Ground Loops

While wiring and setting up a machine or any electrical equipment, grounding loops can be formed between different electronic devices, and the high current flowing through the grounding loops can cause sensitive electronic equipment to malfunction or fail.

WARNING: Ground loops can cause equipment malfunction and damage if the ground loop potential difference is too high.

Understanding ground loops

A ground loop is formed when multiple parts of electrical equipment that are connected together are connected to the ground at multiple locations. The distance and resistance in the current flow from the grounding point can cause these differences in potential. Even a small potential difference of 1v to 2v can cause high amounts of current to flow between the equipment which can severely damage components on equipment.

The below is a great video explaining ground loops and how they can be prevented.

Examples of damage caused by ground loops


Preventing ground loops

On any machine setup, multiple ground loops can happen where long cables are connecting equipment. Some examples:

  • Ground wires between controller and motor drives.
  • VGA screen ground wire between controller and VGA monitor.
  • Ground wire between external powered USB HUB. NOTE: If the USB HUB is only powered by the controller's USB port then a ground loop is not formed.
  • If a long USB cable is used from the controller and the other side of the USB socket's body touches another ground such as the body of a machine.
  • If the controller's ground pin is connected to the frame of the machine. This is can happen on the MASSO G3 Touch controller via the rear mounting plate.

The best way to avoid ground loops is to make sure that the entire machine is only grounded at one point only. The same applies to when wiring the machine frame and other electronics. Ground loops can be formed in a lot of different ways and are hard to document but having this understanding can help plan the wiring of machines and troubleshooting.