How to install an electrical change over

To install a change over is pretty easy as you just need to understand the way a changeover is designed. A change over comes into use when you want to be switching between two main source of electricity; for example your main source
and a generator as labelled above. It is also used as a bypass for an electrical appliance in case it is not working.

The cables from the mains will be connected to the short terminals as drawn in the diagram above, if it is a one phase power source you will have to link all the short terminals together.
You should do the same for the generator's side.
The long terminals will be connected directly to the load of the house.
The knob or handle which extends inside the change over is connected to the long terminals.
After you have done this, you are good to go. so when you switch the handle up the load will be supplied with electricity from the mains provided there is supply, when you switch to the middle, there will be no supply to the load, when you switch it down there will be supply from the generator.

To further understand this principle, if you look at the knob that extends inside, you will see that it has some v shaped terminals, those terminals join the short terminals to the long ones in order for electricity to be passed to the load as soon as you switch up or down.