In an office environment, common courtesies like holding the door are expected and encouraged. However, this practice can make office security a little harder because it allows people to go through certain checkpoints without swiping their access badges. Pre-alarms work to counteract this, emitting an audible alarm that sounds 10 seconds before a door’s designated held open time has elapsed. While the held open time might be much longer for a front door or an entry into a conference room, more secure areas like laboratories or server rooms will need to have a relatively short span of time to enter. If the door doesn’t close within the held open time, a system alarm goes off, requiring you to investigate.
Pre-alarms cut down on this, letting employees and guests know that they have held the door open for too long. As long as they allow the door to close within 10 seconds of hearing the pre-alarm, the actual alarm will not be triggered and no alert will be sent out, preventing more work for you and your administrators.