Need Some Electrical Expertice

[nachoman]

BiL:
I don't think you can "step down" 10 amps. You can put a fuse in the circuit but you can still get the 10 amps until it blows. Even dividing it up between 2 throttles, if one only needs 2 amps the other one could pass the other 8.
(Someone else may have better experience of this than I do.)

think of it like your house - you likely have a 150 amp or greater main breaker, and 15 or 20 amp breakers for most of the rest of the circuits. potentially, 150 amps could be supplied to your house at any given time, but more than likely it is less than that. But, you don't want 150 amps running through any given circuit, because if there is a short somewhere, it will fry the wiring in your house or in whatever appliance has the short circuit. So, they divide the 150 amps into smaller circuits with smaller breakers. A 14 gauge wire can easily handle 15 amps, but is TOAST at 150 amps. For your model railroad, you could do the same thing - divide the 10 amps into two 5 amp circuits protected by fuses. Or, you could have only one circuit with a 5 amp fuse, and the other 5 amp capacity is unused. Basically, if there is a short circuit, it will use whatever amount of current is available until something burns up.