PDA

View Full Version : Outlets in the middle of a concrete floor



Roger Warford
02-28-2008, 2:17 PM
I am in the process of setting up my first shop (http://www.sawmillcreek.org/showthread.php?t=77966). I will need to run outlets out into the middle of the floor (a 220V for the TS, a couple of 110V/20A for other equipment). I plan on running thick wall conduit under the DC ductwork (which will only be a few inches above the floor), then bend the conduit up to make a short stand (6" to 12" tall) on which I will mount an enclosed outlet box. I am thinking this will be better than laying them on the floor where they will collect dust and possibly worse (screws or nails!).

Can anybody share some experiences with similar setups? Is this a reasonable approach (or even up to code)?

WAIVER OF RESPONSIBILITY:
I hereby waive my right to sue, insult, harass, or generally annoy any and all respondents providing unlicensed advice and/or recommendations related to said wiring. Should I fry myself - it's my own durn fault! :)

Von Bickley
02-28-2008, 3:17 PM
Roger,

That's close to what I have in my shop. I don't have 220 pulled there, but I have it available to the conduit.

I ran my conduit so it comes up beside my out-feed table. It provides power to the tablesaw and to outlets on both sides of my out-feed table. Works great for me. :)

Greg Funk
02-28-2008, 3:24 PM
I used these floor plugs in a few places and they work well for me. I was warned about dust in the flush mounted plugs.

Greg

Rob Russell
02-28-2008, 3:41 PM
I plan on running thick wall conduit under the DC ductwork (which will only be a few inches above the floor), then bend the conduit up to make a short stand (6" to 12" tall) on which I will mount an enclosed outlet box.

I question whether that's a code-compliant installation. Generally speaking, boxes have to be supported by something other than the conduit.

You could bolt something to the floor and mount the box on that. It would also give you something to secure the conduit to. Unistrut would work well for that purpose.

Rob
Addy protocol: unlicensed, homeowner electrician

Roger Warford
02-28-2008, 11:13 PM
Thanks to all for the feedback. Really good point Rob - I'll put together a small frame to support the boxes. Seems obvious now that you've pointed it out. I'll also browse the NEC online for relevent issues thanks to a link posted in another thread.

Don Abele
02-28-2008, 11:26 PM
I question whether that's a code-compliant installation. Generally speaking, boxes have to be supported by something other than the conduit. You could bolt something to the floor and mount the box on that. It would also give you something to secure the conduit to. Unistrut would work well for that purpose. Rob

Rob, I don't have the NEC but just recently picked up a book on wiring which gives tons of examples and quotes NEC articles. As soon as I read your response I remembered something I just read in it and went back to the book where it talks about installing an outdoor outlet for a swimming pool. It says that per NEC 314.23(F) the box must be supported by at least TWO conduits. Can you look that up and verify it for Roger? Hopefully that can clarify the requirement.

Be well,

Doc

Roger Warford
02-29-2008, 12:34 AM
Thanks Don. I found the section you were referring to online (http://www.nfpa.org/freecodes/free_access_document.asp?id=7008SB) (the thread that included this link can be found here (http://www.sawmillcreek.org/showthread.php?p=755688#poststop)). Section 314.23(F) is titled "Raceway-Supported Enclosures, with Devices, Luminaires, or Lampholders". If I read it correctly, I don't think it applies. But it seems interesting that this exception is available for devices (luminaires) weighing up to 20lbs(!), but an simple outlet isn't allowed (as best I can tell). Oh well. It shouldn't be too difficult to build a simple frame. Not sure how to anchor it into cement though. Drill a hole with an impact drill and use a cement anchor? Back to google I guess! :)

Rob Russell
02-29-2008, 6:49 AM
Thanks for putting that up (the code cite).

I was obviously wrong. It's good to learn new things.

Personally, I think I'd want a frame anyway, just because it'd be stiffer than the conduit. Having said that, it's obviously OK to have the conduit supporting the box - and as the exception notes - you can do it with a single conduit provided you follow the rules in the exception.

Rob Russell
02-29-2008, 7:32 AM
If I read it correctly, I don't think it applies.

Why not? When I read the section, it looked like it would apply to me. There are restrictions on the kind of conduit you use, but it sounds doable.

It still might be easier to build a little frame and run regular conduit. In terms of how to attach the frame to the floor, a concrete bit in a hammer drill and tapcons or drill a larger hole and use lead lag shields and lag bolts.

Jon Crowley
02-29-2008, 8:51 AM
Not sure how to anchor it into cement though. Drill a hole with an impact drill and use a cement anchor? Back to google I guess! :)

Simple pressure treated 2x4, make some pocket holes, then tapcon into the concrete. :rolleyes::D

Walt Nicholson
02-29-2008, 10:04 AM
If you are going to have to have this inspected for code as part of the wiring inspection of the new building make sure you check local codes. I was going to do the same thing in my new shop and found that since I had a garage door in the building (which would allow vehicles, RVs, etc. into the building) all electrical outlets had to be a minimum of 46" above the floor. It did not matter that the only reason for the door was to help bring things in and out of the workshop and that I have way too much "stuff" in the shop to have any vehicle in there, the garage door was the kicker. Something about propane, gasoline fumes, etc. settling to the floor and possible electrical sparks causing "the big bang". If you are doing the wiring yourself and not pulling a permit it is a non-issue and maybe the folks around here are just weird in their restrictions. Just an fyi. ;)

Roger Warford
02-29-2008, 11:17 AM
Thanks. I have an impact drill and should be able to get some Tapcon at the local borg. I'll call my local inspector today (they are only available from 3:30pm to 4:30pm!) and check with them before I get started. I'm trying to do this the "right" way and get it approved.

