T-bar ceiling box with EMT conduit

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billclou

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I am about to start a fire alarm conduit job and the majority of the devices will be ceiling mounted on an existing suspended (T-bar) ceiling. I want to use an EMT conduit system for this project. Without getting into the requirements of the actual box support, something in the back of my mind is telling me that the conduit between the fixed building structure and the flush boxes in the ceiling shall be flexible. I can't find this requirement anywhere in the code. Am I wrong?? Any ideas?? The job is in Southern California.
 
... I want to use an EMT conduit system for this project. Without getting into the requirements of the actual box support, something in the back of my mind is telling me that the conduit between the fixed building structure and the flush boxes in the ceiling shall be flexible.

If you were to use EMT conduit to the devices mounted in ceiling tiles, it sure would be hard to replace the ceiling tiles IMHO. Is conduit required for your Fire Alarm wiring ?
 
If you were to use EMT conduit to the devices mounted in ceiling tiles, it sure would be hard to replace the ceiling tiles IMHO. Is conduit required for your Fire Alarm wiring ?

If you put the box edge by the lip of the t-tab you can do it rather easily. If the box is not at an edge, you have to split the tile.

I suggest going for the edge.
 
I don't know of any NEC code that says you need a flexible connection between structures and a cieling tile mounted device. It's usually easier and faster to install something flexible, IMO. Caddy has a whole host of products for mounting EMT and boxes to cieling grid.
 
If you put the box edge by the lip of the t-tab you can do it rather easily. If the box is not at an edge, you have to split the tile.

I suggest going for the edge.

While that may work, a round smoke detector would look kinda silly if not centered in the tile. Thanks though....
 
Why not run boxes overhead with a piece of flex down to the box in the t-bar? Sure it may add a bit of material cost but I see it saving a bit of labor.

I agree, however Simplex would have trouble with this design as they are pulling the wire. Thanks
 
I don't know of any NEC code that says you need a flexible connection between structures and a cieling tile mounted device. It's usually easier and faster to install something flexible, IMO. Caddy has a whole host of products for mounting EMT and boxes to cieling grid.

This in a nutshell is where I am questioning myself. I don't think that it is a requirement of NFPA 70, just good standard workmanship. What I'm trying to find is what the actual codes are, and if there are any other requirements (building codes) that are specific. The more I think about it, the more I'm leaning towards a flexible connection. I'll have a heart to heart with the alarm construction manager in a few. Thanks for the input.
 
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