Safety
Above or below the meter dials is a row or circuit-breakers or fuses. These act as safety devices. If too much electric current is flowing along a wire, friction between electrons can cause overheating and a fire could result. The wire inside the fireproof fuse-holder acts as the weak point in the circuit. If too much electricity is flowing the fuse will melt (blow) and the circuit will be broken. Circuit-breakers magnetically detect an overload of electric current and automatically switch off the circuit.
Power points have switches and three-pin sockets. A circuit is completed when the pins of a plug are inserted in the socket and the power point and appliance are switched on. Two of the pins (the active and the neutral) are connected to the current carrying wires. The third pin is connected to the earth wire. This acts as a safety device and is connected to the metal frame of an appliance. If a loose wire causes the frame to become live a large current will flow through the earth wire, via a connection to the ground, and blow the circuit fuse or trip the circuit breaker. Some appliances have a special double insulation. Their plugs only need two pins - an active and a neutral.
Electricity is a vital part of our modern world. It powers a wide array of devices that enhance and enrich our lives.
 |