Crosstalk between conventional track power wires and DCS/Legacy?

You should be fine.  Cross talk is a concern mostly with high and low voltage wires are mixed in the same bundle.  I would separate these. Low voltage cross talk happens frequently with wires with thin insulation in automobiles passing through small body panel holes. For train layout applications you should be fine 

Generally, if you have a Legacy base powered up anywhere on the layout, you’ll pick up the signal with TMCC and Legacy engines that you want to run conventional at the same time. I don’t know about DCS, but I’ve had that with Legacy engines on the bench where none of the wiring was connected or near the Legacy layout.

I think this is a non-problem.  You'd actually have to work at it pretty hard to make a separate conventional loop affect either DCS or Legacy. 

I would just make every loop capable of running conventional/DCS/TMCC, then you can run whatever you want anywhere on your layout. If you do that with the variable channels of the TIU or a Powermaster you have the advantage of being able to run conventional locomotives with a remote as well.

There is no electrical or electronic reason for separating conventional and DCS areas on a layout.

I thought the question was to possibly run both at the same time. Separate loops on the same layout. Is that not true? Obviously running one or the other at separate times is no problem.

To clarify, CJACK is correct.  I want to mix it up.  It's 10x14 but has 3 loops (one elevated), a yard (and a couple back and forths for trolley but don't count those in this discussion).  Though a bit complicated electrically I hope to design it so that I can run conventional or DCS/Legacy on any combination of the loops at an time.  

I certainly may want to run any PS2/3 or TMCC engine (don't have any Legacy as yet) on a conventional power district even if I won't get all the fancy features.  So just wondering if any nearby DCS track or even a cable under the table would make that command engine on a conventional track go goofy.  Only way would be crosstalk (EM radiation) between tracks or wires but I'm assuming that the signal strength would be terrible.

So from what I've seen from the responses is "not likely".  Will find out soon enough as I route the wiring.

Kirk R

"...even if I won't get all the fancy features"

Why not?

"Why not" works both ways really.  Maybe there is one remote & two people.  I know I prefer transformer handles, no ammount of wing-dings will change that. I haven't even finished my home spun Bluetooth sounds and I'm tired of it. It was fun for half a day, nothing earth shattering. It's playing Mr. Young's "Time Fades Away" right now. 

  You can shield the crossings with aluminum or copper, between them. Putting the shield to an earth ground usually helps more, but it would need to be a seperate earth ground from the one tmcc/leg. uses to avoid that signal. 

Bundlesare more likely to allow a jump, but it isn't an exclusive.  I've had other non-train data jump 3-4ft into other lines. At a restaurant, the order printouts showed up on neighbors machines, etc. ... 60ft away & thru a cinderblock wall.  It wasn't even the same system or brand of printer, lol.  They had hundreds of tickets and were out of paper before Monday morning.  We both shielded the lines better, and all was well. (I suspect they didn't use shielded wire at all at first)

Adriatic, note what he said, that if he ran a DCS loco on a "conventional power district" he wouldn't get all the features.  There is no DCS-dictated reason to have different types of dedicated power districts.  On my layout, I can run conventional or DCS anywhere, anytime, without throwing any switches, toggles, levers, etc.

 Command control blinders off.... He ..wants ..a ..conventional ..line.

He wants both that and command at once, not either or.  But at the same exact moment in time; both. Command on conventional and command at the exact same moment.

  How do you keep the command unit going when you drop the voltage to make a stop on that convetionally run unit? Of course you need to seperate things.

"Want's" is reason enough. "Doesn't care about features". ....Ok lets go...and we did...

There are going to be blocks/disticts/loops of different power, just like any blocked conv layout. 

Communication breakdown...

I'm not seeing how your statement relates other than to run one way or the other ....and.I can't really tell if you are asking about lost functions in conventional once I reread, Sorry if so. I thought for sure youd know that you will loose some functions sometimes. There isn't always a whistle/bell/combo type command for everything while in conventional,..fathom not using command to run a command engine or missed something.

John even misread the concern as that might effect the system line, vs the concern about the conventional line holding a command unit and shifting into command when it isn't wanted.

     I read he wants a conventional District, as in a totally- 100% isolated, variable transformer .handle voltage, non remote control operated, "loop/line/block".

 He does not want to shift into command mode by accidental jumps of data from basically another layout though only in away, intertwined, but isolated.

 I think the fear was loosing control while in conventional, because of a tmcc/dcs signal. 

I think, that he is thinking, there may be a  fear similar to that of a command unit shifting into manual mode and racing off.

   Unless he crosses a conventional onto the 18v command line he would be fine. I still addressed my own experience with data bleed and my solution. Might work if needed. 

If it shifts to command, drop power, and raise it slower.

He might choose sheilded wire too. It might be overkill, but there.

 Yes, I repeated myself in slightly different ways in hopes of clarification... if nothing else so someone might clue me as to what I am missing. That later statement was not obvious enough for me. Not wrong; I just don't see the tie.