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.
The electrician has sealed the hole around the electrode. The acorn clamp and the #4 AWG grounding wire coming from the panel have been connected to the rebar electrode. In addition, a mud ring has been installed in front of the clamp in order to provide an inspection access after the drywall is installed. Note the paper label attached to the rebar electrode.