In an electrical installation or an electricity supply system an earthing system or grounding system connects specific parts of that installation with the Earth’s conductive surface for safety and functional purposes. The point of reference is the Earth’s conductive surface, or on ships, the surface of the sea. The choice of earthing system can affect the safety and electromagnetic compatibility of the installation. Regulations for earthing systems vary considerably among countries and among different parts of electrical systems, though many follow the recommendations of the International Electrotechnical Commission which are described below.
This article only concerns grounding for electrical power. Examples of other earthing systems are listed below with links to articles:
To protect a structure from lightning strike, directing the lightning through the earthing system and into the ground rod rather than passing through the structure.
As part of a single-wire earth return power and signal lines, such as were used for low wattage power delivery and for telegraph lines.
In radio, as a ground plane for large monopole antenna.
As ancillary voltage balance for other kinds of radio antennas, such as dipoles.
As the feed-point of a ground dipole antenna for VLF and ELF radio.