Electrical Bonding - Equipotential Bonding

Equipotential Bonding

Equipotential bonding involves joining together metalwork that is or may be earthed so that it is at the same potential (i.e., voltage) everywhere. Such is commonly used under transformer banks by power companies and under large computer installations. Exact rules for electrical installations vary by country, locality, or supplying power company.

Equipotential bonding is done from the Service Panel consumer unit (also known as a fuse box, breaker box, or distribution board) to incoming water and gas services. It is also done in bathrooms where all exposed metal that leaves the bathroom including metal pipes and the earths of electrical circuits must be bonded together to ensure that they are always at the same potential. Isolated metal objects, including metal fittings fed by plastic pipe, are not required to be bonded. European and North American practices differ here; equipotential bonding in bathrooms is not required by North American codes, although it is required around swimming pools.

In Australia and South Africa, a house's earth cables must be connected both to an earthing rod driven into the ground and also to the plumbing or gas pipe.