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I am about to convert my conventional, block-wired layout to MTH's DCS system.  I currently use a ground bus for the 4 loops of track (2 of which are connected by track switches but separated by insulated blocks) as well as AC accessories.  The on-line DCS manual mentions something about avoiding bus wiring - but gives no explanation why, and I can't really see a problem with a common ground for all the loops and accessories.  Does anyone know if I really need to separate all my grounds for the track loops?



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Dale, my Run Room bus wired tracks have been powered with the DCS system since DCS was introduced.  My common bus is fed with larger size wire than my center rail block wires. 

Instead of rewiring your layout go ahead and set up your DCS TIUs with 1 TIU output powering each of your blocks.

Here are tips for improving the DCS signal if needed after setup:

  • Before checking track signal on a model train layout, be sure the track and wiring installation is sound.
  • Run trains in conventional mode for a while to be sure there are no electrical dead spots or faults.
  • Blocks must be insulated at the center rails.
  • Rail must be clean for conducting signal to and from engines and operating cars.
  • Pickup rollers must be clean inside and out. (Use electronic spray cleaner from auto parts store for cleaning.)
  • Power wires must be large enough to carry anticipated current.
  • Tap wires to track from power bus can be 14 or 16 gauge solid and should be soldered to track. The common wire (to outside tracks in 3 rail) must be larger than the feeders (variable voltage wires) when there are two or more feeders in a run.
  • All wire should be loosely supported and untwisted.
  • All wire connections must be tight enough so the wire cannot be pulled out of the connection.
  • Limit track length in a block to 90 feet or less. When feeder wires to track are tightly bundled (as in conduit or wireway) the track lengths will probably have to be shorter.
  • For switched track use switches rated at a minimum of 5 amps.

Good points on wiring from Susan, good sound wiring is important.

I agree with John H above about the center rail blocks being the most important. Those make a difference, at least they did for me. The outside rails being all connected anyway do form common bus as he also points out. My layout is wired that way and works just fine.

The center rail blocks eliminated all my DCS problems, except operator error.   I'm working directly with the operator on that one, but I don't think his memory is quite as good as it used to be...  

Good thread and thanks to all for the information.  I am doing the same thing Dale did and am curious about the ground connections on the TIU relative to my common ground bus. I plan to start with a 180 W powerhouse connected to the first three channels of the TIU with Jumpers. 

1) Do I need to jumper the output terminal grounds together too or is this done internally based on the inputs being connected? Seems I read somewhere that TIU Rev L does not have the ground terminals internally connected.

2) Will a single connection from the ground bus to the TIU ground connection at the input from the powerhouse be sufficient or do I need to tie both input and output to the ground bus? (everything is phased correctly)

Bingo, you just described the wiring plan I had in mind.  The mystery for me was what went on inside the TIU as far as the grounds. Now I can ignore that by connecting to the output. My old layout only used one TIU output and was limited to one DCS loop.  This new layout will have DCS on all tracks, assuming DCS survives the next several years.  Oh well, there is always LC 2.o +.

PS- time to buy your season tickets!

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