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On my previous DCS controlled layout, I used DPST toggle switches and isolated the center rail (hot) and one outside rail (ground) to maintain star wiring pattern with equal lengths for hot & ground wiring to each DCS block.  After reviewing this forum’s posts and Barry Broskowitz’s books, I wonder if I need to isolate the outside rail (ground) for each DCS block or if I need to maintain twisted-pair wiring to DCS blocks.

I would like to clarify the experience of others on this forum before I wire my new layout.  I plan to use SPST toggle switches to control power to the center rail (hot) of each DCS block, so all these DCS blocks will have insulated gaps at each end of the center rail. 

My questions are how to gap and wire the outside rail (ground) for each DCS block:

  1. Do I need to provide a matching isolated outside rail segment wired to ground for each DCS block?  In other words, do I need gaps in the outside rail (ground) for each DCS block?
  2. If I do not need gaps in the outside rail for DCS blocks, should I still add a wire to the outside rail to match the wire to the center rail for each block?  Should the outside rail (ground) have multiple wires?
  3. If I need to match wiring for gapped center rails and un-gapped outside rails for each DCS block, should I use twisted-pair wire or will any stranded wire of adequate gauge work well?  How important is it to keep center rail (hot) & outside rail (ground) wires to each DCS block the same length?
  4. If I do NOT need to match wiring for gapped center rails and un-gapped outside rails for each DCS block, how often should I install outer rail wires to ground?
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Using Fastrack, I used 18 awg drops to 14 awg feeder wires from two terminal blocks, one for each fixed TIU channel. The feeders are OGR twisted pair wire connected to center rail and out side rails. I only have isolated rails for signals. Center rails are blocked, outside rails are not. I have about 12 blocks for each channel, with only sidings on toggles. I have 10s everywhere, only an occasional 9. The layout is a 20' X 16 U-shape with about one scale mile of track for each channel. This is what works for me. Barry's book was on the table all during construction.

Last edited by John H

  You don’t need to isolate or block your outside rails. When you run trains. The wheels themselves will bridge them together. If you are using a form of paired wiring. Consider using relays. You then can keep your wire runs of heavy gauge wire carrying volts and track signal shorter. They can be mounted near the center of the layout.  Just make up a bank of them similar to a terminal strip. The automotive Bosch style can be easily mounted. Run your paired wires to the track. You will need a small 12v power supply. Use your toggles to turn the relays on and off with much smaller wires than needed to run your trains.

My layout was built before DCS.  It is 3 levels, 35x16, and any train can go anywehre on the layout at any time.  For conventional, many blocks means better control It has 70+/- blocks, each controlled through a SPST toggle switch on the control panel.  The panel is divided into 6 sections, each covering an area of the layout. From the panel a single 14-gauge wire goes to the center rail of the block, preferably near the center, 14 gauge all the way.  From the transformers' U posts, there is a loop of 12-gauge wire going completely around the layout.  All outside rails and accessory grounds are tied into it.

My son gave me a DCS system the week it came out.  No way was I going to rewire that monster.  I inserted original issue Rev G TIUs between the transformers and the control panel, and have been happily running DCS ever since (about 18 years).  I don't have star wiring, I don't have twisted pair.  I did place 18-volt bulbs across the rails at a few sidings; that's another, rather long, story.

Having the toggle switches is still great with DCS.  I can cut off a section where there is a derailment until I can get to correct it.  I can test equipment without activating other equipment.  I can kill trains so they don't start in stealth mode.

The late Marty Fitzhenry, who worked with MTH in developing MTH, also rejected the start wiring idea.  He also had common ground.  Forget the twisted pair and equal length c--p.

 My own layout. Is wired much the same as RJR just described. A pre existing layout built before DCS. Star wiring maybe the preferred method for good results. That doesn’t mean common buss wiring won’t work. I believe in 12 gauge buss wiring with 14 gauge feeders. Every 3 ft. section of my Gargraves flex is wired with drops. I think neatly done, solid connecting wiring is the key to good results.

 

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