Which type of switch allows control over two separate circuits with a single action?

The type of switch that allows control over two separate circuits with a single action is the double pole single throw switch. This switch has two sets of contacts which can be operated simultaneously by a single actuator. When the switch is toggled, it connects both circuits to either an "on" or "off" position depending on its design.

This functionality is useful in applications where two circuits need to be controlled together, allowing for simple and efficient control without needing to operate multiple switches individually. This is particularly beneficial in situations like lighting control systems, where you might want to turn on two different lights from a single point.

The single pole single throw switch only controls one circuit, thus it doesn't achieve the desired dual control. Similarly, while the double pole double throw switch is capable of controlling two circuits, it allows for multiple states (on/off for two different positions), rather than just a simple on/off control that the double pole single throw switch provides. A micro switch, on the other hand, is a specific type of switch best suited for low loads and does not typically operate two circuits simultaneously in the way the double pole single throw does.