Running Dual Command Systems

Well, you certainly don't want to be feeding back voltage to the ZW on it's outputs, that can't be a good idea!  The TIU actually will run in passive mode with only a track connection to the Fixed #1 output, so it shouldn't hurt that one.

Dumb question.  Why not simply wire the ZW outputs through the two DCS fixed channels and feed each of the two tracks, from the two channels?  This will allow you to run any combination of conventional, TMCC, or DCS.

Dumb question answered: This is one of many individual loops on my layout (I have a Subway loop, El loop and two ceiling loops...This is for the table loop). At present, all "accessories" are controlled through the two inner handles of the ZW, thus allowing me to power them with 14 volts. I only have one ZW handle  and one TIU port available/left. (Where possible, I've run power to the TIU and then to the loop tracks and simply attached the TMCC  signal to the outer rail....thus allowing me either TMCC or DCS) On this particular loop, I want the convenience of running conventional. (Easier access to take engines on and off) I am trying to use what I have. I really don't want to buy more stuff. I don't want to be known as a hoarder...just a collector!

So, I will have to wire a DPDT switch in line with each power loop, so their will be no feedback voltage to either the TIU or ZW transformer.

Thanks

PS. Unless you are going to send me another ZW and TIU for Christmas...I've been a good boy!

I mistyped....DPST switch in each power line

I think you were in the right track with the DPDT.  one switch and no chance that you turn on both supply sources.  

Also I'm not really familiar with how the TIU operates, but couldn't you use the ZWL to power the track at all times and use the passive connection to the tiu to supply the DCS signal?  Is that not how it works?  

Why not pick up 1033 transformer to power the "accessories"? The 1033 are cheap and easy to rebuild if need be.