Receptacles flush-mount in drop ceiling (non-dwelling)

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lordofpi

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Location
New Jersey
Hi all. I haven't posted in a while; I'm glad to see all the usual knowledgable posters are still alive and kicking!

I have a brief question regarding installing receptacles in a drop ceiling of a commerical building. I have about 7 boxes to put in, each containing two duplex receptacles, which will be flush mounted in standard 2'x4' ceiling tiles. All runs will be made in 1/2 EMT strapped to the joists above the suspended ceiling. What is the best way to install the boxes? I was thinking about using 1900 boxes suspended by all-thread hanging from Uni-strut mounted to the joists. My colleagues think this is overkill since I am using EMT; I could probably use tie-wire and hang them from the joists, but I know that EMT cannot be a means of securing a junction box. I'm sure some of you do this kind of job all the time; thoughts?
 

roger

Moderator
Staff member
Location
Fl
Occupation
Retired Electrician
Hi all. I haven't posted in a while; I'm glad to see all the usual knowledgable posters are still alive and kicking!

I have a brief question regarding installing receptacles in a drop ceiling of a commerical building. I have about 7 boxes to put in, each containing two duplex receptacles, which will be flush mounted in standard 2'x4' ceiling tiles. All runs will be made in 1/2 EMT strapped to the joists above the suspended ceiling. What is the best way to install the boxes? I was thinking about using 1900 boxes suspended by all-thread hanging from Uni-strut mounted to the joists. My colleagues think this is overkill since I am using EMT; I could probably use tie-wire and hang them from the joists, but I know that EMT cannot be a means of securing a junction box. I'm sure some of you do this kind of job all the time; thoughts?



I support them from the structure as you have described or by some similar method. I have found that the Caddy T Bar type hangers Jim mentions do not work well for receptacles, they do not hold the grid down very well when inserting a plug into a new commercial or spec grade receptacle.

Roger
 

lordofpi

Senior Member
Location
New Jersey
they do not hold the grid down very well when inserting a plug into a new commercial or spec grade receptacle.

Yes, this was one of my concerns. Plus, we all know how the tiles tend to crumble over time from any strain on them. But, as I said, I have never had to do this, so if others are in support, the T-Bars may just do the trick and much more quickly.
 

roger

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Location
Fl
Occupation
Retired Electrician
Greg, that still won't help the grid from lifting up.

Roger
 

dcspector

Senior Member
Location
Burke, Virginia
Greg, that still won't help the grid from lifting up.

Roger

Roger true I thought from the OP and maybe I misread the all thread that was supporting the 4sq supported off stut would have reduced push up so to speak. Also, I thought EMT was ran directly to the box.
 
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wawireguy

Senior Member
I'd probably put junction boxes in my EMT run and come off those with MC to the receptacles. I'd use t-bar hangers to support the boxes.

Something like that:
http://www.erico.com/products/CADDYcfcTGrid.asp

In a commercial application I wouldn't worry about the grid pushing up. They are going to plug in their equipment once or twice and leave it there.
 

lordofpi

Senior Member
Location
New Jersey
Roger true I thought from the OP and maybe I misread the all thread that was supporting the 4sq supported off stut would have reduced push up so to speak. Also, I thought EMT was ran directly to the box.

Hey Greg, hope all is well. Yes, I was debating whether to use a T-Bar or strut/all-thread -- not both (or maybe old-work boxes or Madison bars, but I don't think that would quite work in a fiberglass tile). I will be piping EMT from the joists above and 90-degree bend right into the 1900 receptacle boxes, which ought to give adequete stiffness as it is. As Wawireguy indicated, the cords will be plugged in once and pretty much left there. I guess my hesitation comes from knowing that fire code really looks down on things being supported by ceiling grid or tile, but an extra tie-wire around each box might allay that worry.
 

dcspector

Senior Member
Location
Burke, Virginia
Hey Greg, hope all is well. Yes, I was debating whether to use a T-Bar or strut/all-thread -- not both (or maybe old-work boxes or Madison bars, but I don't think that would quite work in a fiberglass tile). I will be piping EMT from the joists above and 90-degree bend right into the 1900 receptacle boxes, which ought to give adequete stiffness as it is. As Wawireguy indicated, the cords will be plugged in once and pretty much left there. I guess my hesitation comes from knowing that fire code really looks down on things being supported by ceiling grid or tile, but an extra tie-wire around each box might allay that worry.

All is well. As far as securing to grid is not in the IFC. It is a siesmic consideration. for luminaires and other equipment..We are a Category B (exempt) this is more of a 314.23(D)(1) thing. Looks like ya got it covered.
 

celtic

Senior Member
Location
NJ
I will be piping EMT from the joists above and 90-degree bend right into the 1900 receptacle boxes, which ought to give adequete stiffness as it is.

Personally, I would go with a rod/joist hanger to the deck above....the guys installing the outlets will really appreciate the box not moving all over the place while they jam pigtails and devices in the JB [I would also use a deep 1900 box for that "extra" cushion]...
 
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