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How to identify and address Video Ground Loop Interference 

When a user is seeing lines on their monitor screen, it is usually caused by Video Ground Loop Interference. When a Ground Loop problem occurs, you can see a horizontal line or band (also known as hum bar) across the monitor that slowly moves up the screen. This interference can sometimes be barely noticeable or severe enough that the image is fully distorted. If the camera is Line-Locked, the lines or band will still appear but may stand still.


Video Ground Loop Interference can be caused by many different factors such as:

  • Interference with the power cable

  • Different ground voltage potential between camera ground and monitor/DVR ground   

  • Cameras installed on a metal building

Solutions:

Video Ground Loop can be resolved in different ways.

  • A Ground Loop Isolator can be used to isolate the rolling lines or bars on the video output.

    Ground Loop Isolator should be installed at the camera end by connecting the BNC connector of the Isolator to the camera and the BNC Male connector of the coax cable to the BNC Female connector of the Isolator. In a multi-lcamera installation, it is recommended that a Ground Loop Isolator be installed for each camera.

     

    VIDGL (or) UTPGL is available from our accessory line:

    vidglutpglpng

  • If the Ground Loop Interference is caused by using 24VAC power supply, sometimes reversing the power connections to the camera will eliminate the interference. This will not work on cameras using 12VDC power input.

  • Make sure the BNC video cable is run away from the power lines if possible.

  • If the camera is installed on a metal building, sometimes placing an insulator between the camera and wall will eliminate the interference. Examples of insulators are wood, plastic and rubber.  All of our new cameras now come with a mounting plate with foam gasket for ground loop isolation.  

    camerainstall
Initial Publish Date: April 7th, 2025

Transcribed by: Tyler Rowe, Customer Service