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 The basic arrangement in a switch is a closed or open circuit. When a circuit is closed then the electrical flow will continue from one point to the next http://en.wikipedia.org/wiki/Electrical_circuit.
When the circuit is open the flow is interrupted and the circuit does not complete. The contact points are designed to allow the flow of current to proceed so are made of a conductible material such as metal. When the contact points are not connecting there is an air space, which does not allow the flow of power to continue.
The switch circuit can be in two normal states. It can be a ‘n.o’ switch which means that the contacts are normally open so in a non circuit completion state. The reverse is also viable in a ‘n.c.’ switch where the contacts are normally closed and a continual flow of power through the circuit is the resting state.
The method in which the contacts vary with different types of switches depends on the type of switch. A pole set of contacts will apply to a single circuit switch whereas a throw set of contacts would usually have two or more positions for the switch to be in other than when the switch is not completed. In multi-throw switches there are also options in the order of procession of the switch current. Make-before-break contact systems the new contacts are flicked on before the previous ones are turned off. A break-before-make system will do the opposite where the first set of contacts is broken before the new set of contacts is turned on.
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