How To - 220 Outlet in floor?
#11
My shop is a work in progress. When I ran the 4- 220 circuits I installed the outlets in the walls where I thought they would be needed. They are placed OK but the cords run across the floor and are a tripping hazard. Now that the machines have found there home I would like to put the 220 outlets below the floor. Has anyone done this? Pros and cons. I have a 4' crawl space so access is not a problem. My thoughts are, how to keep most of the saw dust out of them? My plugs are twist lock 3- L6-30 & L6-50. Another question can you put a junction box for 220 circuits in case the wire is not long enough?
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#12
You'll want to use an outside type sealed box with a hinged lid. Make the lid mount so it is flush with the floor.
Mine are in concrete, which was easy to do.
Steve

Missouri






 
The Revos apparently are designed to clamp railroad ties and pull together horrifically prepared joints
WaterlooMark 02/9/2020








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#13
(02-18-2019, 06:33 PM)lift mechanic Wrote: I would like to put the 220 outlets below the floor. Has anyone done this? Pros and cons. I have a 4' crawl space so access is not a problem. My thoughts are, how to keep most of the saw dust out of them? My plugs are twist lock 3- L6-30 & L6-50.
Our middle school shop, originally our high school built in 1930's, had wooden floors and the outlets were below the floor.  They had these bronze, brass maybe, boxes... or maybe just patina. Anyway, they had doors that slid off,  (edit: as stwood suggested, these doors were more lid like and were flush with the floor) the outlets were recessed down and under the floor boards. Then the doors slid back and the cords were directed through via a small circular brush cutout.  Dust was in there, but no wood chips or sawdust.

Another question can you put a junction box for 220 circuits in case the wire is not long enough?
I believe so, as long as it accessible.  When I had my service panel moved, the electrician installed a box and pig-tailed a lot of circuits. But some circuits, my 240v dryer circuit among them, he installed separate junction boxes as it was closer to the new panel than routing from the old.

P.S. What  i am suggesting is to add some boxes to the floor joists, drill a small hole through the floor about an inch infront of the receptacle to mark the location, take a multi-tool and-using a 2x4 cut at 45° as a guide- cut a beveled access panel to the outlet.  The door will slide about a 1/16" from level.  Cut a u-shaped hole big enough for your cord.
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#14
I've installed floor outlets, but for 15/20 amp receptacles. Looks like this:

[Image: Z0-vsufo5oy.JPG]

Don't know if they have the equivalent for higher current outlets, but it would surprise me if they didn't.
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#15
(02-18-2019, 06:33 PM)lift mechanic Wrote: Now that the machines have found there home I would like to put the 220 outlets below the floor. Has anyone done this? Pros and cons. I have a 4' crawl space so access is not a problem. My thoughts are, how to keep most of the saw dust out of them? My plugs are twist lock 3- L6-30 & L6-50.

Most of the time, I see a short post with a disconnect and hardwired machine, though a plug/receptacle combo qualifies as a disconnect (to satisfy the NEC).  Consider a marine receptacle, which has a hinged lid, as already mentioned.  I'm not aware of any pop-up boxes or fixed curb types for receptacles larger than 15/20A simplex or duplex.  But if the machine won't be moved normally, I'd just put a short post and conduit to a surface box with appropriate receptacle.  

(02-18-2019, 06:33 PM)lift mechanic Wrote: Another question can you put a junction box for 220 circuits in case the wire is not long enough?

Nothing in the NEC prohibits using a junction box on 240V circuits, which are fundamentally the same as 120V circuits anyway, being that voltage to ground on either leg (in North America) is 120V.  Heck, I have five junction boxes on the six 240V receptacles on one 20A circuit sprinkled around my shop, just like the 120V circuit running around the walls of my shop.
Tom

“This place smells like that odd combination of flop sweat, hopelessness, aaaand feet"
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#16
(02-18-2019, 06:33 PM)lift mechanic Wrote: My shop is a work in progress. When I ran the 4- 220 circuits I installed the outlets in the walls where I thought they would be needed. They are placed OK but the cords run across the floor and are a tripping hazard. Now that the machines have found there home I would like to put the 220 outlets below the floor. Has anyone done this? Pros and cons. I have a 4' crawl space so access is not a problem. My thoughts are, how to keep most of the saw dust out of them? My plugs are twist lock 3- L6-30 & L6-50. Another question can you put a junction box for 220 circuits in case the wire is not long enough?

I ran conduit under the concrete slab to the center table saw location in my shop.  At the stub up I screwed a 4x4 metal box to the concrete.  On top of that box I placed a double sided floor stanchion.   On one side is the 220 for the tablesaw and on the other is the 110 for the other island tools.   The bottom box raised the stanchion up 2" so I don't have to worry about water getting into the box.  Since it's under the tablesaw island location I don't worry about tripping over it.  I painted the bottom box red which you can see in this photo.

[Image: unisaw.jpg]
WoodNET... the new safespace
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#17
Here is a link to some Hubbell tear sheets on floor receptacles and cover plates: seem to go up to 30 amps.

Hubbell
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#18
Thanks for all the replies.

Maybe I have been over thinking this. Would it be OK if I drilled a hole in the floor at the machine and just below the outlet. Just larger than the cord. Removed the plug and run the cord under the floor, support the cord at least every 48". Then put the plug back on. I think the cords are SO type and there is plenty of length. Yes it would be a pain if the machine had to be moved, but they have not moved in 2 years.
Treat others as you want to be treated.

“You only live once, but if you do it right, once is enough.” — Mae West.
24- year cancer survivor
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#19
(02-21-2019, 10:51 AM)lift mechanic Wrote: Thanks for all the replies.

Maybe I have been over thinking this. Would it be OK if I drilled a hole in the floor at the machine and just below the outlet. Just larger than the cord. Removed the plug and run the cord under the floor, support the cord at least every 48". Then put the plug back on. I think the cords are SO type and there is plenty of length. Yes it would be a pain if the machine had to be moved, but they have not moved in 2 years.

I think you should have a way to unplug the machine before it enters the floor... or install a disconnect.  Maybe an extension cord would solve your needs.  I have 220 extension cords on a few of my machines to make them more mobile.
WoodNET... the new safespace
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#20
Yes. You need to disconnect the saw before any blade changes.
Unplug....
Shut off circuit breaker....

I always do one or the other. Usually shut the circuit breaker off.
Steve

Missouri






 
The Revos apparently are designed to clamp railroad ties and pull together horrifically prepared joints
WaterlooMark 02/9/2020








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