Mostly, this is not a proffered method to wire single way switches in series as parallel or series-parallel connection is used in common electrical wiring installation. In some case, it may seems useless connection, but there are some possibilities where we have to control single load from two places while both switches must be switch ON to operate the load.

Before go in details, we will see the basic construction and operating mechanism of single way switch which is shown in fig below:


Below is a simple step by step tutorial with schematic and wiring diagram which shows how to wire single way switches in series ?


Requirements

  • Single Way Switches (SPST = Single Pole Single Through) x 2 No
  • Lamp (Light Bulb) x 1 No
  • Short pieces of cables x 4 No
Procedure:

Connect the two single way switches, light bulb in series to the power supply as shown in fig below. Keep in mind that both switches S1 and S2 must be closed to complete the circuit.

If there are more switches connected in series with electrical appliance i.e. light point, all of them must be at ON position to operate the load. If one of the single switch is open, the circuit won’t work then.


How To Wire Switches In Series?
The circuit will only complete if both of the switches are at ON position. In other words, If one of the switch are open or at OFF position, the light bulb will not glow. This is the same case for other loads as well which are connected in series to control by two single way switches.

Below are the different positions of single way switches and light point when connected in series.



Switches in Series Different Positions of Switches & Light Bulb

To get the switching position in ON condition for light bulb, the above operation is same as the Digital Logic AND Gate  truth table which is given below.


In simple words, there are four switching positions and if both the switches are at ON position, the light bulb will glow. On the other hand, if one of the switch is at OFF position, the current will not flow in the circuit as the circuit behaves like an open circuit, hence bulb will not glow. No matter all of other connected switches are at OFF or ON positions.