Should return air duct smoke detectors associated with a fan system close only the associated damper and shutdown the fan or close all dampers on the system (including supply return spill and outside air)?

How should outside air and spill air fire smoke dampers be controlled? Should these to be controlled by fire alarm?

Thanks in advance.

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I’m confused by the field of view intent of NFPA 72 for synchronization.

Do two adjacent rooms with a door between them each with strobe coverage require synchronization?

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Question for AHJs and inspectors:

Do you occasionally see fire alarm strobes mounted on the ceiling that appear to be for a wall-mounted orientation (e.g. they are rectangular and have the word "FIRE" on the side)?

I know some of these are actually for ceiling mounted applications but I've run across some that are wall-mounted only. I think the Wheelock brand might be an example? Stuff like this is hard to tell in the field for an existing building (with no documented cut sheets for what was submitted).

Anyone have tips or tricks for this?

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What constitutes a "drop" on a fire alarm Class A circuit?

NFPA 72 12.3.8.1 (2016 Edition): 
"The outgoing and return circuit conductors shall be permitted in the same cable assembly, enclosure, or raceway only under the following conditions:
(1) For a distance not to exceed 10 feet where the outgoing and return conductors enter or exit the initiating device, notification appliance, or control unit enclosures.
(2) Single drops installed in the raceway to individual devices or appliances.
(3) In a single room not exceeding 1000 sq ft in area, a drop installed in the raceway to multiple devices or appliances that does not include any emergency control function devices."

For this project in question an appliance is located approximately 12 feet away from a device. The circuit runs from the device, out 12 feet horizontally, down a wall a few feet, then back up and back to the first device. 

In my opinion, the outgoing and return circuit exceeds 10 feet so it would not qualify as Class A wiring. However, the contractor is calling this a "single drop" to an individual appliance, so he feels it qualifies as exception (2) above.

Is this considered a single drop if it's only serving an individual appliance?

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Our common CRAC Units (Cooling, Refrigeration and A/C) for data centers only cool the air directly from the data center and back into the data center.

Do these need to be shutdown with the use of a total-flooding clean agent system? 

If the CRAC unit is only exchanging air within the same space then I'm not sure what harm it would do if it's running during or after clean agent discharge. I'm curious if I'm off the mark here, thanks!

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When an elevator does not have an elevator machine room, where should the fire alarm relays for the elevator be located?

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Do underground gate valves for fire main water supplies have to be monitored and supervised?

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Are there special requirements for fire alarm strobes on the exterior parts of the building (courtyards, etc)? Thinking that direct sunlight may interfere with the strobe.

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I do inspections for fire alarm systems. It's not something that is brought up often and is generally not an issue, but I am trying to educate myself on what the correct procedure is to determine the conduit size for fire alarm.

Could someone point me in the right direction? Thanks in advance.

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NFPA 72 states that audibility from a fire alarm system is required to be provided throughout a building. Most jurisdictions are less concerned with attaining audibility in small, non-normally-occupied rooms such as janitor closets, small electrical rooms, or small mechanical rooms. However, several military reviews have pointed to exactly these rooms and asked how audibility is going to be achieved. 

I typically provide speakers just outside of these groups of rooms such that there should be an achieved audible level, but how could I prove that during the design phase?

Is there any calculation for audible loss through a door or software that could model this loss?

I feel like there's a good handful of variables that play into whether audibility is achieved in these small rooms that may be difficult to predict.

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Is there a complete list of points I need to monitor with fire alarm for a diesel driven fire pump?

I can't seem to find a comprehensive/definitive list in NFPA 20 or 72, but I would imagine at least one or more of the following would need to be monitored by code: fire pump running, primary sensor failure, low fuel level, main disconnect in "off" position, main disconnect in "manual" position, low pump room temperature, flowmeter left on, loss of AC power supply, loss of battery (load side of DC overcurrent), over-speed, and engine trouble (low oil, over temp, other?).

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A dormitory has residential rooms which house two students. There is a traditional sleeping area approximately 12 ft x 12 ft, and a hallway with a bathroom and closet in-between the sleeping area and the main corridor.

Separating the sleeping area and the unit hallway is an opening about the size of a door opening (but with no door). This project is still in design.

How shallow would the header on this opening need to be (distance from the ceiling), in order to avoid requiring a smoke detector in the sleeping area and the hallway?

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I'm considering testing for NICET fire alarm certification. What I don't yet know and would be very interested in is who typically prepares fire alarm shop drawings? 

Do freelance fire alarm designers/engineers make up a large portion of shop drawing preparation, or is it mostly all completed by a fire alarm company's designer? Do large manufacturers (Simplex/JCI) complete all of their own shop drawing work with in-house designers?

Thanks in advance - I'm trying to get a better perspective for my career.

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I've looked for it but I'm having a tough time coming up with the code section. Where does the requirement for a bell on the face of the building come from?

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We have a project where a control module is connected to the mechanical controls that is programmed to the variable frequency drive for a fan on a large unit. When a duct detector senses smoke, the control module (which is normally-open circuit) will close the circuit, sending a signal to the mechanical controls which shuts down the unit.

On this project we had a bad set of control modules that didn't work. We discovered this in testing with the local jurisdiction, and swapped out the modules and the system now works correctly. 

Both the jurisdiction and I wondered whether this normally-open arrangement is acceptable. If a control module were to fail, the duct detector would not be able to close the circuit on the module and the fan would remain running. In this scenario, there would be no supervision or way to know that the control module failed other than someone standing at the fan or finding the issue during testing.

My inclination is that in the future these modules could be normally-closed and open upon duct detection. That way if the module fails and opens on its own, the unit will shutdown in a "failure" mode.

Is it code required that this arrangement be fail-safe?

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We have a machine room-less elevator where the motor is located on top of the elevator cab and the elevator equipment is located within the elevator shaft.

NFPA 13 (2016) 8.15.5.3(2) allows sprinklers to be omitted from the hoistway of "traction elevators" where the hoistway is "protected by smoke detectors, or other automatic fire detection installed in accordance with NFPA 72", and several other requirements.

NFPA 72 (2016) 21.3.3 states that only the elevator hoistway and elevator lobby smoke detectors or other automatic fire detection (as permitted by 21.3.9) shall be used to initiate Phase I Emergency Recall Operation. 

NFPA 72 (2016) 21.3.9 states that if "ambient conditions prohibit installation of automatic smoke detection" that other automatic fire detection initiating devices shall be permitted.

What type of ambient condition in an elevator shaft would qualify as prohibiting smoke detection? 

I understand smoke detectors in elevator hoistways can cause nuisance alarms (NFPA 72 2016 A.21.3.9) and are very difficult to test and replace within elevator shafts, so in my opinion a heat detector would be better for elevator recall in the shaft if it's allowed by code.

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