A door protected with a contact cannot be opened more than what distance without initiating an alarm?

A door protected with a contact uses a magnetic switch to determine whether the door is closed or open. When the door is properly closed, the magnet and the switch are aligned, and the system remains in a non-alarm state. However, if the door is opened, this alignment is disrupted.

The standard for most security systems dictates that a door should not be opened more than 2 inches without triggering an alarm. This threshold is set to ensure a quick response to unauthorized access attempts, thus maximizing the effectiveness of the security system. By allowing a minimal distance before an alarm is triggered, security protocols provide a balance between operational convenience and the necessary security measures to protect against potential intrusions.

The other distances do not align with general best practices for door contacts in alarm systems. Distances shorter or longer than 2 inches may not provide the optimal security response necessary for effective monitoring and alarm response. Using 2 inches as a threshold helps to ensure that security measures are effectively engaged while preventing false alarms from minor incidents.