If you’re thinking…”I think she already wrote about this,” you’re right! A while back I had an article in Doors & Hardware about the requirement for electric strikes on fire door assemblies to be fail secure – this ensures that the keeper will remain closed to provide positive latching if power is cut. The article is here if you’d like a refresher.
But recently a question from a code official landed in my inbox: “Can an electric strike on a fire door be operated by a motion sensor?” For example, if a door is often used by people carrying boxes or other large items, could a sensor release the strike so the building occupants can just push on the door rather than turning the lever to exit?
There is nothing in the codes that would prohibit the use of a sensor to release an electric strike in the direction of egress. The lever handle provides free egress manually so the sensor is only for convenience. But what if the smoke and/or heat from a fire caused the sensor to malfunction and the keeper to release? The door could then be left unlatched and unable to prevent the spread of smoke and flames.
The same thing could happen with a card reader if someone used a “toggle card” which unlocks the strike until the toggle card is used again. I think this application should be treated like electric latch retraction panic hardware – the latch projects (or the strike keeper is secure) upon fire alarm. This would require a fire alarm contact that may not currently be typical of electric strike installations.
Here’s the section from NFPA 80 that is usually applied to electric latch retraction. I don’t like the use of the term “fail-safe,” but it is not being used to mean a fail-safe strike in this instance:
18.104.22.168.3 Latching arrangements that do not provide positive latching in the normal mode shall be permitted to be used provided that, in a fire emergency, the door becomes positively latched by means of an automatic fail-safe device that is activated by an automatic fire detector.
Questions for you:
Should an electric strike on a fire door be required to be secure upon fire alarm, similar to electric latch retraction panic hardware?
If you specify or supply hardware, is this a function that you are currently including in your operational descriptions?
Do we need a code change to make this more clear, or is the NFPA 80 language above sufficient?
Should a motion sensor be allowed to release an electric strike on a fire door?