[ksafin]

Originally Posted by yash101

When talking big power like this, less is better
30 Amps means that less current (hoh flowing through the pipe) is flowing than the 40 amps, or greater current.

That means that:
A) Motor Controllers Cooler
B) Fuses trip easier
C) You can use thinner wires
D) You fuse is smaller
E) You will ask yourself why a motor suddenly shuts down at ~75% power!

I think "less is better" isn't accurate.

Using a 30 amp fuse does not mean "less current" flowing. It just means that once the current draw reaches 30 amps, it'll pop, instead of at 40. That is to say, fuse doesn't determine current.. a victor in identical conditions will draw X current in both the 30 amp and 40 amp fuse, but will not draw > 30 amps in the 30 amp fuse.

Motor controllers cooler - not really. Again, this is dependent on the stress involved. They'll only be cooler by the consequence of stopping due to a fuse pop.

Fuse trips easier - no bueno.

Thinner wires - more resistance, meaning hotter wires. For most motor applications you can end up pulling quite a bit of current which in extreme cases could even melt your wires.