Earthing Electrical Circuits
Introduction
The ground we stand on is a much better conductor of electricity than the copper wires in our domestic circuitry and electricity will always travel via the shortest and fastest route through any set of connected conductors.
Therefore, if you touch a live electric source, the current will flow through you to the earth, potentially causing a massive electric shock and even death.
Earthing domestic circuits
To prevent damage caused by overheating, electrical appliances and metal items in a home such as pipes, radiators, sinks, baths and basins are ‘earthed’. This means that a dedicated earth wire permanently connects each of these items to a metal earthing block in the consumer unit.
In the event of an electrical fault, current is carried safely away to earth and the change in the electrical flow will cause the fuse or circuit breaker to blow.
In the case of electrical appliances, the earth wire in the flex is covered in yellow and green plastic, and should be connected to the earth terminal of the plug or switch.
In cabling and circuitry, the earth wire is an unsheathed copper wire included in the flex between the neutral and live wires.
The only exception to this is where the appliance is double insulated. This means no earth wire is required or should be connected. Double insulated appliances carry the symbol shown left.
Earthing domestic plumbing
Sinks, basins, radiators and pipework should be earthed using an earth clamp and terminal connected via a yellow and green earth wire. When attaching the clamp to a pipe, ensure that it makes a good connection by removing any paint or corrosion first. If plastic connections have been used on pipework, the earth connection must be restored across them.
To earth mains water and gas pipes, 10mm˛ green and yellow single-core earth wire should be used to clamp the wires within 600mm (24in) of the meter or stopcock.
To earth metallic sinks, basins, baths and shower trays, 4mm˛ single-core earth wire should be used.
In cabling and circuitry, the earth wire is an unsheathed copper wire included in the flex between the neutral and live wires.
Further information and useful links
- Find an Electrician near you
- Find Electrical Inspection & Testing Services near you
- Find an Electrical Merchants near you
- IEE Regulations
- Part P Competent Person Scheme
- National Inspection Council for Electrical Insulation Contracting
Site Pages
Featured Articles