Amp. of fuse needed?

I assume you are running conventional.  The fuses should be on the A/B/C/D outputs.  For the PW ZWs probably 7 amp fuses would be good enough for each output.  There are fast acting circuit breakers that work just as well, but the initial cost is much higher.  The trade off is not having to replace fuses all the time.

Another requirement for command control engines is protection from voltage spikes using TVS diodes.  These are cheap and it is recommended you use a couple of them in line to the track because TVSs have a failure mode that is not detectable. Below is a possible way to set this up.

All my ZW and TIU outputs (hot sides) use P&B thermal circuit breakers. They cost $5 each and I consider them to have saved me thousands of dollars over the years in otherwise blown electronics.  They are available from Mouser or Digi-Key. Model W28-XQ1A-5 (5 amps) , W28-XQ1A-6 (6 amps), or W28-XQ1A-7 (7 amps). I personally use the 5 amp breakers but folks running multiple engines on the same track may want to go as high as 7 amps.

Many thanks to CARRilot & Mr. Brown, the info is great.  As I stated I haven't had an issue as of yet , but I will do this upgrade ASAP before pressing my luck.

Thanks again,

Old Chuck

I use 10 amp mini fuses and TVS diodes on the track circuits as well as Eaton FAZ-B breakers.  Breakers are 3, 4 or 5 amp depending on the track.  The breakers almost always beat the fuses.  I use smaller fuses on accessory circuits that have higher gauge wire.  If you just use fuses, you will get tired of changing them after a while.  That’s why I added the breakers.  I kept the fuses for redundancy.  Don’t want to blow the 20 amp fuses in the TIU.

BOB,

Thanks for the info.

Old Chuck