Electrical switch is a device used to
complete or deactivate an electric circuit. Its main function is to
regulate the flow of electricity in any circuit. It works as per two
modes; 'on' and 'off'.
When the switch remains in the “off” mode, it brings a halt to the functioning of circuit while it voluntarily activates a circuit, the moment it goes to “on” mode. An electrical switch has two most important parts; an actuator and two contacts. An actuator is the moving part of a switch. It is the movement of the actuator that controls the circuit providing force to the contacts. It can be found in many types. The most prominent ones are ; push button, rocker, toggle, dial etc.
The toggle is called as dolly also. These actuators share, by their movement, the same common goal to ensure electric supply to the related circuits to run various electrical mechanism.
Contacts are made of any two pieces of corrosion free metals. In order to complete the flow of power to activate a circuit, they touch while their detachment causes the disconnection in the circuit. It results in the inaction of the electrical device it is attached to.
There are many types of switches. However, only four types; single pole, double pole, three way and four way are very prominent and used extensively. The defining features which differentiate these four types from each other are many. They can be such as; whether the switch has “on” and ”off” mark it, the number of locations it can be operated from, the number of terminals used etc.
Single Pole Switches: These switches, unlike three or four way switches, have always “on” and ”off” written or engraved on them. They can be operated from a single location to run any electrical device. Any single pole switch has two terminals. One is used to bring the electricity “into” the switch while the other one is used to send back the same electricity to any appliance or a light bulb etc.
Double Pole Switches: Unlike single pole switches, the double pole switches use four terminals in number. However, they too have the markings denoting “on” and “off” written on them. These four terminals enable a double pole switch to run 240 volts circuits. Also, they can be operated from a single location.
Three Way Switches: These three way switches, unlike first two types, have no markings of “on” and “off” pasted on them. Interestingly, these switches can be operated from two different locations. Hence, they are always used in pairs. These are basically used in three way applications. These switches have three terminal screws. The first one is called “common” while the last two's are called “travelers”.
Four Way Switches: These switches borrow some attributes with double pole switches and three way switches both. Unlike the double pole switches, they don't posses “on” and “off” markings, but they look almost like them.
These switches are used to control electrical devices from as many as three different locations. They always work as connectors between two three way switches. These switches have four terminals with no terminal being termed as “common” one.
Apart from these four major types, there are many other types of switches also. According to their function and mechanism, they have been given various interesting names, such as; hall-effect switch, membrane switch, time switch, centrifugal switch etc.