Pete is right here - take care with high current outputs! Always install some sort of a current limiter - this can be a elaborate electronic contraption or even a simple fuse.
It is mainly the current (Amperes) which is responsible for heating up a wire. If you install bus connections under the layout which carry high currents, be sure to use very heavy gauge wire. In case of a short somewhere thin wires quickly are heating up...
You don't want your house go up in flames, do you?
BTW- the same holds true for trickle charged car batteries as a power source. These things can deliver currents up to more than 200 Amperes. (That's a normal peak current when you are starting your car.)
Long time ago, when I looked for more power for a slot racing layout, I installed such a power source. Accidentally I touched both poles with a small screwdriver - the metal was vaporized instantly and I had quite nasty burns on my fingers!
ops: (Still have the scars.) That's why for my model RR room, car batteries are a definite no-no!
Ron