Parallel Switch Circuit

Switches in Parallel If several on-off switches are connected in parallel only one needs to be closed (on) to complete the circuit. The diagram shows a simple circuit with two switches connected in parallel to control a lamp. Switch S1 OR Switch S2 (or both of them) must be closed to light the lamp.

What happens if a switch is open in a parallel circuit?

If, on the other hand, the open occurs in a parallel path, some current will still flow in the circuit. The parallel branch where the open occurs will be effectively disabled, total resistance of the circuit will increase, and total current will decrease.