Fixed voltage between post war transformers

Common ground wiring with transformers in phase will allow exactly that and more!

With the common ground U to the outside rail, you can use the 6V or 20V fixed voltages of the KW. (The 14v fixed setting is not referenced for common ground use).

Unfortunately, neither of those fixed voltages is ideal for switches (12-16 volts is ideal for most switches). However, you can add a third transformer to your common ground setup and and use an applicable fixed or variable voltage for the switches. With the number of switches you have, this would seem essential and the cost of an additional LW, KW, VW, or ZW pales in comparison.

If you are using the capacitive discharge circuitry to shut off power to the switch machines after activation or when there are trains parked on the trigger rails, then the KW 20 volt fixed voltage would be ideal. The capacitors would charge quickly and to a nice voltage for snapping those switches over fast & reliably. There would be no discernibly extra load on the KW. 

I have the ZStuff 2500 switch machines on all my Ross Switches.  I was hoping to use the 14V fixed voltage plugs on my KW, but neither the C or D is a ground.  I am guessing this would be a problem as the switch machine instructions state the black wire should be connected to a ground.

Rob, I have no idea what the capacitive discharge circuitry is.  I would have no problem using the 20V, if I could.

Rob, please correct me if I'm wrong here, but regarding the KW, isn't the following true?

If U is used as the common terminal, then D is fixed at 20v and C is fixed at 6v, with variable voltage on A and B of 6-20v.

However, if C is used at the common terminal, then you get D fixed at 14v and U fixed at 6v, with variable voltage on A and B of 0-14v.

14v would be ideal for most accessories and switches.  The only downside is you get only 14 max out of the variable A and B.  I suppose it depends on what you are running on the the KW tracks and how fast you like to run them

JD