When running a Buss wire does the wire go around the layout to be connected back at the  transformer or terminal block post in a loop OR could the wire just "dead end" somewhere?

Original Post

It would dead end. If I understand your question correctly, the wires would not start and finish on the transformer post. I would not suggest Buss wiring if you plan to use MTH DCS. Otherwise, have at-it.

Tom Tee

I will be using a Z4000 and DCS. Not at the wiring stage yet. I'm still trying to figure out how I'm going to tackle that. 

Gilly, thank you, you understood my question correctly. Since you brought it up, why not use Buss wiring for DCS? I've read a lot of posts saying not to but if someone has explained why I've must have missed it. Any info would be appreciated since I'm still deciding how I'm going wire the layout. 

@DJM posted:

When running a Buss wire does the wire go around the layout to be connected back at the  transformer or terminal block post in a loop OR could the wire just "dead end" somewhere?

I believe that full loop buss wiring works great with anything and everything, EXCEPT.............. MTH's DCS, where dead-end buss wiring (a.k.a. "Star" wiring) is recommended.

This based on a lot of reading I have done.  Admittedly, I don't have any experience with Lionel's or MTH's digital systems.  I do have plenty of first hand experience with conventional and DCC systems, where absolutely NO problems are experienced with full-loop buss wiring, that I am aware of.

@DJM posted:

Gilly, thank you, you understood my question correctly. Since you brought it up, why not use Buss wiring for DCS? I've read a lot of posts saying not to but if someone has explained why I've must have missed it. Any info would be appreciated since I'm still deciding how I'm going wire the layout. 

Do a forum search for DCS star wiring.

This involves  seperate pairs of feeders going out from the transformer via a terminal strip to individual blocks of the layout which are divided by gaps in the center rail.

Blocks are either certain lengths or a certain number of track joints.

This wiring preference for DCS has to do with the 2 way communication through the center rail/ hot wire of the layout.

Without the layout divided into blocks with separate feeders the signal can repeat and causes issues with the operation.

If your just beginning to wire for a DCS layout. I'd follow the recommendations for proper star wiring and save yourself aggrivation from signal issues down the road.

It's alot easier to wire a layout correctly the first time.

Last edited by RickO

The recommended method for wiring DCS is a Star not a buss. As I understand it the dead end we were discussing earlier results in a reflection that tends to kill the signal. The bigger the layout, the more likely you are to have problems. 

Our club has two small modular layouts; 6x11 and 12x15. Both are bus wired and have zero problems with DCS signals. Our 20x40 layout without the yard area, DCS is "OK". Add the yard with eight 20' stub sidings and the DCS signal is junk.

My home layout is 14x39. It is star wired with an older TIU. Signal strength was terrible until incandescent lights were added and the outer rails were tied together at each power drop. 

Regardless of how you do it, plan for a power drop every 6 track joints. Your loses are in the joints, not the rails. For making your connections, do a search for "lever wire connectors wago" on eBay. They are the best I have used.

Last edited by Gilly@N&W

Couple of thoughts:

For best DCS performance twist each pair of wires. 

On my last DCS job there were 20 to 45 foot runs, I clamped one end of the two wires at the far end of the room, strung it out it's full length, inserted the opposite end into a drill chuck and twisted away.

On the long runs the twisted wires want to get a tad crazy jumbled.  One thing you can do is to  wrap some electrical tape around the pair every 8 to 10 feet.  That will help to maintain a resemblance of order. 

I find it more orderly to try to keep each length of wire being feed into the benchwork as straight as possible laying on the floor as I  threaded each run through the pre drilled wire management holes in the cross members.  Maybe have someone feeding the wire to you as you are under the platform.  Otherwise it can be hair ball time.

When ever possible run a much of the wire  as you can standing up over the frame work before the decking is installed.

Mike CT  who is a real electrician uses a very professional wire management wire gutter with snap on covers.  Hopefully he will chime in.

When pulling each pair off a reel you may find it easier to set up the reel on an horizontal axle and pull the wire off much like a fishing line coming off the fishing reel.  If you lay the reel flat on the floor and pull the wire off sideways it can get curly jumbled with much of a run.

