Here's what happens when an outdoor detector that was not rated for such a specification is installed: rust.
A reader wrote to ask advice for a particular type of fire alarm installation that others of you may have encountered. The reader traveled to the southwest U.S. to help with the installation of a fire alarm system at a large private school. Unlike the majority of the country, many of these western school buildings have no interior hallways for the students to walk between classrooms. These structures resemble a two-story motel back east. The first level is at ground level and the second level is a landing that is actually a steel-grated catwalk connecting the second floors of two school buildings. The second level has no overhang of any type (what, it never rains?) and both levels are totally exposed to the outdoors and other elements. There is an elevator in the facility.
The question is: "Is there really a rule for recall when the elevator has only two floors and both doors open to the outside? NFPA 72 requires heat and smoke detectors be installed on or within one foot of the ceiling. Since there is no ceiling or overhang to collect heat, nor mount the detectors, how do I install a detector and still meet code?"
"To complicate matters, the elevator installer refuses to call for the state elevator inspection unless I install a smoke detector outside the elevator door. AND, the fire marshal will not sign off if there is a smoke or heat detector installed outside the elevator door, because it would be exposed to the elements. I don't see a way out of this-do you?"
A. When met with a situation this complex you have to address everyone's concerns. First, is the fact that you suggest that the elevator code doesn't apply in this situation. The ANSI elevator safety requirement for recall doesn't distinguish where the landing is located. If an elevator can take you there, then you will need to disable that possibility during a fire. Your only choice is to recall the elevator to the other floor. It's really that simple.
B. You are correct, in your second concern, when it comes to needing a ceiling when using spot-type detectors. However, NFPA 72 has added some clarification in the 2010 edition that speaks to your situation (188.8.131.52.4*). "If the intent is to initiate action when smoke/fire threatens a specific object or space, the detector shall be permitted to be installed in close proximity to that object or space." The asterisk sends you to the Annex where it explains further: "There are some applications that...when specific objects or spaces are threatened by smoke or fire, such as at elevator landings that have ceilings in excess of 15 feet..." (as in the installation at the school). It continues: "In high-ceiling areas, to achieve the desired initiation, such as for elevator recall...detection should be placed on the wall above and within 60 inches from the top of the elevator door(s)..." Hopefully, this height allowance will also allow you to place the detector out of easy reach of the students. If not, a listed wire guard might be considered.
Rule is for smokes, not heat, for now
Note that rule 184.108.40.206.4 is only found in the smoke detector section and not in the heat detector section of NFPA 72. The principle is the same and perhaps some reader will submit a proposal to add similar language to the heat detector section for the next edition of 72. Until then, a little common sense should allow the same principle to be applied to heat detectors, as well, especially since they are being used as a substitute for smoke detection.
The elevator mechanic will be disappointed since a heat detector will have to be used in place of a smoke detector. If he objects, tell him to check his elevator code, "Safety Code for Elevators and Escalators" (ANSI/ASME A17.1). It isn't just his code, it's yours as well, because NFPA 72 Chapter Two requires your compliance with it in connection of the elevator recall and control functions. In the past, the elevator code only mentioned smoke detectors, however that mistake has been corrected in recent editions and no one should be insisting on the use of smoke detectors in unsuitable areas such as parking garages and outdoor landings anymore.
This brings us to the last concern-the local building inspector's statement that he won't approve heat or smoke detectors to be installed where they are "exposed to the elements." Detector manufacturers, UL and NFPA 72 all prohibit smoke detectors from being installed in environments that are outside of their listing requirements. Therefore, you will have to use heat detectors that have been listed for the application you have encountered. These detectors will be hermetically sealed so they are dust and moisture proof. A weatherproof box will be required and splices within the box should be accomplished with silicon-filled connectors. The conduit and connectors must also be listed for outdoor use. (Don't forget to add lightning arrestors, UL497B, for all fire alarm wiring you run outdoors, per Article 800 of the NEC.) I don't think the building inspector will veto outdoor listed equipment. If he still doesn't want the detectors "exposed to the elements," then it becomes the school's problem and they will have to build a roof over the landing(s).
You are the fire alarm expert
I can see how you could feel overwhelmed by all of these issues being hurled at you from both sides. But when each problem is addressed individually, you should have no problem getting the job done correctly. Remember, being the fire alarm expert on the job means you have to become familiar enough with the code and its many nuances to find solutions when complications arise. This ability means the customer will see YOU as the problem solver, and will trust in and rely on you when more fire alarm work is needed.
Greg Kessinger is SD&I's longtime resident fire expert and regular contributor to the magazine. Reach him at firstname.lastname@example.org.