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Thread: 120Vac smoke detector with alarm relay

  1. #1
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    120Vac smoke detector with alarm relay

    I need to supervise 120Vac interconnected smoke detectors with the building fire alarm system. The smoke detectors have a wiring harness that have the 120Vac leads and alarm contact leads. Is it acceptable to have the line voltage conductors and the fplp cable in the same box the device is mounted to? Not sure how else to do it.

  2. #2
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    Quote Originally Posted by bbomaha View Post
    I need to supervise 120Vac interconnected smoke detectors with the building fire alarm system. The smoke detectors have a wiring harness that have the 120Vac leads and alarm contact leads. Is it acceptable to have the line voltage conductors and the fplp cable in the same box the device is mounted to? Not sure how else to do it.
    Great question. I assume you are going to connect a monitor module from the fire alarm system to the relay output? I doubt you can install a suitable barrier in the box the fire alarm is mounted to. Can you couple a second box to the fire alarm mounting box and feed the conductors from the relay into that box? That way you won't mix power line and Class 2/3 in the same box.

  3. #3
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    Yes a monitor module will be used in a separate box. Coupling boxes won't be feasible as the smoke detector box is fiberglass and in drywall. I haven't found a barrier for a round box.

  4. #4
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    4x4 box with divider and plaster ring with round opening?

    I have no idea if this would work, just popped into head.
    "Electricity is really just organized lightning." George Carlin


    Derek

  5. #5
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    Perhaps gentex needs to make a barrier on the back of their smoke detector with two separate harnesses.
    Last edited by bbomaha; 01-13-18 at 12:41 AM.

  6. #6
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    Exceptable would be acceptable to me.

  7. #7

    120 VAC Smoke Detectors (NEC Article 760)

    Branch circuits supplying power to single and multiple-station smoke alarms such as those in dwelling units are not subject to the requirements of article 760. Therefore listed for purpose smoke detection matched to a fire alarm panel and it's listing might fall under an exception not contemplated. UL circuit directory and FM Directory in its listing may offer the identical comment in your follow up consideration reply.

    Since the OP (PLFA) also is centered around enclosures and conductor types try looking at 760.3, 760.121, 760.139, 760.179 then go back to 760.135 (E) to determine if those satisfy your OP with concerns about the detection and the fire alarm panel. It is entirely possible the smoke detectors are UR and not UL or that some detectors in your SLC may be incorporated with 770.113 (B) and those are used for a smoke control system which could have 120VAC with damper controls as a cause and effect matrix.

  8. #8

    120VAC Smoke Detector (Gentex)

    Quote Originally Posted by nec_addicted View Post
    Branch circuits supplying power to single and multiple-station smoke alarms such as those in dwelling units are not subject to the requirements of article 760. Therefore listed for purpose smoke detection matched to a fire alarm panel and it's listing might fall under an exception not contemplated. UL circuit directory and FM Directory in its listing may offer the identical comment in your follow up consideration reply.

    Since the OP (PLFA) also is centered around enclosures and conductor types try looking at 760.3, 760.121, 760.139, 760.179 then go back to 760.135 (E) to determine if those satisfy your OP with concerns about the detection and the fire alarm panel. It is entirely possible the smoke detectors are UR and not UL or that some detectors in your SLC may be incorporated with 770.113 (B) and those are used for a smoke control system which could have 120VAC with damper controls as a cause and effect matrix.
    The additional concern and the caveat here is I went to UL Online Certification Directory and typed in Gentex-I do not view any smoke detectors listed under their name. Do You know the model number of the detector and is it labeled? For use with the Fire Alarm Panel you refer. Certainly NFPA 72 performance testing certificate must be aquired to use them together.
    http://database.ul.com/cgi-bin/XYV/t...626.1515864928

  9. #9
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    Quote Originally Posted by nec_addicted View Post
    The additional concern and the caveat here is I went to UL Online Certification Directory and typed in Gentex-I do not view any smoke detectors listed under their name. Do You know the model number of the detector and is it labeled? For use with the Fire Alarm Panel you refer. Certainly NFPA 72 performance testing certificate must be aquired to use them together.
    http://database.ul.com/cgi-bin/XYV/t...626.1515864928
    Search for Gentex they are listed.

  10. #10

    Gentex

    Acknowledge is part of UROX and UTGT

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