Wiring question: house current to transformer

[rrinker]

Fuse belongs on the hot side. As does the switch. With a polarized plug and assumign the house wiring is done correctly, there really shouldn;t be any voltage between ground and neutral (but don't try this out by touching it!). That's one of the things the "wiring fault" light on a surge protector or UPS detects. Or better yet get one of those little testers witht he three LEDs and plug it in, it will tell you if the wiring from the outlet back to the box is right or if someone flipped the hot and neutral or the ground is bad.
Don;t rely on the house breaker, fuse the input to the transformer. A fault could develop in the primary that draws 10 amps - it won;t trip the 15 amp breaker but that little transformer will have 1200 watts cooking through it - plenty to set things on fire.

--Randy