Circuit Breakers
It is an automatically operated electrical switch that is designed to protect an electrical circuit from an overload or a short circuit. Its function is to detect a fault condition that could short circuit or overload the circuit and interrupt the current flow. It can be reset (unlike a fuse) and this can be done either manually or automatically. They are made in various sizes: from a large switchgear that is designed to protect high voltage circuits that supply to a whole city down to a small device that protects household appliances.
Fuses
A fuse is inserted into a circuit to protect the circuit or device from receiving too much current when shorted. When a fuse breaks the circuit, it has to be replaced as it can only be used once. It protects devices and circuits from severe damage from a power surge or other events that cause excessive voltage. It performs this function by interrupting the electrical current through the melting of some of its specifically designed components, and these are melted by the heat generated as a result of the excessive current, thus protecting further damage to the device / circuit.
Double Insulation
Double insulation is an electrical appliance that has been designed in such a way that it does not require a safety connection to electrical earth (the ground). The basic requirement for this is that no single failure can result in dangerous voltage being exposed and being able to cause electrocution. This is achieved by having no earthed metal casing, and is usually achieved by having two insulating materials surrounding live parts. It can also be achieved by using reinforced insulation. The double insulation provides more protection from electrocution because if the inner casing fails, the outer casing will still be protective.
Earthing
Earthing is also know as ‘ground electricity’ as it is a direct physical connection to earth. It provides protection from electric shock for people using electrical appliances. When the wiring in a house is installed, a good conductor is used to connect the fuse box with the Earth. Connections to the ground limit the build-up of static electricity around flammable products or electrostatic–sensitive devices. The earth can also be used as a conductor for telegraph/power pole circuits. In electronic circuit theory a ‘ground’ can absorb unlimited amounts of current without changing its potential. Where a real ground connection has a significant resistance, the approximation of zero potential is no longer valid.
Tamper Resistant Receptacles (TRRs)
They look like ordinary outlets but are designed with spring-loaded receptacle cover plates that close off the slots. The slots only open when there is equal pressure on all 2 (or 3) of the slots. However, when the simultaneous pressure is not applied, the slots remain closed. Thus protecting children from electrocution that is painful and traumatic. Only recently have TRRs started becoming widely used in homes. They have been required in hospital paediatric care facilities for nearly 20 years, and are now installed in new house constructions. In total, they add about $50 to a price of a house being built, and are about $2 per outlet to apply to exiting homes. Despite some special interest groups having objected to these added costs, they are worth the money as they stop the traumatic experience of being electrocuted to children.