National Electrical Installation Standards

Standards as High as Your Own

Monday, February 17, 2020


Hello, regarding smoke detectors and fire dampers on ducts. I have always connected them and seen them connected with FMC or BX cable because the duct could move or is not rigid, so I am looking for clarification. I was reading the IBC recently and came across "909.12.2 Wiring". In addition to meeting requirements of NFPA 70, all wiring, regardless of voltage, shall be fully enclosed within continuous raceways. The commentary reads "Wiring is required to be placed within continuous raceways, which provides an additional level of reliability for the system. The definition of the term “raceway” in NFPA 70 lists several acceptable types of complying raceway that can be used; however, manufactured cable assemblies such as metal-clad cable (Type MC) or armored cable (Type AC) are not included".

No one has said anything to me before, but you know how it goes, you don’t know until someone opens a can of worms...

Camilo Rodriguez



NOTE: All responses to questions submitted to the Code Question of the Day are answered at face value.

Hi Camilo, thanks for the question.

If Section 909.12.2 requires continuous raceways then that is the type of wiring method that is required to be used. AC Cable and MC Cable are cable assemblies and are defined in Section 320.2 and 330.2 respectively. The term raceway is defined in Article 100 as "An enclosed channel designed expressly for holding wires, cables, or busbars, with additional functions as permitted in this Code." The Articles covering raceways are provided in Chapter 3.

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