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Thread: Fire alarm NAC circuits

  1. #1
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    Fire alarm NAC circuits

    I've come across strobes and horn/strobes speced to be wired alternating circuits..like a/b/a/b ...anyone familiar with this?

  2. #2
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    came across a speaker strobe that was labeled A/V throughout the drawings, never figured out why it wasn't labeled S/S.
    jerryalan

  3. #3
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    Quote Originally Posted by jerryalan View Post
    came across a speaker strobe that was labeled A/V throughout the drawings, never figured out why it wasn't labeled S/S.
    Cause it is an Audio/Visual device?

  4. #4
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    Quote Originally Posted by GoldDigger View Post
    Cause it is an Audio/Visual device?
    Yes, that exactly.

  5. #5
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    Quote Originally Posted by mstrlucky74 View Post
    I've come across strobes and horn/strobes speced to be wired alternating circuits..like a/b/a/b ...anyone familiar with this?
    It was popular in NYC, or so I've been told. The Port Authority of NY and NJ has added a design guideline for fire alarm systems for the LaGuardia Terminal B project that says you can't lose more than 60% of the notification appliances in a space if there is a circuit failure. There is nothing in NFPA 72, the NYC building code or Appendix Q thereto that requires "A/B" circuiting. It may show up in a specification, or there may be an AHJ who has a "shirt-pocket" rule.

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