Wall cut-outs

[Jon Snider]

Running wire and installing outlets in my shop now. I haven’t decided yet if walls will be plywood, T1-11, or SmartSide. Leaning away from drywall.

What is is best way to cut out the numerous holes for switches and receptacle boxes assuming something other than drywall? RotoZip still work, vs trim router or maybe jig saw or Sawzall?

thanks and happy new year to all,

jon

[Robert Engel]

This doesn’t answer your question, but when I built my shop the electrician suggested surface mounted boxes and conduit.

I’m really glad I did that makes adding, adapting circuits a snap.

Plus (to your question) no box cutting out!

[Andrew Seemann]

To not answer your question again, I did drywall with Romex for my first shop with outlets mounted in the wall. For my second shop I did OSB and surface mounted conduit. If for some reason I ever do a third shop, it will be OSB or plywood walls with surface mounted conduit. Installation was about the same amount of work, and it is way easier to modify later on, which you probably will do no matter what. I would never do drywall for shop walls again. Being able to easily hang anything anywhere is too convenient.

To answer your actual question. When I have had to do openings for boxes in OSB or plywood, I drilled holes in opposite corners and used a Bosch jig saw. This is prefaced by a lot of measuring and figuring and occasionally followed by a lot of swearing.

[John K Jordan]

I used 1/2" ply on all interior walls and ceilings. I made all cutouts by carefully measuring, drilling two holes to touch both lines in opposite corners using a bit big enough for a jigsaw blade, then cut the rectangle with the jigsaw. I cut outside the line to allow a bit of slop for easier fit.

I think the sawzall would be harder to control than the jigsaw. I wouldn't use my RotoZip on anything other than sheetrock and even then a hand saw is better. I can't see using the trim router for this since the jigsaw is fast and sufficient.

Another easy way for plywood is to run the wires but no boxes in the wall, cut the rectangle well between the studs, and use old work boxes after the plywood is up. I wouldn't use this for flimsy wall covering in a shop. I don't know if this would be allowed if it needed to be inspected.

BTW, I put up all my plywood with screws so I could take down panels if needed. I did use leftover Smartside in the maintenance area of the shop and it's fine.


Running wire and installing outlets in my shop now. I haven’t decided yet if walls will be plywood, T1-11, or SmartSide. Leaning away from drywall.

What is is best way to cut out the numerous holes for switches and receptacle boxes assuming something other than drywall? RotoZip still work, vs trim router or maybe jig saw or Sawzall?

[Tom M King]

I never cut them out in place. They are cut before the piece of whatever is put up.

My preferred method is to not fasten any boxes to studs to start with. They can still be placed right beside a stud, but I will just pull the wires, then pull them into the box as it's slid in after the finish wall is up.

For 120v receptacles, I use the heavy duty, plastic old work boxes. They get mounted into the wall panel/sheetrock, and a bead of construction adhesive run all the way around it on the back of the panel, before the panel is put in place. If it's something like the Smartside, I place them where I want them without regard to fastening to a stud. Pull the wires into the box as you put the panel in place. I don't like the cheap boxes, but have never had a problem doing this with the heavy duty boxes.

I hate oversized cover plates, so this also allows the use of standard sized covers. Another thing allowed by the old work boxes is that they are automatically at the exactly correct relationship with the wall surface. That allows the device to have a secure attachment, which doesn't let it move around. I hate devices that move even more than oversized cover plates. Also, on panels like the Smartside, it lets you put the box where the cover won't span one of the grooves. It also lets you put switches a little farther from studs framing door openings, which is especially helpful if you're planning to use wide casing.

When putting the panel in place, and pulling the wires into the box, I break out the little trap door clamps with needle nosed pliers, to make it easier to get the wires in, and caulk the hole once everything is in place, with some of the leftover fire caulking. The construction adhesive around the back of the box edge, and the caulking in the wire holes make it an airtight fitting to the wall.

I also run a groove in the sole plate to pull wires so they don't interfere with installing the insulation. You have to pull wires that turn corners when setting the corner posts though. I've never met an Electrical Inspector that didn't like this method, but there is always some explaining to do to a new one when they come for rough-in inspection, and there are only wires stapled to the studs.

A piece of plywood the right size for the cutout stays in my "Electric" toolbox to mark where I want the opening for the box.

