IGGY,
Like Chuck I use the PSX-AC for all my circuit protection as well as having TVSs installed. Not only is it an excellent electronic circuit breaker, but it performs several other functions such as an alarm and LEDs let you know of a short, manual or automatic reset, track power on, plus others. However, this makes the PSX a bit expensive.
For a less expensive full protection option, LOU1985's setup works well but you have to replace the fuse every time you have a short. Some folks use other types of circuit breakers but if you want the best protection using a fast blow fuse (or a PSX) is best.
Here is a simple diagram using the TMCC handheld for command and the ZW's handles for conventional.
The TVS actually provides better protection for your engine's electronics than a CB or fuse. Many on the forum say only one TVS, at the transformer, is needed. Since a TVS can fail without you knowing it, I like multiple TVSs as backup, one at the transformer and one at each track connection. There is some thought that placing the TVS as close to the engine as possible is better, and actually inside the engine is best. TVSs are cheap so get a bunch.
