A safety ground is a temporary conductor installed to protect electric workers performing maintenance or repairing electrical lines/equipment. Safety grounds are used for two purposes:
- To immediately de-energize a line in the case of accidental energizing of lines or equipment
- To direct current to the ground (rather than through a worker’s body) through a parallel circuit
Line workers may be unexpectedly exposed to energized lines while working for various reasons:
- Switching equipment malfunctions or human errors
- Lightning strikes on the circuit
- Customer generation equipment backfeeding into the circuit
- Induced voltage from adjacent energized lines
- Fault current feedover from adjacent lines
- Accidental contact with adjacent energized lines
The Occupational Safety and Health Administration (OSHA) and the American Society for Testing and Materials (ASTM) have established specifications and proper procedures for installing temporary protective grounds. It is important for line workers to always follow these procedures.
Personal grounds, carried by line workers, are portable devices that temporarily connect a de-energized conductor or pieces of equipment to electrical grounds prior to beginning work. OSHA regulations make it the utilities' responsibility to provide protective grounding equipment that is capable of conducting the maximum fault current that could flow at the point of grounding for the time necessary to clear the fault. It is important for line workers to maintain these grounds in good condition and perform a visual equipment inspection prior to using them. Proper placement and installation of grounds is also important. Failure to use safety grounds properly can result in severe injury or death.