When wiring and setting up a machine or other electrical equipment, ground loops can be unintentionally created between connected electronic devices. High current flowing through these ground loops can cause sensitive electronics to malfunction or fail.

Understanding Ground Loops

A ground loop occurs when multiple pieces of electrical equipment that are connected together are also connected to ground at more than one point.

Differences in cable length, resistance, and current paths can create voltage potential differences between grounding points.
 

Even a small potential difference of 1–2 V can cause large currents to flow between devices, which can severely damage electronic components.

A video link below provides a clear explanation of ground loops and how they can be prevented.

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

Examples of Damage Caused by Ground Loops

The images below show burnt components caused by a ground loop on a MASSO G3 Touch controller.

Preventing Ground Loops

On a machine with multiple electronic devices and long cables, ground loops can form in many ways. Common examples include:

• Ground connections between the controller and motor drives

• Ground path through a VGA cable between the controller and monitor

• Ground connection through an externally powered USB hub

  • Note: If the USB hub is powered only from the controller’s USB port, a ground loop is not formed

• Long USB cables where the USB connector shell contacts another grounded surface, such as the machine frame

• The controller ground pin being connected to the machine frame

  • This can occur on the MASSO G3 Touch via the rear mounting plate

Best Practice

The most effective way to avoid ground loops is to ensure the entire machine is grounded at a single point only.

This single-point grounding approach should apply to:

• The machine frame

• The controller

• Motor drives

• Peripheral devices

Ground loops can form in many ways and are difficult to document exhaustively. However, understanding how they occur will help with correct machine wiring, fault prevention, and effective troubleshooting.