Earthing and bonding minimise the dangers arising from:
- Faults between electrically live conductors and non-current-carrying metal work.
- Atmospheric discharges (lightning).
- Accumulations of electrostatic charge.
Earthing is achieved by the establishment of an electrically continuous low resistance path between a conducting body and the general mass of the earth.
Earthing may occur inherently through intimate contact with the ground or water, or it may be provided deliberately by means of an electrical connection between the body and the ground.
Bonding may be effected between two or more bodies without involving earthing, but more commonly earthing gives rise to bonding with the general mass of the earth acting as the electrical connection.
Bonding may arise by construction through the bolting together of metallic bodies, thus affording electrical continuity, or may be effected by the provision of an additional bonding conductor between them.
Most earthing and bonding devices intended to protect against electrical faults or lightning are permanently installed parts of the equipment which they protect, and their characteristics must conform to the national standards in the country concerned or to classification societies’ rules, where relevant.Earthing and bonding to guard against static electricity are often associated with movable equipment and must be established whenever the equipment is set up.