smoke detectors near elevators.

Are they required for fire alarm systems? It seems like all buildings I’ve been in that have fire alarm systems and elevators, have a smoke detector near the elevator, even if they don’t have them elsewhere.

They are tied into the elevator. This allows the elevator to disable itself in case there is a fire close by.

To be clear, a smoke detector needs to be located not more than 21.6 feet form the center of the elevator doors it is protecting. This detector is providing a very specific function associated with the elevator controller.

If an elevator lobby detector activates, the elevator will not allow passengers to exit on that floor.

specifically, those detectors are programmed to trip relays in the elevator control room that are connected to the elevator motor. When a lobby, machine room, or hoistway smoke detector is activated, the fire alarm system is tripped. The relays trigger the primary floor recall in the elevator machinery, which will instantly recall each elevator car in that bank, causing the fireman’s hat in the elevator car to come on, a warning in the car to sound, and the elevator will immediately cease operation and return non-stop to the “primary floor”. Once the elevator returns to the floor, the doors remain open (this serves two purposes, it allows firefighters to instantly confirm that nobody is or can be trapped in an elevator, and it allows them instant access to help with evacuation of handicapped occupants, or to transport emergency medical or firefighting equipment). The elevators cannot be used until either the fire alarm system is reset and the elevator is reset with a fireman’s key, or an authorized person turns on the “phase 2” switch inside the elevator.

The primary floor is usually the main floor where people enter the building. This is because fire can interfere with the elevator and possibly call the car to a floor where there’s a fire. A detector being activated in the primary floor elevator lobby or machine room will recall that elevator bank to a designated alternate floor (usually a basement with an exit, or a second floor) so that passengers aren’t brought to a fire on the primary floor.

Four years ago, I was doing a fire alarm inspection in a nearby hospital. The hospital has 11 habitable floors, plus mechanical rooms and a rooftop helicopter landing above that. I arrived before 8:00 AM before the other inspector. I placed the system on test with the monitoring center, and informed the hospital switchboard operator that we were testing and to ignore any signals. Before I had the system’s signals and auxiliary functions disabled (shortly before 8:00) I heard the 4100 panel go into alarm and the whoops and code red message played. I saw that the rooftop elevator machine room smoke detector had activated.

This particular hospital has a cafeteria on the 11th floor that sees a large flow of customers at 8:00. A bank of six elevators had been recalled and each car was sitting on the ground floor, doors open, fire hat indicators lit, as expected. There was a critical medical case that had to go upstairs to the 7th floor. Using a fireman’s key, I kicked everyone out of the car and took him to the 7th floor in fireman’s mode, and called 911 from my cell phone since the alarms were being ignored by the central station and the switchboard operator. I continued up to the 11th floor and turned the fireman’s key to “hold”, which parks the elevator at that floor with the door open and disables that elevator from being used until you turn the fireman’s key back to on. As usual, the strobes were flashing and even though there were signs saying “in case of fire, elevators are out of service, use stairs” there were sheeple repeatedly pushing the call button. I went through the crowded cafeteria and up a service stairway to the roof, just in time to see two men exiting the elevator machine room with fire extinguishers.

The fire department arrived within minutes, and an elevator company rep was soon on site. The brakes had failed in that particular elevator motor, and the smoke tripped a photo detector right above the motor. The elevator company rep made some comment about this possibly not being able to stop at the top floor like it was supposed to, and it’s good that the fire alarm system instantly stopped it from continuing to go up.

The movie The Towering Inferno demonstrates (however quite dramatic and exaggerated) the importance of elevator recall.

I have to ask though, have there ever been smoke detectors in the elevators themselves?

Yes, there has been. I went to a mall once and I waled into the elevator and saw a detector. Plus a Siemens Speaker/Strobe in there with a Stopper over it.

A stopper cover over an NA? That sounds odd. I’ve only ever heard of them being installed over pull stations.

The NA protective covers are also called Stoppers:

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One day, an elevator motor over heated and smoked, activating the smoke detector that I believe to be in the elevator shaft. This happened at my city hall.

The most elevators I have ever tied a fire alarm into have all of the floors above the ground level, minus the ground level itself on the primary recall (car to first floor) relay, the ground level tied to the secondary recall relay (car to alternate level). Then, a smoke detector at the top, at the bottom, and in the machine room trip a hat relay and the appropriate recall relay based on pit/shaft and machine room locations. Additionally, if a sprinkler head is present in the elevator shaft, a heat detector must activate a power shunt switch before the sprinkler head activates, thereby disabling the elevator entirely. The fire alarm sensors and relays must be reset before the elevator controller will re activate in a normal mode. A fair amout of programming is required to make the above happen on any type of addressable fire alarm system.


There is sooo much more work done with that than I thought there was.