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Thread: Door Hold Open Magnets between 2 buildings

  1. #11
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    Quote Originally Posted by Strathead View Post
    I have never known of a supervised door holder circuit.
    Neither have I. It's a Class D circuit (NFPA 72-2010 12.3.4) and supervision would be an unnecessary expense.

  2. #12
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    Quote Originally Posted by nietzj View Post
    It's actually a tunnel between 2 buildings, each building has it's own fire alarm system, one Simplex the other Notifier. I would like to just put them on them one of the systems and add signage so folks will know when testing, kinda complicated, hate to have a system from one building controlling a smoke in another building but I think it makes the most sense. There is one set of doors and I could use either a relay or a relay based smoke, both systems are addressable.
    I don't profess to being a Fire alarm guru. I do hold a NICET 2 but I consider myself an electrician that does fire alarm. That said, I would like clarification s to why you are asking this question. My thoughts are this from a common sense perspective. Both doors don't need to be connected in any way. Each door can operate from its respective building with smoke detectors placed per the requirements of NFPA 72. And it will control the spread of smoke (the purpose) accordingly.


    I know what I don't know, and I know where to go to find it!

  3. #13
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    Quote Originally Posted by Strathead View Post
    I don't profess to being a Fire alarm guru. I do hold a NICET 2 but I consider myself an electrician that does fire alarm. That said, I would like clarification s to why you are asking this question. My thoughts are this from a common sense perspective. Both doors don't need to be connected in any way. Each door can operate from its respective building with smoke detectors placed per the requirements of NFPA 72. And it will control the spread of smoke (the purpose) accordingly.
    The purpose is to prevent fire/smoke from entering the tunnel and then entering the building where the fire event isn't taking place. That just complicates things for first responders if they receive notification of fire at adjacent addresses, and can delay investigation into the proper location.

  4. #14
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    Quote Originally Posted by gadfly56 View Post
    The purpose is to prevent fire/smoke from entering the tunnel and then entering the building where the fire event isn't taking place. That just complicates things for first responders if they receive notification of fire at adjacent addresses, and can delay investigation into the proper location.

    With an attempt to not be too disrespectful, I would like to push the wrong button. If Building A has smoke, either the area smokes will shut the fire door, or even that building doesn't have to shut all doors for any smoke anywhere, it can have smoke detectors dedicated to each door that only operate that door, the door to the tunnel from the smokey building is shut. If by some chance the smoke is in the tunnel or the door fails to block the smoke, at the point that it is important to close the door in building B, the smoke detector(s) in that building will shut that door.


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  5. #15
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    Quote Originally Posted by Strathead View Post
    With an attempt to not be too disrespectful, I would like to push the wrong button. If Building A has smoke, either the area smokes will shut the fire door, or even that building doesn't have to shut all doors for any smoke anywhere, it can have smoke detectors dedicated to each door that only operate that door, the door to the tunnel from the smokey building is shut. If by some chance the smoke is in the tunnel or the door fails to block the smoke, at the point that it is important to close the door in building B, the smoke detector(s) in that building will shut that door.
    Ahhh, but in a fully sprinklered building, you don't need smoke detectors in your corridors. So, if your purpose is to close the door in the event of a fire/smoke condition, you need a detector by each fire/smoke door. You might have smoke rolling down the corridor before your sprinkler activates, maybe long before depending on the nature of the fire and fuel. As it drifts by the tunnel door in building A it will close the door to A. However, you might get enough smoke in the tunnel to trigger the similar detector in building B. Now the responders get to play "Where is the fire?" Close the tunnel at A and B and the responders will go to the right building.

  6. #16
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    Door Holders Release by Smoke Detectors

    I only looked at the Appendix A because the idea was addressable detectors need signaling line circuit (SLC) two wires then an additional two wires for power to power the electronics inside the smoke detector base. You cannot have two separate controllers active in the same fire zone unless they are NRTL listed together.

    That is all I am posting, not a proposed solution and only the smokes are covered (not the door holder(s)) in the NFPA 72 diagram I text in my post. Not attempting to surmise a solution when the C&E martrix is not available and you have to monitor power in the article NFPA 72 10.17 to safely know if the cause (smoke) and the effect is (close a door) by releasing the power to de-energize the magnets.

    There are a few good ideas here in this thread.

  7. #17
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    Pathway Designator Class D

    Quote Originally Posted by gadfly56 View Post
    Neither have I. It's a Class D circuit (NFPA 72-2010 12.3.4) and supervision would be an unnecessary expense.
    A class D pathway is virtually hard to believe when NFPA 72 23.4.2 and 23.6 only allow Class A, Class B, or Class X for signaling Line Circuits (SLC) required for initiating device addressable detectors.

  8. #18
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    Quote Originally Posted by nec_addicted View Post
    A class D pathway is virtually hard to believe when NFPA 72 23.4.2 and 23.6 only allow Class A, Class B, or Class X for signaling Line Circuits (SLC) required for initiating device addressable detectors.
    But the reference to Class D was, I think, in relation to the door actuator circuit, not the detector(s) in and around the tunnel.

  9. #19
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    Listed Felay Within 3 Feet of appliance

    In this case the class D circuit applies between the FA unit to the relay. The relay must be within 3 feet of the door holder in the tunnel.

    21.2 General. 72–106 NATIONAL FIRE ALARM AND SIGNALING CODE


    21.2.4* A listed relay or other listed appliance connected to the fire alarm system used to initiate control of protected premises emergency control functions shall be located within 3 ft (1 m) of the controlled circuit or appliance.

    21.2.6 The installation wiring between the fire alarm control unit and the relay or other appliance shall be Class A, Class B, Class D, or Class X in accordance with Chapter 12.

  10. #20
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    Quote Originally Posted by nec_addicted View Post
    In this case the class D circuit applies between the FA unit to the relay. The relay must be within 3 feet of the door holder in the tunnel.

    21.2 General. 72–106 NATIONAL FIRE ALARM AND SIGNALING CODE


    21.2.4* A listed relay or other listed appliance connected to the fire alarm system used to initiate control of protected premises emergency control functions shall be located within 3 ft (1 m) of the controlled circuit or appliance.

    21.2.6 The installation wiring between the fire alarm control unit and the relay or other appliance shall be Class A, Class B, Class D, or Class X in accordance with Chapter 12.
    So one relay to control two widely separated doors seems to be out of the question then?

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