What is Earthing and Bonding?
Earthing is the (electrical) connection of conductive parts of an electrical appliance (the exposed metallic bits that can “conduct” electricity!) to the main earth terminal of an installation.
Bonding is the cross-connection of all extraneous metallic parts of an installation (eg water pipes, gas pipes, steel girders etc) in order that all of these conductive parts are substantially the same “potential” (voltage) as the exposed metallic parts of any appliances.
The point of Earthing and Bonding is to prevent injury in the instance of a fault with any electrical appliances or with the electrical wiring. Should a fault occur, electricity will flow along the path of least resistance which could mean it passes to earth through a human. When electricity flows to the ground (earth) it dissipates (mostly in a harmless manner). However if a person comes between the electrical fault (leakage) and the earth, then that person is in danger of electric shock or electrocution.
Normally a modern electrical installation will have an earth terminal, and incorporate earth wires to direct the passage of electricity, harmlessly, to earth. However, whenever a fault occurs, these features can be made redundant. A wiring fault might occur for a number of reasons, including extremes of temperature, moisture, friction or rodent activity. Very often wires and metallic (conductive) pipework are found side by side in a property, which means regular checks of wiring health and modern safety features are vitally important.
Happily this is not the place for a physics lesson, but suffice to say, electricity in metallic objects flows from “lower” to “higher” potential. If you are simultaneoulsy touching two metallic objects (oven and sink), and one of which is “live” through electrical fault, then you are at risk of electrical shock. However if all of the conductive pipework and appliances in the property are earthed and bonded, so as to create a substantially equal potential, then the risk of injury or death is reduced.
Given the age of some houses and their electrical installations, the chances of such fault conditions cannot be overlooked. Regular, periodic inspections are encouraged in order to minimise the risk of injury or death. In fact, so important is the need to maintain earthing and bonding provision, that any electrician you might employ is required by safety regulations to check, and where necessary update, the installation. This applies even if your instructions are for the electrician to work on an entirely different aspect of your property. Be aware!
