Troubleshooting

What is a Ground Loop?

Ground loops can be detrimental to the intended operation of the electrical system.  The question arises:  What is a ground loop?

Ground Loops generally occur when there is a difference in potential between the various grounding points.  This usually happens by plugging a device in your system onto a different ground.  

This diagram shows three devices (Computer, Distribution Amplifier, and Projector).  The Computer and Amplifier are plugged into one ground, while the projector is plugged into another.  This is a potential ground loop.

When this occurs, 60HZ ground currents and high frequency noise can flow around the system.  This can cause a hum in both audio and video signals.

Audio hum is the most obvious evidence of 60HZ ground loop currents as one can hear it directly from the speakers. Video hum can be more mysterious. It usually manifests itself as a series of faint lines that rise up through the video image. Sometimes they are very faint but, occasionally, can be quite severe.

How do you get rid of a Ground Loop?

Get all equipment on the same ground.  This may be as simple as plugging a piece of equipment into another power outlet.  It may require an electrician to make changes to your electrical system.  There are several methods an electrician can use to fix a Ground Loop.