What's a box-out for floor boxes?
- Thread starter schicco
- Start date
- Status
- Location
- Tennessee NEC:2017
- Occupation
- Semi-Retired Electrician
I don't understand your question?
Little Bill
I am reading a spec; we are supposed to install floor data & power outlets. To run conduits via ceiling of floor below. To provide dimensions of "box-outs" for steel floor boxes before concrete pour. I am lost on the "box-out" part. Could it be a crude way of saying dimensions of boxes?
Thanks
Steve
I am reading a spec; we are supposed to install floor data & power outlets. To run conduits via ceiling of floor below. To provide dimensions of "box-outs" for steel floor boxes before concrete pour. I am lost on the "box-out" part. Could it be a crude way of saying dimensions of boxes?
Thanks
Steve
- Location
- New Jersey
- Occupation
- Journeyman Electrician
You literally put a wooden box (say 2'X2') or some other material (we have used layers of Styrofoam) on the deck before the concrete is poured. The box-out is removed and electrical box is installed after the concrete is poured and the box-out is patched with the box in it. This allows for the box to be set to the proper height and exact dimensions after the deck is poured. We once did a job where they wanted the floor boxes centered on the intersection of 4 tiles, we installed the box-outs prior to the pour and then the tile guy layed out his seams on the concrete and we set the boxes from there.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
We did a concrete floor that had 32 floor boxes. We couldn't box it out so the boxes had to go in first. Of course, they wanted the rectangular boxes not the round ones. What a nightmare but we got it. They did not want patched in the floor that had color added to it
- Location
- New Jersey
- Occupation
- Journeyman Electrician
All depends on what the designer wants. Poke throughs are limited in size when compared to some large floor boxes.
i guess I always thought that a big box in the middle of an elevated floor slab would weaken the slab. But I guess the structural designer deals with it. Maybe they run rebar around the cutouts?
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Yes typically there is extra rebar if the penetration is very large. We often have penetrations for conduit runs that can 15-20 square feet, the lather usually reinforces the area with extra rebar under the direction of the structural engineer.
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