There is always a limitation of availablity of power in all homes and buildings. You cannot draw more than a preset amount of power from the supply lines. If you do, a fuse will blow, and you will need to get the engineers to come to your place to fix the fuse. So if you are throwing an extravagant party, where you will be putting up a lot of lights and music and stuff, the power that comes in the mains might not be sufficient. And for the extra power, it is not easy to get any sanction from the power department, and for a one night’s stand, generators should be all that is needed to help you out.