# Cutting a hole for an electrical box



## eagertolearn (Jan 13, 2010)

I recently purchased a home and need to do some work on the wiring. It was built in the mid 60's and the walls appear to be 3/8" drywall with 3/8" plaster over the drywall. How do i cut through this to put in a junction box?


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## canadaclub (Oct 19, 2006)

a drywall saw


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## racebum (Mar 8, 2010)

and or a rotozip


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## eagertolearn (Jan 13, 2010)

canadaclub said:


> a drywall saw


I didnt have any luck with a drywall saw the plaster was chipping real bad and i couldnt make a clean cut. Thats when i posted my question on here.


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## Axecutioner-B (May 18, 2010)

A small (4inch) grinder with a diamond blade will cut plaster with clean cuts but VERY dusty.


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## bjbatlanta (Jul 16, 2008)

Recip saw (or jig saw) with a metal blade should cut it without chipping the plaster. If you have variable speed. slower is better....


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## Daniel Holzman (Mar 10, 2009)

There are special blades designed to cut plaster that can be used with a jigsaw. They have sintered carbide or diamond chips on the blade, they cut well, and do not deteriorate nearly as quickly as a metal cutting blade. Plaster is tough on saw blades. The drywall blades can be purchased at a big box store.


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## oh'mike (Sep 18, 2009)

Those new multi tools are very handy for this exact purpose---Dremel makes one--Harbor Freight has a cheap-o that has gotten good reviews---not dusty--very easy to use.


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## Red Squirrel (Jun 29, 2009)

While a drywall saw is a bit tricky to use, I find the trick with them is to go fast, if you start to slow down you get stuck. I tend to try to use just the tip since I don't know what's on the other side.

Exacto knives work nice too but are more tedious, you almost have to hold something on the end so you don't cut too far. Once a cut is made then you can punch the piece out.

I've used a jig saw with a regular wood blade which I had cut so it's the perfect size for drywall, to demolish my whole basement. It went rather well and not too much dust.


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## fetzer85 (Dec 4, 2009)

If you just had drywall then a drywall saw would work fine, but I understand what you're saying about the chipping plaster. When I did this I first traced where I wanted the outlet, then drilled a 1/4" hole in each of the 4 corners, then as others have mentioned I used a jigsaw with a carbide blade to cut out the actual box shape. It worked very well, no significant chipping. If it does chip on you, you may be able to cover it up with an 'oversized' recepticle plate.


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## paulyg (Jan 26, 2010)

My house is built the same way. I have rewired most of the house and this is the procedure I've come up with. Stumbled upon this methodology b/c I thought walls were plaster & lathe when I first moved in.

Measure and draw your cut lines in pencil
Put painters tape along outside edge of each line
Make a few passes along each line with a razor blade. The idea is to get most of the way through the white top coat of the plaster.
Drill a 5/8" hole in one corner of your box. This will make a lot of dust.
Cut the rest with a drywall saw.

You could also use a dremel/rotozip in lieu of the last two steps. I'll do this if I have to cut a hole bigger than two gang device box.


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## Godkin (Jul 23, 2010)

I would buy deep-cut in boxes with a pair of F-clips. then I would trace the box where i would like it to be. then I would get a drill, drill bit big enough to allow the drywall saw to fit in and start cutting. i would cut a hole in the middle of the trace to allow my finger to fit in and feel around to make sure the rest of the traced area does not land on a stud. if it does move trace over but not past the hole if possible. if no stud i would then drill out four corners of trace so you can fit the drywall saw in and cut straight lines. then i would fish wire and then mount the box and secure with fclips and Finnish the rest of the job.






eagertolearn said:


> I recently purchased a home and need to do some work on the wiring. It was built in the mid 60's and the walls appear to be 3/8" drywall with 3/8" plaster over the drywall. How do i cut through this to put in a junction box?


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## Thurman (Feb 9, 2009)

I've used "paulyg"'s idea around here on the same type walls with much success. I just don't use a 5/8" drill, maybe a 3/8" drill, your preference. I do use a jig-saw blade made for cutting plaster _without_ metal lath. I think the important trick here is to tape and score carefully, take your time and it will make a smooth cut. David


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## Willie T (Jan 29, 2009)

oh'mike said:


> Those new multi tools are very handy for this exact purpose---Dremel makes one--Harbor Freight has a cheap-o that has gotten good reviews---not dusty--very easy to use.


If you have not tried one of these yet, please do so. They are fantastic. I couldn't justify the $400-$500 for the Fein Multimaster, so I shopped around.

I ended up with the Craftsman battery powered job. $100, and they give you a full compliment of their tools with it. But you do need to buy the extra battery due to having only exactly 20 minutes of juice per recharge. But you can get a lot done in 20 minutes of motor operation.


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## Willie T (Jan 29, 2009)

Here's a little tip for keeping your drilling or sawing clean.

Drape a damp towel over the edge of a small trash can.
Hold the can and towel solidly against the wall just below where you intend to drill or cut.
As you create dust from the drilling or cutting, it will fall onto the top edge of the towel.
Slowly, but progressively slide the can down the wall as you drill.
The towel will roll into the can as you go down the wall, taking almost all the dust and shavings with it, depositing it all in the can.

All that will be left for you to do is give the wall a final, quick wipe with the clean side of that same towel.

Mama will be happy!


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## Gary in WA (Mar 11, 2009)

Good idea! I tape some paper/tape with my *painter's masker tool* to the wall just below the hole with the corners pinched and taped up to catch it. Throw away is quick and easy. The H.F. multi-tool (electric) is quick and easy, also for cutting/patching base and casing while in place.

Be safe, Gary


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