Most storage devices that do not require vision and a brain to read data fall into this category. Electromagnetic data may be stored in either an analog data or digital data format on a variety of media.
Direct Tripwire Alarm - The wire placed across the path is directly connected with the cord, wire or string placed across the particular path. Laser Tripwire Alarm - An invisible laser, typically an infra-red, is used instead of a cord or string.
1 Prewired conduit, or armored cable, offers an all-in-one solution with the wires already running through it. 2  Metal electrical boxes must be used with metal conduit.  Running a green grounding wire is recommended, though code may allow the metal conduit itself to serve as grounding conductor.