Tech Talk

Ground Loops

Ground loop formation is a common problem in today’s electronic equipment installation where multiple devices and peripherals are connected to different power sources communicating through data lines or audio/video wiring.

What is Ground Loop?

According to the Telecommunications Industry Association (TIA), "Ground loop in an electrical system is an unwanted current that flows in a conductor connecting two points that are nominally at the same potential, i.e., ground, but are actually at different potentials".*

Ground loops occur when two or more devices are connected to a common ground though multiple paths. Ground loops mostly form in networked equipment and peripherals, where systems are connected to the earth ground through different sources and communicating through the data line. When there is a difference in the ground voltage references, current flows through a circular path from a reference ground point to the other ground sources through the data line. This causes the formation of a ground loop which can cause hardware damage or create noise and interruption to  networked systems.

This concept also explains how ground loops are created in audio/video systems which cause consistent humming or equipment failure when they are connected through shielded wiring.

THE GROUND LOOP

One of the most common effects of ground loops are intermittent lockups of computer or point of sale (POS) systems. It often occurs when a networked system and it's peripherals are plugged into different electrical circuits/outlets, especially in older buildings or facilitieswith ground wiring problems.

Ground loops are usually not predictable and problems typically arise after the equipment is installed. In this scenario, the equipment malfunction is either blamed on the installer or the equipment manufacturer but neither is the actual culprit. Many factors can cause formation of the ground loops but most often it is a facility issue due to old or improper electrical wiring in the building.

Smart Power Systems “Smart Ground” patented technology eliminates the ground loop current noise that are common in networked systems as well as the audio/video installations. To completely protect microprocessor-based equipment from ground loop problems ensure that all the networked equipment and peripherals are properly protected by a transformer based filter equipped with the Smart Ground circuitry. 

Footnotes:
* Source: Telecommunications Industry Association (TIA)
**Source: Computer Desktop Encyclopedia