Fire alarm cabling

[rpjms500]

I am trying to solve a problem for a customer. The customer has duct detectors that the fire marshal is requiring to connect to the fire alarm system. The detectors are local to each AHU & are powered by common 120VAC, all connected with BX 14/2 cable back to a breaker. The detectors are multi-volt detectors (24VDC/AC 120VAC). In an attempt to save the customer money, can we connect the BX cable to a UL Fire rated 24VDC power supply and satisfy NEC for fire alarm system wiring? The contacts on the detectors will be monitored by a UL Fire rated wireless transmitter. Connecting the power cable to a 24VDC UL Fire rated power supply will allow for detector reset at FACP reset.

The real question is, can I use the existing BX cable for the power or do I need to pull new fire cabling?

Can anyone site chapter & verse? I need to satisfy AHJ.

Thanks

 

[tom baker]

Re: Fire alarm cabling

760.52 Wiring Methods and Materials on Load Side of the PLFA Power Source.
Fire alarm circuits on the load side of the power source shall be permitted to be installed using wiring methods and materials in accordance with either 760.52(A) or (B).

Installation of non?power-limited fire alarm circuits shall be in accordance with 110.3(B), 300.11(A), 300.15, 300.17, and other appropriate articles of Chapter 3.
Exception No. 1: As provided in 760.26 through 760.30.
Exception No. 2: Where other articles of this Code require other methods.

The way I read this it can be a chapter 3 wiring method. There may be something more restricitve in NFPA 72.

 

[rpjms500]

Re: Fire alarm cabling

Thank you for your help!