Enhancing Building Security with Effective Deflection Alarm System Design

In a well-designed building, residents would not have to input their access code on multiple devices or deal with hiccups that slow them down or distract their attention. Building security nuances is about reducing opportunities for criminal behavior and increasing comfort and efficiency.

Deflection Alarms

deflection alarm system design sends an electrical signal to the security system to indicate a possible threat. This can be a strong deterrent as the alarm might make would-be criminals think twice before entering your premises.

Upon deflection detection, the security system will immediately respond to the threat. This will be based on what is configured with the system and may include response modes such as “alarm only,” “low voltage,” or non-lethal electric fence” (NLEF).

A grid wire sensor is an enamel-coated number 24 or 26 American wire gauge (AWG) solid-copper wire that maintains a continuous electrical current. When the sensor is deflected, it will break contact with one of the spring contacts 77 or ring contact 78, alerting the security system. Alternatively, the sensors can be equipped with a pressure mat that detects a force on the mat, which would break contact.

Design Considerations

ESS system software should provide for monitoring all sensors, local processors, and alarm-annunciation communications links. It should also include the capability to record and display all occurrences of sensor-alarm conditions that have not been annunciated.

Audible alarm devices should be provided to alert the operator in addition to visual alarm displays. The audible alarm may consist of a ringing bell or the generation of a steady or pulsating tone by an electronic device. A silence switch should allow the operator to temporarily quiet an audible alarm before resetting it.

Detection thresholds of exterior sensors must be high enough to reliably detect a penetrating intrusion but low enough to limit nuisance and environmental alarms. Most exterior sensors are susceptible to site conditions such as wind, rain, and snow that will cause a change in the electromagnetic-field signal monitored by the sensor. Some buried, wire-mesh or grid-wire sensors are more sensitive to these expected conditions than other sensor systems. Dual-technology sensors combine an active ultrasonic or microwave sensor with a passive PIR sensor to reduce susceptibility to these expected site conditions.


The cabinet preferably includes a mechanism for sensing the deflection of one or more wire strands and providing an immediate response to such deflection. The resulting response may include a combination of “alarm only,” “low voltage,” and “nonlethal electric fence” (NLEF) signals.

A non-conductive collar 88 defines a hole 92 aligned with one or more bores 94 in both cartridge housing halves. The insertion of a pin (conductive or non-conductive) in each bore 94 prevents the contact portion 76 of the deflection bar from contacting the spring contact 77 and closing the electrical circuit.

A battery circuit containing two 6-volt lantern-type batteries provides power to the sounder. A key switch within the sounder circuit enables you to turn the sounder off and on when needed. You can also reset the circuit by opening a door and breaking the loop circuit. The system ideally has a test mode that you can run to make sure everything is working as it should.


Deflection strategies can help to protect your network against cyber attacks by monitoring unused ports and services. By detecting unusual traffic patterns, these deflection techniques can expose hackers and divert them toward bogus data instead of your real information.

Control Panel: The “brains” of the system that analyzes information from all sensors and sends commands to each device. Typically, this is a wired connection, but it can also be wireless.

Glass Break Sensors: Detects sound waves emitted by broken windows or door glass and triggers an alarm when a potential intrusion is detected.

Door and Window Contacts: Sensors that trigger an alarm when they detect that doors or windows have been opened without authorization.

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