Why This Elevator Smoke Detector Requirement Is the Pits
Fire/life-safety expert Shane Clary bucks an NFPA 72 code requirement and explains why the onus should instead be on the building owner.
Since the 2013 edition of NFPA 72, The National Fire Alarm and Signaling Code, there has been a requirement that a smoke detector be installed with the elevator pit if a sprinkler is also installed within the pit. The sprinkler has been placed there due to a history of fires occurring within pits because of a buildup trash that can occur within a pit.
I am not in favor of having smoke detectors being located within the pit. The issue regarding a buildup of trash within the pit should be a maintenance requirement of the building owner. The pits themselves can become dirty and be subject to unwanted alarms. The location of the detector also is difficult to reach for inspection and testing. Typically, arrangements with the elevator service provider needs to be made prior to the inspection call. The fire alarm inspector should never enter a pit without an elevator technician being onsite.
There were no direct references for a smoke detector to be installed within the pit through the 2010 edition. During the proposal stage for the 2013 edition, there was a proposal by Peter Leszczak of the U.S. Department of Veterans Affairs to add a new provision within the standard.
21.3.6 Smoke detectors shall not be installed in elevator pits.
The substantiation that was provided was that “elevator pit smoke detectors only provide nuisance fire alarms and that these areas are typically very dirty.” There were no negative votes for the Technical Committee on Protected Premises Fire Alarm Signaling Systems.
It was during the comment phase that this took a 180. Thomas Hammerberg representing the Automatic Fire Alarm Association submitted a comment to change the Technical Committee action to a reject, which would remove the restriction. The substantiation was, “Presently there are many smoke detectors located in elevator pits that are operating properly and without nuisance trip problems.” Hammerberg also referenced detection products that are designed for a harsher environment.
The Technical Committee accepted principle for this recommendation. The revised text that was agreed to was:
21.3.9 Where smoke detectors are installed in the pit to initiate elevator recall, the smoke detector shall be listed for the environment.
The Technical Correlating Committee then made further refinements by directing that 21.3.9 be changed to:
21.3.9* Smoke detectors shall not be installed in elevator pits to initiate elevator recall unless the smoke detector is listed for the environment.
Within the 2013 edition, in addition to 21.3.9, which became 21.3.8, the following provisions relative to detection with elevator pits was now within NFPA 72.
When sprinklers are installed in elevator pits, automatic fire detection shall be installed to initiate elevator recall in accordance with 18.104.22.168.1(c) of ANSI/ASME A.17.1/CSA B44, Safety Code for Elevators and Escalators, and the following shall apply:
(2) Where sprinklers are located in the bottom of the hoistway (the pit), fire detection device(s) shall be installed in the pit in accordance with Chapter 17.
21.3.9 * If ambient conditions prohibit installation of automatic smoke detection, other automatic fire detection shall be permitted.
With the publication of the 2019 edition, the requirements have stayed the same, just with a change with the order of the paragraphs and some minor tweaks with the language. The key is that if there is installed a sprinkler in the pit, that the designer needs to take into consideration the environment that the detector will be in.
As was mentioned by Hammerberg in 2012, there are other means of detection technology that is available. This includes air aspiration systems in which the detector is through piping in which the air is being sampled and if the products of combustion is detected, there would be an activation of the system.
These system also can be tested without the requirement of entry into the hoistway or pit. A means of cleaning the sampling ports must be provided as well, which can be the injection of compressed air into the sampling tubes so as to blow out any dust or accumulated dirt that may have built up.
As I stated at the top of this article, my preference is that the requirement for detection be removed in both NFPA 72 as well as ANSI/ASME A17.1/CSA B44, Safety Code for Elevators, and Escalators. This will most likely not occur so the selection of the most optimal means of detection is paramount.
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