Light is one of the key elements to a safe home. Entryways must be lighted to welcome visitors and reassure homeowners who would answer the door. Walkways, grounds, exterior doorways, and garages need light for safety and security. Hallways, bathrooms, and stairs are all safer when lighted at night. Using sensors and timers helps owners respond to these needs for home security and safety.
A sensor is a device that receives and responds to a signal or stimulus. A photosensor is a light-detecting device that operates a luminaire or light fixture when the surrounding light level drops. Photosensors are often used for exterior and perimeter lighting where they maintain light levels throughout the night and shut off during the daylight hours, providing a great deterrent to would-be intruders who are put off by the presence of light.
Photosensors can be used for interior fixtures, too, particularly in hallways and lobbies where nighttime entry and exit is made more secure. Photosensors range from the simple plug-in variety that is commonly used for nightlights, to the automatic exterior lighting commonly found along walkways.
Motion detectors, or occupancy sensors, turn lamps on automatically when motion is detected. They can be applied both inside and outside, and there are two primary types: infrared and ultrasonic. Infrared sensors respond to a change in infrared heat in a space, such as when a new body enters the room. Ultrasonic sensors engage when they detect a change in ultrasonic frequencies caused by motion in a space.
Both types of sensors are mounted and wired like wall switches, and are available with a number of options, like dimming, manual on/off, and three-way switching. They can even extend the service life of your lamps by extinguishing the lights when a room is unoccupied. For outside use, you should consider a combination motion detector and photosensor, which will make lights come on when motion is detected, as well as when the surrounding light levels fall below a preset such as sundown.
Because sensors respond to stimuli, they have many applications in home safety and security. Since sensors are programmed to detect and respond, they are frequently linked to alarm systems. Perhaps the most well known sensor-alarm combination is the smoke alarm. Here the smoke acts as a stimulus, triggering the sensor, which activates the alarm. The same principle directs sensors that detect intrusion, carbon monoxide, moisture, wind, power outages, high water, and even the sound signature of a tornado. Any or all of these can be programmed as part of a total home security package. In your car, sensors can even help you park without hitting the other car in the garage!
Timers are dependent on electricity to help them maintain the clock that drives their mechanism. By definition, timers are designed to turn the lights on and off at prescribed intervals. Their timing may be automatic, as in the case of spring-winding interval timers that power heat lamps or lights in restrooms and hallways. These timers can be very handy in bathrooms where lights are left on or where timed ventilation is needed.
Plug-located timers are common, inexpensive security measures. These units feature a clock that is set for on-off times, plugged directly into the wall socket, and used as the plug-in device for lamps, stereos, or televisions. Socket-located timers fit directly into the medium-base socket of an incandescent lamp. This timer will activate when the lamp is turned on and will automatically turn off after the designated time has elapsed. These timers are very inexpensive and easy to install, but make sure to follow the installation instructions if you do it yourself.