Separate ground bus for TMCC/Legacy system

Why?  You should be able to have a common ground throughout your layout if you like.

Rescued Trains posted:

Am I understanding this correctly? If I use my Z4000 to power 2 independent loops of track (TMCC and conventional) I shouldn't use the 2 fixed voltage outputs for any accessories. In fact I should have a separate transformer for accessories with a  ground bus separate from the Z4000.

Steve

What makes you think that?  What did you see that makes you think this is the way to go?  One Z4000 for two loops and accessories should run great with Legacy. 

When you say one loop is conventional go you mean you'll run conventional only engines?  If so, no issue,  if for some reason you looking to run TMCC/Legacy engines on that loop in conventional mode then you'll probably have problems as TMCC/Legacy will probably bleed from one loop to another even if you run separate transformers.

Chris, first I am a total novice when it comes to TMCC and DCS systems. That being said I was impressed by Mike wolf's presentation at York (on YouTube), so much so I bought the DCS Companion book by Barry Broskowitz. After going through the book, which is excellent, I felt that there was a lot more to DCS than I wanted to get involved with (wiring, modules). So I turned my attention to TMCC and bought "Modern O gauge Remote Control" by Bob Phillips and Joseph Stachler. This is a TM book that is endorsed by many prominent people in the toy train industry. So my question comes from the TM book, on page 25 it says "To prevent the possibility of accessories causing signal interference connect them to a separate power source, including ground. This means that a second common ground line completely isolated from the track's common ground is installed under the layout for accessories."

Also noted in the DCS Companion book on p78, "It's strongly recommended that a separate transformer be used to power accessories."

Just trying to learn so I can move forward with my layout without creating a problem I'll have to fix later on.

Thanks, Steve

It's never a bad idea to have separate power for accessories, but it's certainly not required.  I have a number of accessories that are TMCC command controlled, if I used a totally separate ground for them, they'd stop working!  I haven't seen the book you reference, so I have no idea of the validity of all their suggestions.

I 2nd Gunrunner.  The recommendations in the book are new to me.  In fact many large transformers (including the MTH Z4000) have separate power taps for 10 and 14 volt accessories.  1 transformer, several taps.  I think you'd  be fine with this kind of set up.  In any case accessories (for the most part) shouldn't be run from the track power tap.  Different voltage requirements.  A separate transformer wouldn't hurt but is probably an unnecessary expense and complication if you not building an elaborate lahiut.

And you're doing the right thing.  Asking questions is the best way to learn.

You know what they say....the only stupid question is the one unasked.

Good luck with your layout!

While most cases the track transformer common with the Legacy powering accessories is fine.  There are many older accessories that will definitely have a negative effect on the signal such as metal bridges (the Heckgate comes to mind), metal signal bridges, and metal trackside items.  I've experienced it from all of them.  Sometimes a ground signal radiator wire will help overcome this.  When I don't need an accessory to operate in conjunction with the track such as just to light up or discrete from the layout I typically use an seperate transformer without the Legacy signal.  This isn't always possible.

Bob Phillip's book is very good but as I said sometimes you can't get away with not using the track power.  

A Z4K's commons I believe are tied together so when you add the "one wire" the Legacy signal is on all other commons.

For our club modular layout, we stipulate that accessories are powered separately from the main lines.  This is based on years of experience starting with conventional operations in the pre-TMCC era where a faulty accessory (shorts, etc.) would stop main line operation and caused frustrating troubleshooting efforts while visitors wanted to watch the trains running.  DCS signal demons made our standards evolve to requiring that all main lines have their own discrete grounds.  The grounds are joined (i.e. common) at one place - the TIU outputs - and that is were we connect the TMCC signal input wire.  The lesson here is the more you strive for separating the operating components of your layout, the easier troubleshooting becomes.

A home layout, where one individual (you) are the only cook stirring the wiring implementation, can be less formal.   You can track down which of many of the accessories that failed a bus at your leisure.

Practically speaking, I try to use a lot of accessories and lights on my modules.  Since multiple voltages are required, I have a collection of small post-war transformers that are put into service for specific accessories and trim the voltage for best illumination and operation.

For our club layout we also have a separate accessory feed with it's own transformer, but that's because we have no idea what might be camped out on that line.  We also feed any sidings with separate power as well.

gunrunnerjohn posted:

For our club layout we also have a separate accessory feed with it's own transformer, but that's because we have no idea what might be camped out on that line.  We also feed any sidings with separate power as well.

John, Separate power and common for accessories?

I buy the power being separate, but there's no screaming reason for separate grounds.  If you have any TMCC accessories, separate grounds will also be problematic.

Thanks to all for the input. Based on what I have gleaned from the comments and suggestions I will use a common ground bus for the entire layout (track and accessories). Also will not hesitate to use the 2 fixed voltage outputs on the Z4000 for accessories. If in the future more power is required I would add additional transformers (phased of course) still using the common ground bus. Again thank you all.

Steve