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#198996 - 02/09/11 08:52 PM conduit to suspended ceiling
triple Offline
Member

Registered: 04/01/02
Posts: 182
Loc: Wisconsin
Does emt piped directly to a box in a suspended ceiling tile violate the NEC? The tile will no longer be removable or replacable.

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#199001 - 02/09/11 11:28 PM Re: conduit to suspended ceiling [Re: triple]
gfretwell Offline

Member

Registered: 07/20/04
Posts: 9045
Loc: Estero,Fl,usa
How did you support the EMT within 3' of the box?
How is the box secured?
Answer those and it is probably legal.

I would start at 314.23(D) and work backward from there.

If the box was independently supported from the structure of the building it would make the decision easier. Then the ceiling is just "there" and not part of the equation.
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#199022 - 02/10/11 12:12 PM Re: conduit to suspended ceiling [Re: triple]
Tesla Offline
Member

Registered: 06/16/04
Posts: 1280
Loc: Sacramento, CA
Sounds VERY flaky.

It'd get shot down here.

If it's directly on the tile then it's unsupported by California standards.
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#199024 - 02/10/11 12:46 PM Re: conduit to suspended ceiling [Re: triple]
renosteinke Offline
Cat Servant
Member

Registered: 01/22/05
Posts: 5305
Loc: Blue Collar Country
It's not a bad question ...

Caddy and B-Line both make brackets that are designed to clip onto the grid and support a box anywhere in the tile. The 'customary' wiring method is for the last part of the conduit run to transition to flex or MC; then you can still move things if needed.

Yet, these days we're not supposed to 'support' anything from the grid. Light fixtures need their own support wires. Would this bracket also need to have wire supports too? Or, is the support of the conduit enough?

What if the ceiling tile has been replaced by a wood panel, and the box attached to it?

I fear we have pretty much made the suspended ceiling obsolete.

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#199035 - 02/10/11 09:24 PM Re: conduit to suspended ceiling [Re: renosteinke]
PAteenlectrician Offline
Member

Registered: 01/06/11
Posts: 69
Loc: Cressona, Pa, U.S.A. (Schuylki...
What if the ceiling shifts? shocked

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#199038 - 02/10/11 10:36 PM Re: conduit to suspended ceiling [Re: triple]
gfretwell Offline

Member

Registered: 07/20/04
Posts: 9045
Loc: Estero,Fl,usa
Reno, 314.23(D)(1) does make it sound like those caddy clips are legal if the box is smaller than 100 cu/in

Quote:
(D) Suspended Ceilings. An enclosure mounted to structural or supporting elements of a suspended ceiling shall be not more than 1650 cm3 (100 in.3) in size and shall be securely fastened in place in accordance with either (D)(1) or (D)(2).
(1) Framing Members. An enclosure shall be fastened to the framing members by mechanical means such as bolts, screws, or rivets, or by the use of clips or other securing means identified for use with the type of ceiling framing member(s) and enclosure(s) employed. The framing members shall be adequately supported and securely fastened to each other and to the building structure.


I still imagine most AHJs will want to see a supplemental support wire or two. You could do the EMT thing if it was supported by the building structure within 18" of the box.
I have seen smokes and alarm beacons or beepers in a 1900 box, hanging in the grid but they were on an MC whip.
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