Rigidly and securely fastened

[ron]

Smoke detector installed above a suspended ceiling on the underside of the concrete slab above (approx 8' cavity) in corridors. To save $$$, the EC wants to mount the smoke detector on a 4"x4" box and attach the 4x4 box to a stick of 3/4" EMT which is bent such that it looks like a flag pole. The bend is placed so that when the vertical portion is held against the side wall above the suspended ceiling, the detector is located in the center of the corridor and against the underside of the concrete slab above. The bottom of the flag pole gets attached to the gyp board side wall above the suspended ceiling with two Minerallacs installed approx 6" apart beginning at the bottom of the "flagpole". Other than the two Minerallacs, the assembly is unsupported for the remainder of the vertical portion and the horizontal portion. The wire for the detector is wire tied to the side of the 3/4" conduit and enters the box through a grommet. The wire is not in the conduit so I can't say that the raceway is not supported per 358 because it is not raceway.
I think that the box support is not in compliance with 314.23(A) as the box it is not rigidly and securely fastened. The EC feels that he is in compliance with that article as he is following 314.23(B) and it does not require rigidly and securely, just rigidly. What does rigidly mean?
I am looking for opinions.
I think this is just a cheapie way of installing the device. The EC feels that he will save time, as he does not have to struggle above the deep cavity of the suspended ceiling and just raise the "flagpole" and attach to the wall near the susp ceiling elevation.

 

[dcl34769]

Re: Rigidly and securely fastened

IMO the EC is cheating the code. The 4x4 box is still supporting a device and should be properly secured to the concrete ceiling. If it were a light fixture would he do the same? Also,I do not belive that UL listed emt connectors for the purpose of box support. That would be a good argument against his install. Also, two mineralac straps spread 6" appart dose not sound like adequate support for anything to me, and a raceway is a raceway even if it has no wire in it. Tell him to buck up and do the job RIGHT.

 

[hurk27]

Re: Rigidly and securely fastened

Ron what type of detectors are these power limited, low voltage monitored alarm system, or just line voltage with inter-connect's?
There might be some other codes that are being violated as well. As type of cable used above a drop ceiling on a commercial job? Just sounds like a lazy EC that wants to take short cuts that could cost you later.

 

[ron]

Re: Rigidly and securely fastened

These are addressable type photoelectric smoke detectors served by a Siemens Cerberus (Pyrotronics) MXL Control Panel on a power limited signaling loop.
I also think he's trying to cheat the job. I even have a detail on the drawing showing the box attached to the concrete using anchors and screws, but he has the owners ear more time than I, and he has convinced him that attaching the box to the concrete ceiling will make it more difficult to serve the detector in 10 years when it gets dirty (it is part of a addressable FACP that is listed to determine when the detector is dirty and calibrate) or fails.

 

[ron]

Re: Rigidly and securely fastened

Another angle which might make this permissible is that Article 760 does not specifically reference 314.23 for box support.
Am I missing something? Is there no requirement for raceway and boxes when installing them for fire alarm systems in 760?

 

[ron]

Re: Rigidly and securely fastened

Found the reference in 760:
760.25 (NPLFA Circuit Wiring Methods) and 760.52 (B) (PLFA Wiring Methods and Materials) both
refer to 300.15, which in turn refers to 314.