[glenn bradley]

I did in the wall with stud mounted boxes. I used a jig saw for the cutouts prior to mounting the panel. I used OSB, primed and painted semi-gloss white. What a boost in light and reduction of shadows! As usual, Tom's experience shows its value time and again. If I do it again, I will follow his method of quality old-work boxes. This sounds like the hot ticket. BTW, I screwed the OSB to the studs and have taken panels down to add additional outlets. No big deal. I do used a cleat wall for hanging fixtures. One of the best ideas I ever read for shop walls.

[Peter Christensen]

My shop has 1/2" OSB sheathing. I used Blind Mark (https://www.calculated.com/products/21/Blind-Mark.html) tools to find the cutout locations to jigsaw. It keeps the mistakes from measuring and marking from happening when you are working alone. I'm not a pro board hanger so it was money well spent for me. Their video's show how they work. I differed from their method by marking the locations then cutting off the wall.

[Bill Dufour]

I paneled the wall behind my woodstove with hardi panel because it is fireproof and it was the closest match to the existing Masonite paneling from the 1970's. I used plywood with a cutout and a router with a guide on it with a 1/4" spiral endmill. That job looks good but man that stuff is heavy. It was only three sheets but every piece had at least one cutout or notch around the door. I aslo used my diamond wet blade little skilsaw from harbor freight. All cutting was done outdoors to avoid dust and then mud. I washed the panels off after cutting to remove the dust.
Bill D.

[Jim Becker]

I do it the way that JKJ mentioned up above...carefully measuring and cutting prior to installing. That said, I've since switched to surface mount for anything I've added or changed. If I built a new shop, other than some 120v convenience outlets that might be in the space regardless of use, I'd go surface mount conduit/raceway for sure because of the flexibility. I've made quite a few changes over the years in my shop so I know it would happen in the future, too.

[Martin Wasner]

This doesn’t answer your question, but when I built my shop the electrician suggested surface mounted boxes and conduit.

I’m really glad I did that makes adding, adapting circuits a snap.

Plus (to your question) no box cutting out!

Another vote for surface mount.

Got an outlet two feet too far away? Move it. Real simple.

Got a pipe, but need a different voltage? Pull it.

Think ahead, pipes crashing into stuff is a pain.

[Jon Snider]

Thanks everyone. When I wrote Sawzall I actually meant to say Multi tool. Seems like this might also be a good option vs a jig saw, esp using the Blindmark system.

[Brian W Evans]

You didn't say what kind of shop you're talking about - stand-alone, garage, basement... I believe code in most places doesn't allow plywood or similar on walls shared with the main living space of the house. For fire safety reasons, this needs to be drywall - and 5/8 drywall if its a wall shared with a garage. Maybe it's not this way in CO, but I think this is pretty universal.

In my garage, which is attached to the house, I have the 5/8 drywall on the shared wall and 1/2 ply on the other walls. I like being able to hang things wherever I want. I also hate working with drywall.

All the outlets I have added have been surface mounted EMT and boxes. This is very easy to do and very flexible. I would for sure do this again.

[Frank Pratt]

I used a Rotozip on the 13/16" OSB that my shop walls are lined with. It was a lot slower than with drywall, of course, but worked well. & was faster than measuring & pre-cutting the holes.

[Jon Snider]

You didn't say what kind of shop you're talking about - stand-alone, garage, basement... I believe code in most places doesn't allow plywood or similar on walls shared with the main living space of the house. For fire safety reasons, this needs to be drywall - and 5/8 drywall if its a wall shared with a garage. Maybe it's not this way in CO, but I think this is pretty universal.


It’s a detached stand alone shop.

[roger wiegand]

When I've had to do it I use a jigsaw, but in my shop everything is surface mounted. I did spray foam to seal the walls in the old barn which makes running wires inside the wall harder.

[roger wiegand]

You didn't say what kind of shop you're talking about - stand-alone, garage, basement... I believe code in most places doesn't allow plywood or similar on walls shared with the main living space of the house. For fire safety reasons, this needs to be drywall - and 5/8 drywall if its a wall shared with a garage. Maybe it's not this way in CO, but I think this is pretty universal.


I'm pretty sure that fire-rated plywood would meet the code requirement.

[Tom M King]

I found a picture of the type of installation I was talking about in sheetrock.

[Roger Feeley]

This doesn’t answer your question, but when I built my shop the electrician suggested surface mounted boxes and conduit.

