When walking into an electrical outlet wanting to buy a switch, make sure you know what kind of switch you are looking for. Enough have been said about one gang or two gang switch. One mistake that many makes when buying a switch is they did not specify what kind of switch they want and the sales assistant did not get proper clarification from the customer. Most of the time they only realize they bought a switch that is not suitable when the electricians comes and find that they bought the wrong kind of switch.
The most common switches we find in our house are the single pole one way switch and the single pole 2 way switch or 3 way switch. A one way switch is the most common. As the name suggest, it only works one way which means you either switch it “ON” or you switch it “OFF” There are no ways about it.
On the other hand, a two way switch can work both ways. You can switch on the light by throwing the switch in “OFF” position and vice versa. However to make this work, two way switches have to work in pairs. That is to say, you must have 2 individual two way switch to make full use of this ability. This will be another topic that I shall talk about later.
To differentiate a two way switch with a one way switch is easy. Look at the terminals at the back of the switch. A normal one way switch has only to terminals, usually one on top and one at the bottom. A two way switch however, has three terminals, also usually on the top and two at the bottom. This arrangement may vary with different manufacturers, but all two way switches has a minimum of 3 terminals. Again, why is that so will be explained in later postings. There are even some with 4 terminals.
So the next time you need to replace a switch, make sure you get the right one. If the switch you are planning to replace is just for switching the lights ON and OFF with no other functions, you can be sure it is a one way switch.