Publisher Summary This chapter explains the concept of earthing and bonding. Correct “earthing” is a primary requirement for general electrical safety, reducing the risks to both human life and installations. The relevance to explosion protection is covered thoroughly from the explosion point of view with some initial general discussion to ensure that the intentions of the earthing philosophy are fully understood. The principles of electrical earthing are agreed upon internationally, though there are differences as to how these principles are best achieved in practice. Structural or fault currents arising from electrical equipments operating in hazardous areas must not become a source of heat or sparks. Equipments must be adequately earthed to ensure that connections are of high integrity and low impedance. This must be adequately maintained throughout the life of the installation and equipment. There is a subtle but essential difference between earthing and bonding, which must be understood. Earthing is where a low-impedance path is provided in order to allow return currents to operate electrical protection devices such as fuses and overcurrent trips in an appropriately short time. Bonding is where voltage differences between electrical conducting parts are eliminated. The bonding of all the cases to the structure and the structure to the SPNE forms the bonding paths. Static electrical charge is caused by the forced separation of molecules of non conducting materials. Movement of the material or friction against the material can cause the charging effect.