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Thread: Floor electrical outlets

  1. #31
    stub a piece of 3/4 steel ridgid conduit up through floor. securely fasten it the floor joist below so it cannot move. then screw an aluminum bell box onto it . you could even put an in use outside rec cover on it if you were really concerned about sawdust

  2. #32
    Quote Originally Posted by ray grundhoefer View Post
    stub a piece of 3/4 steel ridgid conduit up through floor. securely fasten it the floor joist below so it cannot move. then screw an aluminum bell box onto it . you could even put an in use outside rec cover on it if you were really concerned about sawdust
    A single conduit is not suitable for support of a box, either a 2nd conduit or other means of support would be required.

  3. #33
    Yes I know, been an electrician for 40 years. Silly thing is all you have to do is attach box to floor with an L bracket and then its legal

  4. #34
    Join Date
    Apr 2010
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    Houston, Texas area
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    For my stationary tool locations I put round floor boxes in my concrete floor without any receptacles. The machines are direct wired. They are probably never going to be moved or unplugged, and if they need to be unplugged it only takes a minute to remove a few wire nuts.

    By my workbench I have a couple of receptacles in the floor that I rarely use, I'm too lazy to bend over when there are high receptacles on the back bench 6 feet away.

    If you are worried about dust in unused receptacles consider putting in an outlet plug.
    Mark McFarlane

  5. #35
    Thanks, Mark. I have always had my tools on wheels and have needed them to be mobile to line up temporarily with doors for long stock or to get the tool out of the way to use the floor space. But this is a bigger shop than I have had before. Maybe if the tools find a comfortable place to rest where they do not have to be moved, I will do as you have.

    TW

  6. #36
    Join Date
    Apr 2017
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    Michigan
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    2,758
    Since you have a basement you can mount outlets in the basement ceiling. Then make a hole and drop the cord thru it, go downstairs and plug it in.

  7. #37
    Join Date
    Mar 2003
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    SE PA - Central Bucks County
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    65,688
    Quote Originally Posted by Tom Bender View Post
    Since you have a basement you can mount outlets in the basement ceiling. Then make a hole and drop the cord thru it, go downstairs and plug it in.
    Yes, that "will work", but it's not kosher, AFAIK.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  8. #38
    Join Date
    Apr 2010
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    Houston, Texas area
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    Quote Originally Posted by Jim Becker View Post
    Yes, that "will work", but it's not kosher, AFAIK.
    i.e., any electrical wire that goes through a floor/ceiling/wall penetration needs to be rated for that particular kind of installation.

    Extension cords in a wall (or thick floor ceiling assembly) are a no-no. An extension cord run inside a floor/wall doesn't dissipate heat as well as one in open air. The selection of the insulating material used in an extension cord is based on being used only in open air.

    Inside a wall (or floor or any other contained or semi contained space) the wire can't dissipate heat as quickly as in open air, increasing the chance that the insulation melts and you get an electrical short.

    Apparently a lot of homes burn down every year from people pulling extension cords through the wall to feed a wall-hung tv.
    Mark McFarlane

  9. #39
    Join Date
    Apr 2017
    Location
    Michigan
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    Good point, be sure to oversize the cord and don't run it in the wall or floor, just thru the floor and in open air to the outlet. I would feel safer with this than a flush in the floor outlet.

  10. #40
    This was my solution - basement shop so couldn't come up from under the floor. built around support pole and ran to electrical box - planning for a 3 hp 220 saw in future.IMG_0745.jpgIMG_0744.jpg
    Last edited by Brad Friesen; 05-04-2019 at 9:48 AM.

  11. #41
    Back when I had a basement shop, I also attached my mid floor outlets to the metal column. I used surface-mounted conduit and shallow metal handiboxes. Functional but not attractive. I like your solution.

  12. #42
    Join Date
    May 2014
    Location
    Alberta
    Posts
    2,162
    When I built my shop I ran two conduits to locations where I knew my jointer and planer were going to be and my tablesaw/saws. After I poured my concrete floor ,and I talked to my electrician we did indeed install two steel RV pedestals. I have a double 110V outlet on one side and wiring for the machines coming out the other side. Since I have bought and sold several machines since The first set up it has come in handy to switch stuff around. I really like the pedestals in the middle for extension cords,I use a 15' cord so way less laying around to trip on.

