Let's talk Engineering PT3! How would you connect a load with more than one switches in an AC circuit?

See my sketch. How would you do yours?

After establishing in our previous post that it is safer to connect switches on the positive terminal of an AC supply, we want to discuss how to connect and operate more than one switch to control a bulb.

The pictures above are the line diagrams of the connection of one, two and three way switches. Following this pattern, as many switches as needed can be connected to operate one bulb. More than one switch is connected to a load so that the load can be operated from any of the switches.

The switches must create a complete circuit for current to flow and the bulb to light. When any or all of the switches are on, the circuit is complete. If any switch is on others are off, you must need to open the circuit from the switch that is on to put off the bulb. You can put on the bulb from any switch as long as all the switches are off. You can turn the switch on and off from any switch only if the switch is an electromagnetic switch.

Electromagnetic switches are not like the conventional mechanical switches we see around us, they are relays that become temporary magnet when electricity flows through them creating a contact between the electric supply and load. They act like sensors because they complete a forward and backward action. when they are triggered, they create an action (on) and return to former position; when triggered again, they create an action and return to former position (off). That is why if an electromagnetic switch is used in connecting more than one way switches, they can be operated from any of the switches.

In our next article, we will discuss another way to connect more than one way switches in an AC circuit.