Earthing System Design

The value of the computer equipment, television equipment, telephone equipment and electrical system within a house is now measured in the thousands of pounds so it makes sense to protect it. Insurance is the obvious protection, there is however another type of protection that is required, surge protection, either from the electrical system that supplies the house or lightning strike. An earthing system should be seriously considered to protect against lightning strikes.

AV equipment requires a special type of earthing to give a minimum impedance at high frequency this is achieved by using earthing cables for that equipment that are of the appropriate type suitably sized.

To protect against 'mains' bourne surges the consumer unit should be equipped with a proprietry surge arrester with replaceable cartridges.

The earthing system should consist of interconnected earth rods, a main earth bar and surge arresters connected to each external telephone line, every aerial amplifier input and the consumer unit surge arrester and a connection to the aerial support metalwork, the satellite dish and the electrical service head earth point.

This is in addition to the normal earthing and bonding within a house where all metal pipework must be electrically bonded, with the water and gas services being bonded to the service head earth point.