It is a switch that provides a simple connect or disconnect capability across two terminals. Provide 120 volts 15 20 amps and have one hot wire and one neutral wire.

Magnetic Circuit Breakers A Series Double Pole Single Throw
Single pole vs double pole. The difference between a single and double pole switch is that the latter controls two circuits at the same time. Traditional plate grid plate and switches. The other option is a double pole thermostat. Well take a closer look at the differences between each of these breakers and discuss when you should use one over the other. No batteries no power stealing. A single pole switch usually refers to a single pole single throw switch spst.
Provide 240 volts 20 60 amps and have two hot wires that share one neutral wire. A more complex setup 4 wires are required allow for the power to be switched off completely. That way if either hot leg draws too much current both breakers will trip simultaneously effectively stopping all voltage to the appliance. Flat plate grid plates and switches. Double pole circuit breakers are used in this case which consist of two single circuit breakers whose trip handles are physically tied together. It is commonly used for onoff applications such as light switches.
A double pole switch is what you need to control a 240 volt device because 240 volt circuits have two hot wires. Unlike the single pole setup the power supply of a double pole isnt directly tied to the heater its powered by a separate circuit. A double pole double throw dpdt knife switch.