, and the new receptacle's ears won't have anything to rest on. This is the most important measurement, in my opinion.

KentWhitten

damn shunk...thanks. that's perfect. I knew that they had to use those extensions for the granite. Those measurements are fantastic.

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If you correct your mind, the rest of your life will fall into place ~Lao Tzu

Custom Cabinetry - Portland, Cape Elizabeth, Scarborough, Kennebunkport, Yarmouth, Falmouth, Cumberland, Ogunquit, Maine

Salmon Falls Cabinetry

mdshunk

Be advised that some electricians will install "adjustable depth boxes" for new work when they know of or suspect thicker backsplashes. These require a cutout to the full outside dimensions of the box so that the "jackscrew" mechanism can work to jack the box out flush. In my opinion, unless somebody points this type of box out to you, it is beyond the scope of any template man's job to have to identify this type of box in the field. I don't happen to have one on the truck, or I'd take a picture of one for you.

Celtic

Like this:



http://aifittings.com/whnew78.htm

Arlington's "One Box".

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mdshunk

Yeah, that's one type that I didn't give a thought to. Got lots of those on the truck. I was thinking about the blue Carlon one's that have the jackscrew thing-a-ma-jig on the side.

Celtic

This puppy:



Carlon B121ADJ

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mdshunk

Yeah, that's the one I had in my head. That was pretty much the only game in town before the Smart Box/In Box. They're pretty salty too. I think they're around 5 or 6 bucks, wholesale, as I remember. It would be pretty hard for the casual observer, such as a countertop guy, to tell the difference between that blue adjustable box and a regular blue nail on box from the finished appearance. The only real difference is that little screw head in the bump on the left edge.

220/221

You can tweak the cutouts in granite with a rotozip. You need the right bit of course.


I thought the box extensions didn't come into play since the granite isn't combustible??? Wrong again?

mdshunk

In Zodiac you can, but real granite is a lost cause. Corian and Silestone is pretty much butter.


Hmmm... that's sorta ringing a bell. Let me check quick. You may well be right, but I still use them anyhow.

Magnettica

Those adjustable boxes rule.

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mdshunk

Here we go. You get up to 1/4" if the wall material doesn't burn, and must be flush if it does.

314.20 In Wall or Ceiling. In walls or ceilings with a
surface of concrete, tile, gypsum, plaster, or other noncombustible
material, boxes shall be installed so that the front
edge of the box will not be set back of the finished surface
more than 6 mm (1⁄4 in.).
In walls and ceilings constructed of wood or other combustible
surface material, boxes shall be flush with the finished
surface or project therefrom.

I'll confess that I go over the 1/4" every once in a while. If the factory device screws reach, then I don't use a box sleeve. If I have to switch them out for longer screws, that's my que to use a box sleeve.

A W Smith

Ir sounds like hes describing the old Bakelite boxes from the late fifties/early sixties.
'brown hard plastic"

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Al Smith
http://www.awsmith.com