I’m really glad I did that makes adding, adapting circuits a snap.

Plus (to your question) no box cutting out!

+1 on surface mounting. As Robert said, adding and moving stuff is easy.

With just a few exceptions, all my machines are wired up to the ceiling. I'm tall enough that it's easy for me to reach ceiling mounted outlets. If I were shorter, I would just wire up hanging boxes. I don't use extension cords much. If I find that I am running a cord someplace, it just means that I need another outlet.

For those that are wired to the wall, I use numerous clips to hold down the romex. I used to run conduit but my shop is just me and I know enough to treat the romex gently.

One more hint. Mark the breaker number on all the outlets. I write stuff on the breaker box but sometimes there are too many items to do it neatly.

[David Gutierrez]

no such thing as "FIRE RATED" plywood. there is a fire retardant treated plywood.

[Jon Snider]

Any feedback on how a RotoZip works and feels on 10mm SmartSide? Seems like it might be better than regular plywood and less likely to cut into plastic boxes.

Thx again

Jon

[Jim Andrew]

I found a rotozip very difficult to use on drywall, and prefer to use a saber saw. Can't comment on smart side.

[James Biddle]

we ran wire mold around the shop...mix and match various plugs and switches wherever you want.

[Jerome Stanek]

When I was installing CVS stores I had to cut outlets in 3/4 paneling and I used a roto zip just have to use the right bit.

[Orlando Gonzalez]

I have the wiring running through the studs and stud mounted boxes. If I had to do it again, I would go with surface mounted boxes. I used a jig saw to do the cut outs. I drew the outline on the wall panel before attaching it to the studs. If you are doing stud mounted boxes make sure that it protrudes far enough to account for the thickness of the wall panel. I had to move too many boxes to accomplish this. It became so frustrating that I left two on the ceiling as they are. The reason I did it was because the cutouts were to be covered by wall plates for aesthetics only.

[Julie Moriarty]

On the rare occasion walls are sheathed in something other than drywall on the jobsite, I've seen both measure and pre-cut and a router used. Carpenters do the measure and pre-cut, drywallers use a router.

[Roger Feeley]

I have the wiring running through the studs and stud mounted boxes. If I had to do it again, I would go with surface mounted boxes. I used a jig saw to do the cut outs. I drew the outline on the wall panel before attaching it to the studs. If you are doing stud mounted boxes make sure that it protrudes far enough to account for the thickness of the wall panel. I had to move too many boxes to accomplish this. It became so frustrating that I left two on the ceiling as they are. The reason I did it was because the cutouts were to be covered by wall plates for aesthetics only.

orlando, your comment about wall plate aesthetics reminded me of something else I did. In my basement shop, all outlets with plastic plates were put in by the electrician and are powered from the main panel. All outlets I put in have galvanized plates. I’ve found that very convenient compared to my old shop where I just used whatever was at hand.

another thing I did was to avoid those $.99 outlets where you insert the wire in the back. When I deconstructed the old shop, a bunch of those thins had come loose and were probably arcing. It’s a wonder that I didn’t have a fire. The new outlets are backwired with clamps.

[Orlando Gonzalez]

Roger, all electrical work was done by an electrician who put the galvanized plates on the boxes. After I put up the plywood walls with the cutouts, it looked pretty bad so I decided to cover up the cutouts with white wall plates to match the wall color. That's the aesthetics part. It was then that I realized that the boxes were too far in. I got mud rings to replace the galvanized plates then attached the wall plate to it and then the fun began moving the boxes out so that the plate would be flush with the wall. Huge PITA and why surface mounted would have been my best option.

[Jerome Stanek]

When I was installing I would measure and cut before I put the paneling up the outlets were already there and wired up.

[Scott T Smith]

There are a few things that I did when I built my shop that have worked out well.

First, I ran several 3" conduits under the slab from my load centers to each wall. The conduit stubs up inside the wall into a box, and then there is a horizontal run of 1-1/2" conduit runs through the wall with numerous electrical boxes set along the conduit inside the wall. This allows me to easily pull wire to almost any location in the shop walls in the future to accommodate any changing equipment configurations.

Second, I have four load centers in my shop. A single phase 240 load center primarily filled with 120V breakers, a single phase 240 load center primarily filled with 240 breakers, a 240 three phase load center and a 480 three phase load center. All are connected with 6" rectangular conduit running below them, and most of the conduits in the shop terminate into the rectangular conduit. It's a flexible configuration that makes it easy to upgrade equipment and pull new wire.