  13. #43
    Join Date
    Mar 2019
    Location
    Los Angeles, California
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    961
    Here, the building inspectors would give you a really hard time with floor outlets, which generally have to be at least 15 inches from the floor to the top of the box. There are exceptions and the box is raised slightly with a tight fitting brass cover. Plastic is allowed here, and is especially desirable considering the cost of such covers in brass, about $40.

  14. #44
    Quote Originally Posted by Tom Bender View Post
    Good point, be sure to oversize the cord and don't run it in the wall or floor, just thru the floor and in open air to the outlet. I would feel safer with this than a flush in the floor outlet.
    You cannot pass a cord through any opening of the building finish, the cord, plug, receptacle must be in the same room.

  15. #45
    I awoke this morning in Atlanta with not much on the agenda. I have a long simmering project in the Neanderthal shop or I have some photos of installing electrical floor boxes at the shop that I could turn into a post for the Sawmill Creek community. The deciding factor is on our last trip to Atlanta, the shop was converted into an art studio for the granddaughter and the painting is not quite finished.


    She may come over to play this afternoon (soccer game was cancelled). I thought I would leave things as she left them.
    Attachment 476116

    Instead, I am resurrecting an old thread in which I asked for the collective wisdom of the group about electrical floor outlets in the shop. I appreciated the education and after a long delay, I am finally installing them. This post is to report on what I used, how I installed them, and the problems encountered. First, the boxes. I bought boxes designed for installation in a wood floor. Apparently, boxes installed in concrete in an office cube farm are more common. Boxes for concrete are plastic with molded fittings for plastic conduit and not designed to be hung from a ledge in the wood floor using Romex. I spent several days searching. I first found Hubbell brand boxes online but they where phenomenally expensive, more than $400 per box and are just not available for order anywhere. Then, I found another high quality but still expensive brand, Legrand, at about half as much as Hubbell. The company must have changed hands several times in recent years as I found the same boxes listed as Wiremold, Walker, and Legrand. They are sturdy and nice looking. The system consists of four parts: metal electrical box, receptacle, flange and cover plate. The flange and cover plate are heavy cast, solid brass and look very nice.
    Attachment 476117

    The box has ears that are recessed into floor that support box. The flange is a standard component for all cover plate. The cover plate fits within the flange and can be selected for duplex, rectangular, 220v 20 amp, various communications plugins, etc. I got three rectangular (Decora-stye) GFCi 20 amp, 110 V and three twist-lock, 20 amp 220v receptacles. I ordered these quite some time ago at least 10 weeks. The last items on the order, coverplates for the 20 amp 220v receptacles, have still not arrived. I went ahead and cut the holes for the boxes which is sort of a woodworking project.





    As in most things at the shop, I had never done this before and apparently no one on Youtube has either. I was left on my own to make up a procedure. I wanted the recess for the flange to be snug and the hole in the boxes to allow for adjustment without reducing width of the lip for supporting the box too much. I made several practice holes in plywood to check the fit. A 1/32 gap around the flange was too much, so was 1/64. On third try I went for exact fit and tapped the flange into place for a snug fit. The ledge for the ears and the hole for the box were sized for 1/16 clearance. That seemed to work without having to adjust any holes.

    I wanted to use routers and guide bushings with templates to make the hole for the box and the recesses for the flange and ears. The templates themselves are also cut with router inside a four-sided outline made up of track saw tracks and crosspieces that are screwed down. The base of the router is the guide bushing for cutting the template. I cut cross pieces to precise lengths to set the dimensions for cutting the templates. To set the spacing between the side pieces, I used two spacers that were removed for cutting the hole. This is one of very few times I wished for a CNC router to cut the holes. After several holes, I had a system of marking templates but it was slow.

    TemplateCutGuide.jpg

    It is always a good idea to test templates all the way from start to finish. I made a practice hole in plywood, actually several as I tuned the fit. The first try I discovered that the installation instructions were a bit off. The recess specified in the instructions was too shallow and farced the flange retention screws to stick up too high for the cover plate to screw down flush. All that was necessary was to cut the recess for the ears 1/8” deeper.
    TestHole1.jpg
    The offending screw head.
    TestHole2.jpg
    The finished test hole looks pretty good.
    TestHole3.jpgTestHole4.jpg

    After cutting the box hole, I needed a way to locate the templates for flange and ears centered exactly over the box hole. I made a two-piece alignment plug for each template. The bottom piece fits precisely in the box hole and the top piece is sized to fit within the template.

    PlugInHole.jpg



    More to come. This post has hit the picture limit.

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