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Re: Floor Boxes

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Not very helpful, but yes it is standard practice to provide a floor system capable of accommodating the floor boxes, particularly for open area office spaces.  On some projects we have had to accommodate electrical raceways (walker ducts), in fact this is common enough that some metal deck manufacturers produce decking with integral raceway systems. 
 
Since it sounds like the steel joists are on site as well as the decking, the sump pan and deck reinforcement would be an option worth exploring.  2" plain concrete can span 24", so the reinforcement requirements should be fairly reasonable.  The floor box you reference is available in a 2.5" depth model, is it possible the shallower box will work with an additional .0625" of concrete?
 
Look on the bright side, at least the concrete wasn't placed with all the boxes protruding an inch out of the slab :-)
 
----- Original Message -----
From: Mike Zaitz
Sent: Tuesday, January 28, 2003 2:34 PM
Subject: Floor Boxes

Hello;
 
Looking into a problem that has appeared.  I have a concrete slab on 9/16" form deck (3" total thickness) on bar joists at 24" o.c.  The Electrical Engineer has informed me that he is required to use floor boxes (http://www.fsrinc.com/ see model FL-500P) for electrical.  These boxes are approximately 12"x10" in plan and 4" deep.  The support steel is already designed and I am trying to find a cost effective solution for these boxes that will now penetrate my floor without adding a large amount of weight (aka increasing slab thickness).  Fire protection is not an issue per the architect.  An idea that has been tossed around is to use a typical 14 ga sump pan that will be used as a form and reinforce it with rebar.  I do not see how this issue has not come up but all my searching has been for naught.  Is typical practice to increase the thickness of the slab for floor boxes?
 
Mike