Third, the bottom 4' of my shop has 5/8" drywall all the way around, and OSB above it. This places fire resistant drywall adjacent to all of the electrical components, as well as down low on the walls near where any fire might start, yet allow for the versatility of the wooden walls above for mounting shelves, hanging tools, etc.

[Jon Snider]

Scott and others,

This is all excellent information. Thanks so much for the help. In earlier posts I incompletely described my new shop. It is 40 x 28’ over a structural floor (beefed up to industrial standards) over a full basement. This leaves me lots of flexibility for future wiring changes and also allows me to place the 3 Phase generator, plus dust collector and air compressor down below. After reading this thread, I can now add additional receptacles, of any voltage or phase, via in wall-to-basement conduit to numerous extra empty metal in-wall JB’s mounted in multiple spots around all four walls. If in the future those don’t cut it, surface mounts via basement are an easy solution.

I wanted to to follow up after partially putting up 7/16” SmartSide. Using a RotoZip didn’t work out well for us. Couldn’t easily feel the SS OSB vs the plastic box.

Peter, the Blind Mark was a great call. So far seems to work great, as long as you remember to place the magnet arrow up. There’s a nice 2” repair in the one where I forgot. Thanks much for the tip!

I may try the lipstick on the rim of each receptacle box trick for the panel with 7 cutouts just to see how it works.

Once again, this is a great site. Good people. Great knowledge.

Picture of southwest corner. This area is 10’ tall with a loft overhead. Don’t have any pics yet of east and west walls with most of cutouts:
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North wall with a 16’ rake, will be a challenge. Saving it for last.

Jon

[Jim Dwight]

The walls of my last two shops are OSB which I skim coat with drywall compound and paint with cheap white ceiling paint. The skim coat helps a lot with the rough surface of the OSB. Three shops ago I has surface wiring but the last two have been in the wall. I don't change a lot so it works fine. I just added a circuit for a dust collector and it wasn't too bad. I put a guide up and ripped the top foot of the OSB, pulled it, ran my wire, put it back and skimmed it again.

[Jim Becker]

That's going to be a wonderful space!

[Lyndon Klassen]

There are a few things that I did when I built my shop that have worked out well.

First, I ran several 3" conduits under the slab from my load centers to each wall. The conduit stubs up inside the wall into a box, and then there is a horizontal run of 1-1/2" conduit runs through the wall with numerous electrical boxes set along the conduit inside the wall. This allows me to easily pull wire to almost any location in the shop walls in the future to accommodate any changing equipment configurations.

Second, I have four load centers in my shop. A single phase 240 load center primarily filled with 120V breakers, a single phase 240 load center primarily filled with 240 breakers, a 240 three phase load center and a 480 three phase load center. All are connected with 6" rectangular conduit running below them, and most of the conduits in the shop terminate into the rectangular conduit. It's a flexible configuration that makes it easy to upgrade equipment and pull new wire.

That sounds amazing. Do you have pictures.

[Scott T Smith]

That sounds amazing. Do you have pictures.

This is the only one that I have stored on this computer. It shows the wall with the electrical panels during construction.

From right to left is an 800A 480VAC 3 phase panel, a 400A 240 3 phase panel, a pair of 240 single phase panels, and on the far left is a 480V transfer switch.

Underneath the load centers is a horizontal run of 6" rectangular duct that connects all of the electrical infrastructure together. In the room behind the 480V panel is a 400HP generator, a three phase step down transformer (480 to 240), a 30HP rotary phase converter and a transfer switch that lets me choose between generator or line/phase converter power for the 240 3 phase panel. All of this is also hooked into the 6" rectangular duct.

If you look closely you can see the conduits coming out of the slab and terminating into the rectangular duct. Most of the 3" conduits are hidden behind the sawhorses.

Basically I can run wire from the panels to anywhere in the shop walls via the conduit infrastructure. This came in handy recently when I upgraded the small dust collection system from a 3hp single phase to a 5 hp three phase blower, and also upgraded the air compressor from 7.5 hp single phase to 10hp three phase.



402180

[Lyndon Klassen]

Scott Smith

You must have very different rules than me. I couldn't interconnect 3 different systems like that. My inspector would shut down the job if I tried that.