Isolated ground
An isolated ground (IG) is a local ground connection used with a supply, one of the common earthing arrangements used with domestic mains supplies.
The primary reason for the use of isolated grounds (IG) is to provide a noise-free ground return, separate from the equipment grounding (EG) return. The EG circuit includes all of the metal conduit, outlet boxes, and metal enclosures that contain the wiring and must be grounded to provide a safe return path in case of fault currents. The IG provides an insulated, separate ground path for the ground reference in electronic equipment, such as computers, hospital equipment, and audio equipment. IG does not break ground loops, which can damage equipment like computers, printers, etc.. Interconnected computer equipment often benefits from single-point grounding. IG is only used with special equipment that require it. The IG is typically insulated and separate all the way back to the point of earth grounding rod out side of the building. The IG is NOT connected neutral or any other. Due to the installation of a separate, insulated conductor and the associated special outlets required, IG circuits are more expensive to install than standard power circuits.