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NFPA 99 - 2012 ref 5.1.9.1 subparagraph (11)

  • Tuesday, November 05, 2019 7:02 PM
    Message # 8093665
    Cary Darden (Administrator)

    I’m curious as to what the consensus view is on what is meant by the term “free-air” in the reference below:

    (11) 

    Where used for communications, wiring from switches or sensors that is supervised or protected as required by 517.30(C)(3) of NFPA 70National Electrical Code, for life safety and critical branches circuits in which protection is any of the following types: 

    (a) Conduit

    (b) Free air

    (c) Wire

    (d) Cable tray

    (e) Raceways


    I have seen this defined as wireless communications, as well as cable run not in a cable tray or raceway.  Thoughts?

  • Wednesday, November 06, 2019 10:29 AM
    Reply # 8094729 on 8093665

    Wireless

  • Wednesday, November 06, 2019 5:32 PM
    Reply # 8095283 on 8093665
    Mathis Carlson (Administrator)

    Free Air in the electrical sense is dealing with the protection of the wire within it's assembly. Free Air is typically looked at as the separation of each conductor within an assembly by a free air space of at least 100% the size of the conductor. The space allows for heat dissipation and protection of the conductor.
     

  • Thursday, November 07, 2019 3:04 PM
    Reply # 8096991 on 8093665
    Cary Darden (Administrator)

    What I have read on the term "free-air" in NEC lines up more with what Mathis said.  Don, what supporting information do you have on why it would be wireless?  I'm not sure what the intent is, but I would like to find out

  • Thursday, November 07, 2019 3:20 PM
    Reply # 8097017 on 8093665
    Cary Darden (Administrator)

    I found this in the 2011 report on comments (for the 2012 revision of NFPA 99), this was where the term free air made it's way into this section of the code so far as I can tell.  There is a mention of free air and the committee statement mentions allowing for new technologies that are not wire based.  However, it seems like subparagraph 12 speaks to this primarily. 


    Is it possible that the term "free air" wasn't meant to refer to how it is used throughout the rest of NEC?  If so it was a confusing choice to put that term within the same paragraph as a reference from NEC.


    Submitter: Jim Lucas, Tri-Tech Medical Inc.

    Comment on Proposal No: 99-260

    Recommendation: Revise text to read as follows:

    Wiring from switches or sensors that is supervised or protected as required

    by Alarm electrical components with power requirements above 24 volts shall

    comply with Section 517.30(C)(3) of NFPA 70, National Electric Code, for

    emergency system circuits.

    Substantiation: The goal is to provide continuous surveillance that is

    supervised or protected. Current verbage restricts new technologies such as

    optical data transfer, (ie. fiber optics or laser), Ethernet, and electromagnetic

    (ie. wireless).

    Committee Meeting Action: Accept in Principle

    Revise text to read as follows:

    (9) Power for master, and area alarms, sensors, and switches, from the life

    safety branch of the emergency electrical system as described in Chapter 6.

    (11) Where used for communications, wiring from switches or sensors that is

    supervised or protected as required by Section 517.30(C)(3) of NFPA 70,

    National Electrical Code, for life safety and critical branches circuits in which

    protection is any of the following types: conduit, free air, wire, cable tray, or

    raceways.

    (12) Communication devices that do not use electrical wiring for signal

    transmission will be supervised such that failure of communication shall

    initiate an alarm.

    Renumber existing paragraphs:

    (12) to (13)

    (13) to (14)

    (14) to (15)

    Committee Statement: This change will permit new technologies that are not

    wire based.

    Number Eligible to Vote: 22

    Ballot Results: Affirmative: 20

    Ballot Not Returned: 2 McManus, J., Shoemaker, E.



  • Friday, November 08, 2019 7:31 AM
    Reply # 8097854 on 8093665

    Please look at the paragraph:


    Where used for communications, wiring from switches or sensors that is supervised or protected as required by 517.30(C)(3) of NFPA 70National Electrical Code, for life safety and critical branches circuits in which protection is any of the following types: 


    The term free air is referring to how the wiring is run, and has nothing to do with wireless or this paragraph wouldn't say communications using wiring.

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