Why is correct equipment important in three phase?

Answer for USA, Canada and countries running a 60 Hertz supply service.

In commercial and industrial installations it is important to have the whole building phased correctly. Usually these types of businesses are three phase. Three phase motors that have plugs on them for quick swapping in case of a break down can be connected anywhere in the plant and still have the correct rotation. Also if the business has a stand by generator it also has to be correctly phased with the plant so as not to reverse three phase equipment when the generator starts. Phase sequence from left to right is A, B, C.

I'm not an electrician but i do know that in some motors if any of the positive wires are swapped from there correct place the motor will run backwards (in the wrong direction) it is important to know the correct sequence.