Shop Sweet Shop #2: Let There be Light

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Blog entry by magaoitin posted 09-19-2016 11:01 PM 1445 reads 1 time favorited 2 comments Add to Favorites Watch
« Part 1: In the beginning there was an empty shop Part 2 of Shop Sweet Shop series Part 3: Shop Heating – Gas or Electric? »

I had the first two parts of my build written up, so this makes for a quick second post. We will see how long it takes me for future posts.

After demoing the Bathroom area and a few benches on the “ground” floor, I think I found where the power had come into the shop. It was obvious that someone had run an underground line from the electrical panel in the front of the house, under the house through the backyard, and up into the shop at some point.

However after crawling under the house I could not find any cables that might be able to carry enough juice to service a shop. In the flip of the house, the main panel was upgraded, and it would make sense that all of the old cables that were easy to get to were most likely cut out, so the inspectors wouldn’t write it up.

Months later, after I started to dig up the backyard for my gas line, I found a couple of cables that might have been part of the power (and cable TV) to the shop, though they were only about 6” down. Again attesting to the quality of construction this place obviously flew by. If you don’t want to permit something and do it “by the book” okay, fine that is your choice, but really what is an extra day of digging to do it at least close to the right way?

Even if I could have gotten my dream of 3 phase to the shop, I was going to need single phase power no matter what.

If I fed the shop from my house panel, the distance from the front of my house (where my main panel is set) to the closest wall of my shop is about 65-70’ in a straight line, add in the ups and downs, and I was looking at the 90-100 range.

To DIY it, I was looking at around $400 for aluminum 4/0 wire UF or SER wire, plus the digging and crawling under the house. And ultimately I would have a 125 amp service with very few dedicated 20 amp circuits. I might end up with (3-4) 240 amp double pole, (4-6) 120v, and 2-3 lighting circuits. I didn’t feel this was enough for a 900 sq ft dedicated shop. And for whatever reason I am not a fan of a bunch of thin double-breakers (though I did use some in my panel)

I cannot stand having to unplug one tool to plug in another. So that means a receptacle on almost every stud. And unless you want 6 pieces of equipment on one 20 Amp circuit I wanted a bunch of circuits. Even though it si just me in the shop, and I cant run 2 pieces of equipment at once, I was thinking of the future or if this was a functional auto shop for someone. I also have a few friends that will more than likely want to come over and work on projects once this

More talks with the power company on permitting, and a dedicated overhead service to the shop would be in the neighborhood of $600 by a pole on the side street instead of from the front of the house, 200’ away…If the existing transformer on the pole could support another service.

Of course it couldn’t. The transformer was maxed, and was not scheduled for an upgrade-replacement in the near future. So the deal would be that I pay for the labor to upgrade the transformer and the power company would supply the new transformer for $750.

$400-$600 for a 100amp-125 amp subpanel or $1400 for a dedicated 200 amp panel.

I decided on a dedicated 200 amp service dropped to the shop, so it is not hooked up to the house. I figured that this would help if I ever decided to sell the house; or if I get tired of woodworking I can rent the shop out and not have to be concerned with separating an electrical bill. Total cost was $1400 for a 200A service to the meter.

Yea! Power to the shop, and soon, no more extension cords through the back yard.

I did all of the wiring myself, with the exception of the wire from the meter base outside, to landing it on the panel (about 5’). I bought the wire and had everything I needed, but ended up getting distracted by other things in life. After this sat for about 6 weeks of me not doing anything, so I hired out this connection. As an added bonus I asked the electrician to “inspect” the work I had already done and write up any code deficiencies he might find, before I called in for my inspection. He said the install looked good and didn’t find anything that I would get dinged during my inspection. However he did question why I had run the wires the way I did. After I explained it he shrugged his shoulders and said “okay, well good luck with that…”

I did things a little…differently…when it came to running power. Actually every one of my friends thought I was mentally unstable for doing what I did as it did not make sense to any of them, even with drawings, but you can be the judge. It is one thing to see it on paper, and another to see it in real life (or photos after it is done).

I still maintain that this allows me a great level of flexibility with a unique look/application. I did not want surface mounted electrical lines, however, I did want to be able to move or add receptacles. Add to this that I really wanted a very clean interior space, and it had to be something a bit nontraditional.

I tried to devise a way to run the romex in such a way that it will be easily accessible, so when I needed or wanted to move circuits around, it is as simple as possible, and I am not tearing out plywood or drywall, or fishing romex down insulated walls. To this end I decided on running a horizontal electrical chase.

For the finished wall:
  • The bottom 4’ will be full sheets of CDX plywood with no receptacles (actually I ended up with (2) below 4’ but they have a specific purpose that I cannot anticipate ever moving.)
  • The 12” space from 48” to 60” AFF is going to be my electrical chase, with removable 4’ long MDF panels and removable insulation
  • The remainder of the wall will be reclaimed cedar from past fencing projects. With the eve height of around 13’ it makes for an 8’ dimension above the MDF on my short walls.

After a little insulation it is a little clearer, maybe..

Cut out “plugs” of insulation to make it removable in the future

I ran two dedicated 120v receptacles as well for the future air compressor and dust collector. One is a 30A on a 10 gauge wire (in the off chance I need to switch out to 240V) I knew I wanted these outside someday so prepred for them now. Weather tight boxes, however the 30A receptacle is not a GFCI. I didnt land the wire in the panel it is only for future, and was easy enough to run the wire now.

