The portion of a circuit that is connected to a buried metallic object such as a grounding rod or water pipe.

Passage through an opening in the exit direction, especially passage that leads out of a structure.

A door unlocking device that is installed in the door jamb and that works in conjunction with a mechanical lock or latch mechanism.

A mechanical locking device that has been modified to allow an electric circuit to lock or unlock it.

A device that locks/unlocks an opening without moving parts, using pure electro-magnetic attraction.

To apply power.

A report of an action that takes place within the system, such as a door being opened, a person going through a portal, a time zone being active or the security system being armed.