If you are considering including a security alarm in your house system and are unsure where to begin, here is a useful list of the most common types of security alarms and how they are intended to function. Typically, the siren itself is centrally located, like the security control panel, but alarms can be triggered by a variety of sensors that operate in different ways, based on what kind of protection homeowners prefer.
Note: Generally speaking, these listed devices can all be used with either wired or wireless systems. Wired systems are more expensive to install, but also tend to be more reliable and accurate. Wireless systems use radio waves to communicate alarm signals, send messages to security alarm companies, and turn on sirens. They are cheaper, but may not offer the same dependability, particularly over long distances.
Security Alarm Sensors to Consider
1. Contact Sensors
Contact or magnetic sensors are one of the most common types of security alarms. They are installed on doors or windows in two parts. One part houses a magnet or magnetic current, the other houses a switch that turns on when near the magnetic.
If the two are separated, the switch flicks off, the circuit is broke, and the control panel initiates the alarm. When the security system is armed, this type of alarm is activated by both normal entry (i.e., with a key or through any unlocked windows) and forced entry, making it a versatile, highly useful security alarm when you want to prevent any type of entrance into your home.
2. Photobeam Alarms
Photobeam alarms use basic, focused light beams. When the beam is broken, the alarm sounds. Photobeams are useful for indoor security, particularly if you have a specific room you want to protect (they are also handy for small businesses). They are less useful outdoors, when windows, animals, and objects may accidentally trip the alarm.
Most versions come with twin sensors that send and receive beams — some are even dual-sided to allow for multiple beam directions. The photobeams can be set at different “frequencies” to allow for greater customization.
3. Motion (PIR) Sensors
PIR refers to Passive Infrared Motion, a technology designed to detect movement before it activates a security alarm. The infrared sensor picks up temperature changes in the nearby air — if the change is great enough, the sensor sends the signal. This is particularly useful for outdoor alarms, where shifting branches or shrubs will not affect temperature changes, but a large heat source like a human will.
Like many motion-based sensors, a delay is often built into the alarm, so that owners who accidentally trigger the alarm can enter a security code before the siren sounds.
4. Ultrasonic Detectors
Ultrasonic detectors are very similar to PIR sensors, but instead of detecting heat they use sound waves that sense any type of movement. While ultrasonic detectors are not as useful in outdoor systems, they can easily cover an entire room indoors, detecting an intruder throughout a given space.
These systems may not be practical if you have an indoor pet. Microwave detectors are a very similar type of security alarm that operates under similar principles, but may prove less expensive, since the microwaves can pass through walls and monitor multiple rooms at one time.
5. Window (Shock) Alarms
Shock alarms are used almost exclusively on windows, and work especially well on windows that may be shattered or broken to admit entry into your house. The alarm detects either the sharp sound of breaking glass or the vibrations that accompany broken windows, depending on the type. This option is suitable for windows where magnetic switches will not work.
6. Control Panel Sirens
Control panel alarms are basic sensors that detect if someone is tampering with the panel. Some criminals try to smash or disarm control panels in efforts to gain entry to the house. The sensor, often a magnetic or shock version, picks up on the disturbance and sounds the alarm.
7. Environmental/Detector Alarms
Detector alarms focus more on protecting people from the environment than from burglars. The most common type is the legally required smoke detector, which sounds an alarm in the presence of significant smoke. However, security alarm systems also offer integrated alarms for carbon monoxide detection and advanced smoke detectors with both smoke and heat sensors for better protection. Since these alarms tie into your control panel, they can also send messages to the security company or appropriate organizations if they detect dangerous conditions.
8. Panic Alarms
Panic alarms or “hold up” alarms are a subset of the security alarm sector. They are often installed in a single, easily reached location but may also be portable. Homeowners and others can personally activate them in the case of a burglary or a personal attack. While some activate loud sirens to discourage attack, many send a silent signal for help. This is another popular option for small businesses that may deal with valuable products.
These are the most common security alarm sensors you’ll come across, and all will be helpful in protecting your family and property.