I called for the electrical hookup inspection (from the panel to the meter and up the service mast). The inspector was fantastic, and she actually called in the approval to their connection department for me, and the next day while I was at work she called me and told me the connection was done and I was good to go. Some inspectors are fantastic. I have had my share of horror stories with a lot of them, but I cannot say enough good things about how great my power has been to work with.

I had one missing run of conduit and a big piece of work I still wanted to do in the grand scheme of things, but I did not have the RI started when I called for my inspection. I actually just called for the Connection Inspection to get power landed, but I was so far along with the install that the inspector signed me off for all Rough-In.


While roughing in for electrical in the walls, I changed my mind about where I wanted equipment and how I was going to get power to the middle of the shop. Originally I was going to run power down one of the columns for the loft and have a cord from there to the table saws in the center of the shop.

The Loft area is only 8’-10’ wide along one wall, so I had a couple of columns to work with that were within about 5’ of the shop’s center. This is also where I would have run duct work for the dust collection, but figured in for a penny…

I decided I wanted to have an electrical floor box instead of overhead power or a drop. Since I would need to sawcut the concrete to run the conduit…well what’s the difference between a 4” wide cut for a conduit and a 10” wide trench that could hold more????


Cost-wise it was going to be the basically the same to demo out and dispose of the concrete up to 12”-14” wide as it would be for a 4” trench, so I decided to add in an underground line for my future dust collection.

The rental of a 14” walk behind sawcutter was $75 for a half-day and then a 60-70 lbs jackhammer was $60 for a half-day rental.

Disposal was a flat $25 at a concrete recycler near me for a pickup load. I just had to make sure there was no rebar in it. That went to a metal recycler for free.

I had no idea how well the slab was built, but everything else was a bit hill-billy, so I did not think I would run in to much, if any, rebar when demoing the slab. Famous last words.

The first 5’ lifted up right away, but after that I couldn’t get anything busted out. It would wiggle and I could lift it about 1/2” but no further, I wonder why…

The Bosch Bulldog rotohammer was not going to cut it

The next weekend I rented a 65lb jack hammer and had everything broken out in about 45 minutes. As you can see there was (1)! piece of rebar running right down the middle of my sawcut, that was holding everything together.

Another trip to the rental store…

30 minutes later

The slab ended up being about 4-1/2” thick in the middle of the shop, but quickly jumping up to around 5-1/2”-6”

Now for the electrical floor box

Since I do a lot of commercial construction I decided to buy a commercial grade (Hubbell B4333) cast iron and brass (3) gang floor box. It is adjustable after you pour the concrete as well to level and raise the rings. instead of the cheap plastic ones they sell at the box stores. In hindsight (and frustration) I should have installed (2) 3/4” conduits, instead of trying to put everything in one.

The box was $100 on eBay, Each brass cover plate was $15, also on eBay, but I ended up buying from 3 different sources. Total cost was around $150.

A friend gave me a truckload of 6” spiral duct left over from his conversion to 8”, so all I have to buy are fittings, elbows, reducers, duct seal, etc. Since dust collection is down the road for me this is all in storage the loft space, with the exception of (2) straight pieces. The 90°’s are new and shiny.

This is literally going to be cast in stone, so dont forget the duct seal.

Screw and glue the joints together. I do not want these joints coming apart when I pour the concrete

Now to make it grey.

I had planned on (2) 240v and (1) 120v receptacles at this spot (which would be (6) #10 THHN and (3) #12 THHN wires. This would be fine in a ¾” conduit, but during this project I picked up an Oliver 10” table saw which is a (4) wire 240v plug and not the (3) wire 240v my Delta Unisaw uses. That extra #10 wire made a world of difference in pulling.

I know I am right at the max for what can go in a 3/4” conduit. Per the NEC when you have more than 2 conductors you can only fill the pipe to 40%. I know from somewhere that ¾” PVC conduit (sch. 40) can hold (9) #10 THHN’s or (15) #12 THHN’s. These are pretty common gauge wires and conduit size I see all the time at work
Using two different sizes gets a bit trickier. At a quick glance, (7) #10 and (3) #12 is close. The calculation is:

.0211×7 = .1477 #10 THHN’s
.0133×3 = .0399 #12 THHN’s

0.1876 sq in of conductors

NEC, Chapter 9 Table 4, conduit fill for Schedule 40 PVC using 2+ conductors is 0.203, (40% fill) and I am at 37% of fill. Pulling the wire sure seemed more like 80%

Sorry about the math and electrical technical jargon, but it was something that went into this build and is applicable for the electrical nerds out there (and that a simple wood butcher can figure out electrical and mechanical stuff on their own without having to hire a “professional.”)

As a side note I have come to the opinion that I have too much stuff (George Carlin would not be impressed) Tools, equipment, and casework waiting for this space to be built, that I have the entire area under the loft, 10’ x 20’ stacked floor to ceiling. When I want to work on that side of the shop, everything has to move. If I had rented a storage space for 6 months for all my big tools and casework, the overall time it took to remodel would have been cut in half. As it was, I moved everything I owned back and forth across this shop dozens of times.

-- Jeff ~ Tacoma Wa.

2 comments so far

View gargey's profile


1013 posts in 1551 days

#1 posted 09-20-2016 12:03 PM


View Bigrock's profile


292 posts in 3737 days

#2 posted 09-23-2016 02:30 AM

You made the right chose in going with the 200 amp box. Enjoy your new shop.

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