The activation time (in seconds) of a standard response (RTI of 85 m^1/2s^1/2), Ordinary Temperature (65 deg C) heat detector within a room that has an initial temperature of 22 deg C and exposed to a ceiling plume at 78 deg C traveling at 2.3 m/s is most nearly what time?
a. 10 s
b. 36 s
c. 54 s
d. 82 s

Solution | Posted 09/17/20

NFPA 72 requires a battery test be run including removal of the main power supply, waiting the full-length standby time, then activating the fire alarm system for the full alarm time. After the alarm time, the battery voltage is required to be tested.

What is the pass/fail mark for the battery voltage?

In theory, if the battery output still has 20.4 V, then the last appliance on a NAC circuit would still get a minimum of 16 V and everything still functions correctly. I just can't seem to find a code reference whether 20.4 V is the correct voltage to use (where a voltage reading below 20.4 V fails the battery). 

Thanks in advance.

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I am a municipal fire inspector. We have a new high school, fully sprinklered, that has residential stoves in a classroom. These are protected with UL300A hoods.

Are these hoods required to be connected to the fire alarm?

Common sense would indicate that if there was a fire hot enough to release the UL300A system, that the building occupants could be in danger and the fire alarms should activate, however, I cannot find a code reference for this. The architect is saying the stoves are residential so only residential requirements apply.

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Solution | Posted 08/21/20

​Determine the response time index (in ft^1/2 s^1/2) for a 160-degree F heat detector with a listed spacing
of 30 feet.
a. 44
b. 80
c. 169
d. 180

Solution | Posted 07/30/20

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 working within a campus environment, and costs are something that always arise at some point during ITM conversations.

Does anyone have a great resource or tool to help to estimate a ballpark cost of ITM over a life of the building?

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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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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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Solution | Posted 10/18/19

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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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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Solution | Posted 08/06/19

Solution | Posted 07/31/19

Solution | Posted 07/19/19

A forensic investigator is trying to determine approximate timing of events after a fire within a hospital basement. A quick response sprinkler (RTI of 50 m^1/2s^1/2), Ordinary Temperature (65 deg C) was within a room (2.1 m high ceiling) that has an initial temperature of 73 deg F and was exposed to a ceiling plume at 205 deg F traveling at 1.3 m/s. Approximately how long should it have taken the sprinkler to activate?
     a. 2 s
     b. 16 s
     c. 33 s
     d. 38 s

Solution | Posted 07/16/19

What governs the minimum conduit size for fire alarm circuitry?

Is it just based on the ampacity factors in the National Electrical Code similar to any power circuits, or is there some other section I should be referencing from NFPA 72 or the NEC? Any help is greatly appreciated.

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Solution | Posted 07/01/19

Do you often come across AHJs who require manual pull stations at every exit, regardless of the occupancy and regardless of whether they're allowed to be omitted based on a fully-sprinklered building? 

I've come across it a few times and we certainly see some ordinances written in - I'm just curious if it's something you have seen and whether you choose to fight it or just include the pull stations.

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