Rob, I was assuming the code only applied to situations where light fixtures where being supported (such as exterior lighting). Do you read it differently? I was a bit bleary eyed when I read it, I'll have to read it again.

Jim Kirkpatrick
02-29-2008, 12:04 PM
I'm confused, Are you burying this conduit on concrete or laying on top? Or is it a wood floor? Make sure you use PVC and not EMT if you are burying in concrete. Someone else made a good point no lower than 48" in garage area. If there is a garage door in vicinity, you can always cover with an upside down bucket during inspection.

Jesse Cloud
02-29-2008, 12:09 PM
I had a similar experience to Walt's. Not code compliant here.

On top of that, we had a small water problem one day that would have poured right into a flush plug.

Roger Warford
02-29-2008, 1:01 PM
Jim, it'll be on top of an existing basement floor. No garage door, but I like the bucket idea!:)

Jim Kirkpatrick
02-29-2008, 1:42 PM
Jim, it'll be on top of an existing basement floor. No garage door, but I like the bucket idea!:)

Roger, I don't like the sound of conduit laying on top of the floor. Not only could you trip over it but it'll be a great place for dust to collect. What's wrong with overhead wiring with drop downs?

Roger Warford
02-29-2008, 2:32 PM
It's a good question Jim. My thinking (though I don't claim it's good thinking!) was that drops from the ceiling would potentially get in the way as I swing lumber around. The port on the Jet single stage DC I have on the way is near the ground. So I thought I would run the DC ductwork (or PVC) near the ground at the level of the DC port, avoiding one bend. Under that I would run the conduit. I would arrange my tools around that blocking the path so I won't accidentally trip over the ductwork or conduit (see my post here (http://www.sawmillcreek.org/showthread.php?t=77966) that shows the layout I am planning).

Rob Russell
02-29-2008, 3:02 PM
I relooked at your shop layout. It appears to me as if the pipe to jointer is right where you'd be walking everytime you finished jointing a board.

Is that correct?

Jim Kirkpatrick
02-29-2008, 7:46 PM
I was flipping a house a couple of years ago and had a Delta contractors saw rigged up in basement. I wired some plugs near lally columns that worked great. If you dont have any columns, I think if you keep the drops near the tools, you'll be all set. My .02 would be to keep them overhead. You'll be thinking of me every time you have to shop vac the dust around the emt and DC duct!

Fred Sotcher
03-01-2008, 9:13 PM
The floor receptacles are a great idea, I did the same thing in my shop. I might go a few steps further. I recommend that you pull wiring for both a 120 and a 240volt circuit. Things change and you might find the second voltage useful. You don't need to connect the wires at the lead, until you need them, but they are there if you do. Two other ideas. Along with the electrical conduit, run a 1/2 copper pipe for shop air. I also placed a 4 inch drain line that connects to my dust collector system. All this is easy to do at this point a very hard later.

Fred Sotcher

Roger Warford
03-01-2008, 10:44 PM
Rob, you are right, it's a bit tight in there. I spent the day cleaning out the space and setting up some equipment - I think I'll be able to push the pipe and wiring back a foot or two hopefully creating enough space to work. I marked off the area and made a few test runs today on the jointer and it seemed to go okay.

Jim, there are no columns in the space. Did you find the columns got in your way?

Scott, good suggestions. I do plan on adding two 120V/20A outlets as well.

EDIT: Forgot to add that I spoke with a local inspector yesterday. He has very helpful and a fellow WW! He confirmed that the box would have to be supported by something other than the conduit.

Samuel Brooks
03-02-2008, 1:17 PM
I went with ceiling mounted see attached pics. Mine setup is 120V but it could be 220V just as easy. I put in a standard 20A outlook then put in a large hook into the truss and used a zip-tie to hook the power cord so that it would not get pulled out by accident. I looked into Conduit but then I had to attach it to something and the inspector recommended that I get a locking plug .. $$$. When I showed him what I had come up with he though it was great and covered all code issues. I then added the 2nd drop down to run to my cut down table. After doing a project of moving between cut down with my easy-smart then going to the table saw for finish work, I got tired of switching my cables back and forth so I just added a 2nd hook and a 2nd cable. As you can see I was able to loop it out of the way when not in use. Since I have hanging ceiling fixtures I have to watch where I swing boards anyways so to hang it from the ceiling was not a big deal. Now I really like having power where I need it.

I am just waiting on an order from Penn State for Dust Collection transition connectors then I will also have a 6" run coming down from the ceiling at the same spot. I am really tired of walking over the 4" flex on the floor now. And if I do not leave it hooked up then I do not want to take the time to connect it for one use:mad:. It's just one cut .... 10 minutes later and 4 others that I realized that I also wanted to do before I changed the setup. :D.

Good Luck

Sam

83084
83085

John Browne
03-02-2008, 6:41 PM
Frankly I wouldn't want anything on the floor to trip over or block machinery if I wanted to move it around. I'd rather drop a post part way down from the ceiling and put outlets on it--my shop has a 2nd floor above so there are 3 6x6 posts running down the middle--PITA for things like table saws or big assy tables but handy for mounting outlets--I put a 220 and 120 circuit on each of two of them. You could also do a drop on a cord reel from the ceiling.