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In its simplest form, the user activates the alarm by pulling the handle down, which completes a circuit and locks the handle in the activated position, sending an alarm to the fire alarm control panel. After operation, most fire alarm pull stations must be restored to the ready position using a special tool or key for the panel to be reset.
The alarm transmission methods covered under UL 365 can be categorized under standard line security or encrypted line security. The systems are required to operate within the limits of Class 2 remote control and signal circuits as defined by the National Electrical Code, NFPA 70. [15]
Dual-loop is a method of electrical circuit termination used in electronic security applications, particularly modern intruder alarms. It is called 'dual-loop' because two circuits (alarm and anti-tamper) are combined into one using resistors. Its use became widespread in the early 21st century, replacing the basic closed-circuit system, mainly ...
Some alarm systems serve a single purpose of burglary protection; combination systems provide fire and intrusion protection. Intrusion-alarm systems are combined with closed-circuit television surveillance (CCTV) systems to record intruders' activities and interface to access control systems for electrically locked doors. There are many types ...
Door and window sensors are also implemented in most home security systems. One part of the system is installed on the door or window itself while the other part is installed on the frame of the door or window. The two part system connects securely when a door or window is closed, creating a security circuit. [5]
An automotive wiring diagram, showing useful information such as crimp connection locations and wire colors. These details may not be so easily found on a more schematic drawing. A wiring diagram is a simplified conventional pictorial representation of an electrical circuit. It shows the components of the circuit as simplified shapes, and the ...
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The NFPA 72 "covers the application, installation, location, performance, inspection, testing, and maintenance of fire alarm systems, supervising station alarm systems, public emergency alarm reporting systems, fire warning equipment and emergency communications systems (ECS), and their components."