[Roverlike]

Among other things, reserve serves on motor starting as more current is drawn from the power network. However, you should have stated what current is drawn at startup on appliance and calculate your power even slightly above that (remember difference in Volts 220-230V).

Fuses are created in standard forms, so you will not have fuse for 62 amps. However you can ask why it is not 80 amps then but 100 amps fuse. When standardisation is done they needed to include power consumed at that time and forseen power that might be taken in next decades. It is not useful to build something which will need to be replaced completly when consumer power rises. It would cost a lot.

Having fuse of 100 amps actualy protects the power network from you this is standard they set up and build network up to that standard. And they will not let you use more power than that.

I can go further in my explanation and set terms like active/useful and reactive/unuseful power. These two powers exist in case current and voltage are not in same phase in case of AC power. Power network needs to be built to sustain both of these powers and that reactive lower actualy represents the reserve you have in case of AC power. But I will not go further and possible start confusing readers.