Single-wire earth return (SWER) or single-wire ground return is a single-wire transmission line which supplies single-phase electric power from an electrical grid to remote areas at lowest cost. The earth is used as the return path for the current, to avoid the need for a second wire to act as a return path.
HVDC SWER power line in Cahora Bassa (Mozambique / South Africa)
In electrical engineering, ground or earth may be a reference point in an electrical circuit from which voltages are measured, a common return path for electric current, or a direct physical connection to the Earth.
A typical earthing electrode (left of gray pipe), consisting of a conductive rod driven into the ground, at a home in Australia. Most electrical codes specify that the insulation on protective earthing conductors must be a distinctive color (or color combination) not used for any other purpose.
Metal water pipe used as grounding electrode
Busbars are used for ground conductors in high-current circuits.
3 ply static dissipative vinyl grounding mat shown at macro scale