A cable that can generate an AC current. This is frequently generated by separate electrical sources feeding different components of the system, resulting in variable earth potentials at each end. The result is signal interference, which appears as dark bands across the monitor and, on rare occasions, tearing in the top third of the image.

A ground loop is a system-grounding issue that happens when one device in a system is linked to a different electrical ground than the other devices' ground. The ground difference can be detected at low voltages as low as 200mV.

Read More: What is the difference between simplex and duplex multiplexers?