I use different color wire combinations and for the intermittent wrapping  of the pairs I use different color electrical tape so when you run or trace pairs you know whats what.  

HD or any electrical supply house sell handy frames for any size wire reels.

IMG_6981

You can slip on hot water pipe wrap to ease carrying the racks.   I eventually mounted them on furniture dollies to drag  round the layout.

I was told to attach the pair at the start or finish of each block for a better signal as opposed to attaching the pair in the middle of a block.

There are also alpha and numeric I.D. tapes we use for circuit identity.

 

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Last edited by Tom Tee

Modular guys use a loop bus.   My club terminates both ends of the loop at the TIU.  The bus has discrete ground lines for each loop (only tied together at the TIU for TMCC signal injection).  DCS works on large layout (200 ft. loop length) main lines.

I use a BUSS on my 15x33 DCS layout.  I use suitcase connectors at the BUSS and solder the leads to the rails.  The one thing I didn't do that I should have was to block the track sections for each drop.  I still could, but I'm lazy.  The furthest section of the layout from the TIU sometimes gets a double horn/whistle.

OGR's own Alan Arnold showed me how.

Have Fun!

Ron

Do yourself a huge favor and buy Barry's book from the MTH site. It explains the DCS wiring and also block wiring. It will tell you all the nitty gritty and you will not be sorry. It also will help with all aspects of DCS including WiFi App. His DCS Companion is out of print but the DCS WiFi Companion MTH still sells. It is the GO TO BIBLE!! Explains all the functions of DCS and WHY! You can also get the download version which allows you to do a search of the book.

I'm with the STAR wiring crowd and also recommend Barry's book highly.  You will use more wire with STAR wiring but you will get results.  I used STAR wiring from the get go and have no DCS issues.  Buss wiring is easier, faster, less expensive and can be more prone to DCS signal loss and voltage drop issues..  I find that STAR wiring makes troubleshooting and modifications easier too.

I believe that full loop buss wiring works great with anything and everything, EXCEPT.............. MTH's DCS, where dead-end buss wiring (a.k.a. "Star" wiring) is recommended.

This based on a lot of reading I have done.  Admittedly, I don't have any experience with Lionel's or MTH's digital systems.  I do have plenty of first hand experience with conventional and DCC systems, where absolutely NO problems are experienced with full-loop buss wiring, that I am aware of.

You refer to Star Wiring as "dead End" buss wiring. So, wouldn't running a set or two of "dead end" buss wires, capped at their ends, to the ends of the layout and making drops from each block along the way be the same as having long runs of wire drops from each block BACK to a central terminal port?  I would think that having more long runs of wire used in the "Star Wiring" diagrams I've seen would leave more chance for there to be an issue with signal.  

@Ron045 posted:

I use a BUSS on my 15x33 DCS layout.  I use suitcase connectors at the BUSS and solder the leads to the rails.  The one thing I didn't do that I should have was to block the track sections for each drop.  I still could, but I'm lazy.  The furthest section of the layout from the TIU sometimes gets a double horn/whistle.

OGR's own Alan Arnold showed me how.

Have Fun!

Ron

Is the BUSS in a loop that connects back to a terminal post or do the wires "dead end"?

@DJM posted:

You refer to Star Wiring as "dead End" buss wiring. So, wouldn't running a set or two of "dead end" buss wires, capped at their ends, to the ends of the layout and making drops from each block along the way be the same as having long runs of wire drops from each block BACK to a central terminal port?  I would think that having more long runs of wire used in the "Star Wiring" diagrams I've seen would leave more chance for there to be an issue with signal.  

Nope. If I understand you correctly, that would cause all sorts of problems.

Look at it this way: every block or every track drop has to have its own individual lead to the power source. If you have more than one drop on the same wire lead, the loco will get the original signal and another identical signal from the second drop a few microseconds later. The MTH system operates at extremely high frequency so there are problems like standing waves and reflected waves. It's basic high frequency lead dress and such.

Do you remember "ghosts" on the old TV system? That was where one signal came straight to the TV and a second signal bounced off a building and arrived at the TV a few microseconds later. Feed that kind of a dual/repetitive signal into a microprocessor and it goes nuts.

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