TMCC Connection

In most layouts, all the outside rails are common.  Connecting all the Z-4000 commons and connecting it there is a good choice, that will work fine.

After searching the forum this topic seems to be the most closely related to my question.  I have mostly Protosound 2 or 3 engines, but a couple TMCC, Legacy, and conventional as well.  I have a simple setup with two loops around my ceiling which I supplement with floor layouts for the Christmas season.  My power is a ZW-L running through a TIU.  Each ZW-L output feeds a different channel of the TIU, which feeds a different loop.

I have a command base connected to the TIU with the "one wire" going to the TIU output for the loop on which I run the Lionel trains.  I've been able to run all of my engines through DCS wifi, and can still control the conventional engines from the transformer if desired, and I know they say if it ain't broke, don't fix it, but I was interested in getting a Legacy command base to access the Legacy features.

My questions relate to figuring out the best way to connect the new Legacy command base to my layout.  Given that the Legacy remote is specific to the legacy features, I don't foresee wanting to control the Legacy trains from the DCS Remote anymore.  The only benefit I could see to connecting the new command base to the TIU would be I already have DCS wifi, so I wouldn't need to buy the LCS wifi or serial modules.

My TIU and Command base are stored in a shallow drawer that I store under my couch, but given that the Legacy command base is also the charger I don't really want to store it under there, which brings me to the questions:

1. The ZW-L has a post on the back for the Command Base wire.  This is the shortest and most convenient connection to make, but it would mean that the command signal is going through the TIU.  Is this okay for the TIU?  Would it work?

2. The distance from the TIU to the track is about 8 feet.  Would adding an extra 6 feet to the command "One Wire" cause signal issues?

3. If I want to run Legacy/TMCC on multiple track loops, do I need to put a jumper between the grounds on the TIU, or are they connected internally?

Thank you for any assistance you can offer!

@William V. Derr posted:

1. The ZW-L has a post on the back for the Command Base wire.  This is the shortest and most convenient connection to make, but it would mean that the command signal is going through the TIU.  Is this okay for the TIU?  Would it work?

It's not recommended.

2. The distance from the TIU to the track is about 8 feet.  Would adding an extra 6 feet to the command "One Wire" cause signal issues?

No.

3. If I want to run Legacy/TMCC on multiple track loops, do I need to put a jumper between the grounds on the TIU, or are they connected internally?

Depends on the TIU.  Earlier models the commons are tied together.  Later models are not.  Not exactly sure what REV this changed.  If the loops connect, chances are the commons are already joined by virtue of the 3rd rails.

Thank you for any assistance you can offer!

Thanks for the quick reply!  

I'm pretty sure my track loops are isolated (and probably the TIU outputs as well).  When I built the layout I was having issues with the switches getting stuck in the curved position.  I put isolation gaps on all the rails between the loops and that problem was solved.  (I'm guessing that at some point in wiring the track I made a connection to the opposite outside rail and that was somehow activating the non-derailing feature of the switch).  It hasn't caused me any issues since I put in the isolation gaps, so I've left it alone.

For TMCC to work properly, ALL the layout has to have at least one outside rail common and tied to the command base.