Floor boxes

Status
Not open for further replies.
C

chevyx92

Senior Member
Location
VA BCH, VA
I have a job starting soon that will have 70 floor boxes in the slab. Most are just power and a few with power and data. I know I will need a divided box for the power/data boxes. Any good ideas to keep all these boxes in place once set so they won't move? Also any recommended boxes to use? Thanks.
 
Who is specifying the boxes? Floor boxes range from cheap to ultra expensive and come with all sorts of flange options from plastic to brass.

For existing floors, after chopping, we usually concrete them in place leaving the mix about 1.5" below the top of the box so the mason can smoothly finish the floor. Installations in new concrete pours are an entirely different animal.

Can you possibly use poke thru's?
 
i generally just bend a keyway stake in half and hammer it into the dirt to hold my boxes. i put the keyway stake on the pipe feeding the box about 3" off the box coupling and continue down about every 10' until i reach the point where the pipe leaves the slab.
 
its a flat metal stake about 16" long and is used to secure the keyway in the slab. it has a notch on the end that attaches to the keyway and you hammer it into the dirt. i bend them in half over my knee and put it over my pipe.
 
chevyx92 said:
I have a job starting soon that will have 70 floor boxes in the slab. Most are just power and a few with power and data. I know I will need a divided box for the power/data boxes. Any good ideas to keep all these boxes in place once set so they won't move? Also any recommended boxes to use? Thanks.
Click to expand...

What are you mounting to? What type of slab? (On grade - in forms - deck?) Either way - gaining the respect of the guys pouring the concrete is probably the best thing to do first.... That goes a long way. (i.e. don't walk on their forms, etc.) But also good to find out the FULL picture of where shut-offs and drain grades are going to REALLY be. As there is nothing like coming back to dig out your boxes, or worse seeing the hump they troweled up to your box if too high. Makes everyone look bad....

Otherwise, I usually use RMC to enter/exit the boxes, and tie-wire it to death, that keeps the lateral movement to a min. - But also works well with PVC too. The problem always seems to be the horizontal, from either the rebar grid sagging, or being walked on, etc. For that I do my best to prop the box up to the finish on either scrap conduit, rebar or on a few occasions threaded rod. If on grade a 12" sq piece of ply so whatever you prop it up with doesn't sink into the ground. And of course, more tie wire so that doesn't float off in the pour. But better yet, if depth allows use the conduit to hold it, and come up into the bottom of the boxes...

On the box spec.... You had better check that with an RFI - pretty big range there....
 
Finish Floored

Finish Floored

For goodness sakes read the floor finish schedule, if it gets into wood be up front that your cover plate is tops 2" out if that from edge of box, saw a big job go south where they had to order custom covers to pick-up the floor man, plus bad vibes, etc ...
 
cadpoint said:
For goodness sakes read the floor finish schedule, if it gets into wood be up front that your cover plate is tops 2" out if that from edge of box, saw a big job go south where they had to order custom covers to pick-up the floor man, plus bad vibes, etc ...
Click to expand...
Yeah, you really can't count on the GC to do allthe 5-trade coodination...
 
floor boxes

floor boxes

we have put box outs where the floor boxes go. make sure the conduits are at the right angles. thats alot of floor boxes though. stake em up tight and Put a guy in with the pour to make sure they stay the way you want them. if you have a spare guy.
 
phishwi said:
we have put box outs where the floor boxes go. make sure the conduits are at the right angles. thats alot of floor boxes though. stake em up tight and Put a guy in with the pour to make sure they stay the way you want them. if you have a spare guy.
Click to expand...


For that number of boxes, that is a good idea.
The concrete guys can be a little rough... like stepping all over those boxes, sometimes pushing them down and then covering them with concrete.
 
Pierre C Belarge said:
For that number of boxes, that is a good idea.
The concrete guys can be a little rough... like stepping all over those boxes, sometimes pushing them down and then covering them with concrete.
Click to expand...


i found that out the hard way. with a hammer, chisle, and a hilty. after they buried our boxes the truck ran over our walker duct. never again
 
phishwi said:
~Put a guy in with the pour to make sure they stay the way you want them. if you have a spare guy.
Click to expand...

Isn't that what happened to Jimmy Hoffa? Not a bad idea though.... To have a guy 'around' - maybe not IN the pour... ;)
 
Pierre C Belarge said:
The concrete guys can be a little rough... like stepping all over those boxes, sometimes pushing them down and then covering them with concrete.
Click to expand...

Sounds like 'pay-back' - Thats why I mentioned gaining their respect.... I dragged one of my guys off a job years ago before the concrete crew ripped him a new one for walking on the forms - messed up two days work for them without realizing it before all hell broke loose on him when he was caught... From that point all 'electricians' were mud in their eyes. They only see you as some sort of trespasser in their domain - knowing more about their trade and lingo can solve a lot IMO.
 
A good way to check all of your box heights is to use a temporary screed line. Doing it this way will save a bunch of head scratching, and give you a good idea of what the finished slab is going to be like. Ask them for the datum and at what level they are going to screed from and where if any points they are going to change level - especially at the drains... (Only using a drain as an an example of where a floor might change level... But some slope to plumbing clean-outs ect.) Often one of the last things they do before they pour is to instal a "Screed wire" to any drains/clean-out so they can get the slope from point to point. Usually from the top of forms and cut-offs, or joints then to the drains. (If any) Otherwise they often just go screeding across with a 2x4 and a level point to point.

A job with that many floor outlets, if you get them all solid and in the right place they can screed to the boxes.... At which point they will take very good care of them....

This would be much easier to explain in a 3d drawing but I attached one in 2d.

For 3d download the "free version" of Sketch-up, then open this file.
 
Last edited:
Status
Not open for further replies.
Top