• never work on a circuit with current on.
Turn off at mains and isolate circuit by removing relevant fuse. Keep this with you until you restore supply
• never touch plugs and sockets with wet hands
• remove plugs from socket when working on appliance
• always use the correct fuse wire when mending a fuse
The importance of earthing
Earthing is an essential safety feature of all wiring systems. To complete a circuit, electricity either flows down the neutral conductor of the supply cable or it flows to earth. That is why you get a shock if you touch a live wire.
The idea of earthing is to connect all metal fittings and appliances in the house with a good conductor – the ‘earth wire’ in cables and flexes. If a fault occurs that makes this metal live,the presence of the earth wire prevents the voltage from rising much above earth voltage.
At the same time, the fault greatly ; increases the current being drawn to the metal via the supply conductor, and this current surge is detected by the circuit fuse, which ‘blows’ and cuts off the current flow. The earth conductor links socket outlets and appliances (via their plugs) and is connected to a main earthing terminal at the house fuse box or consumer unit. This is usually connected to the outer metal sheath of the underground supply cable. All metal pipework in the house is also earthed by being connected to the earth terminal – this is called ‘cross bonding’.
Old wiring
Some old installations may still be using lead-sheathed or tough rubber-sheathed (TRS) wiring, with the conducting wires insulated in vulcanized rubber, or vulcanized rubber insulated, taped and braided
The right connection
The plug is the vital link between any electrical appliance and the mains and must be connected up correctly if it is to do its job properly. With flex in the new colour codes, connect the BRown core to the Bottom Right terminal, the BLue core to the Bottom Left one and the green-and-yellow core (if present) to the top terminal. With cores in old colour codes, Red goes to the bottom Right terminal, BLack to Bottom Left and green to top.
Old colour codes – Before the introduction of new international colour codes, flex used red insulation to denote the live conductor, black for the neutral and green for the earth.
Warning: Electricity is dangerous.
In some European countries, regulations stipulate that all home electrical work must be carried out by a qualified electrician. These insulating materials deteriorate with age (about 25-30 years) so the wiring can become dangerous. Therefore it really does need to be replaced with modern PVC-sheathed and insulated cable.