In some installations of vehicle video camera systems, the customer requires or desires to monitor an activation device in the vehicle.

In a Police Patrol Wagon, Suspect, Prisoner & Inmate in-Custody Transport Camera application, the camera can be placed at the rear loading and unloading door of the prison bus. They need to document when and how many times that door is opened to ensure inmates are not getting out of the vehicle on their own.

In a Medicaid Medical Transport (NEMT) In-Vehicle Surveillance Camera-equipped vehicle, they may need to document the pickup time, drop-off time, and locations (passive GPS) to prove the passengers were transported to their proper destinations. In some cases, they may have wheelchair lifts that can be documented as used by the event marker or indicators.

The most frequent use of the event wiring is to document the extension of the stop arm, the Red stop Lights in the School Bus Stop Arm Cameras:

The photo shows a close-up of event connections before they are taped and tied to the power harness.