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Buss Wiring Standards

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  • Member since
    December 2004
  • From: Bedford, MA, USA
  • 21,483 posts
Posted by MisterBeasley on Sunday, September 13, 2009 7:59 PM

A lot of these "best practices" are just that.  They are the right thing to do, particularly if you are building a very large club-sized layout.  For the average home layout, though, you really won't see a difference.  I did not loop my track bus, but I certainly did loop my track, and without any insulators.  I don't see any particular performance issues as a result.

By the way, my track bus is 18 AWG wire.  Heresy.  And it works just fine for my home-sized layout.

It takes an iron man to play with a toy iron horse. 

  • Member since
    July 2006
  • 3,312 posts
Posted by locoi1sa on Sunday, September 13, 2009 6:35 PM

 Actually not wrong at all. You can loop the track buss. But on the other hand it does have a cleaner wave form if it is a straight run or a tee section. Square wave AC signal is easily corrupted. You may notice a slight difference in throttle response and even your sound decoders may not hiccup any more. Since we do not always program on the main all the time having an uncorrupted signal will hardly be noticed. Also some systems like Lenz and NCE can reduce the number of packets being sent to decoders. Some guys getting into a feedback system having a looped track and buss may notice some corrupted data being received.

  When DCC started coming out the standard for track buss was to keep the wires separated by at least 8 inches. Then there was all kind of RF interference and the standard had changed to a recommendation to twist the buss wires. Some separate and some twist. I personally have had problems with a corrupted signal from a key fob on a friends home layout. At one show there were 9 operating layouts in a small gym. There was all sorts of problems that weekend. From power surges and losses to cross talk on radio throttles. Runaways and collisions were very frequent. I had a steam engine sit a blow the whistle until I removed it from the track. When I got it home it was fine.

  There is no right way and wrong way to wire your layout. A solid loop that has worked fine for a number of years may not notice any difference. But if you add on to your layout then I suspect you may have problems. One two or even three trains running will be fine. Build a club size layout and have 20 plus trains running then a clear strong signal is a must have.

      Pete

 I pray every day I break even, Cause I can really use the money!

 I started with nothing and still have most of it left!

  • Member since
    February 2002
  • From: Reading, PA
  • 30,002 posts
Posted by rrinker on Sunday, September 13, 2009 6:29 PM

 Thing is, if you runt he bus in a complete closed loop and attach the booster to it, there shouldn;t be any signal problems because the path around is exactly equal. I can see there posisbly being some timing issues if one 'side' of the circle ahs more joints (instead of a continuous run of the bus wire), or for a section you substituted a smaller size of wire because you only needed 4 more feet and were out of the heavier wire or something.

 If you were having issues, you'd see it manifested as control issues with locos located at the furthest point from the booster. Slow or no response to speed and direction changes, or function commands. Things liek that are a sign of a degraded signal. Also possible runaways if you don't turn off analog operation in CV29.

 Perhaps it makes a sifference if your 'loop' is 1000 feet of track/wire around a large room - but in a layout that large you'd need multipel boosters simply because of voltage drops over such a large distance. With 1000 feet in a loop, the furthest point from the booster will be 500 feet - and even #12 wire will drop a few volts over that distance.

 This is why physical size ahs little bearing on how many 'amps' (ie, how many boosters) you need. A small layout that allows 20 trains to run probably needs more than 5 amps. A giant layout that only runs 2 trains but has 1000 foot bus will need more than 1 booster just to prevent voltage drop.

                                      --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

  • Member since
    April 2004
  • From: Ontario Canada
  • 3,574 posts
Posted by Mark R. on Sunday, September 13, 2009 5:47 PM

Actually, this is the funny part ....

I've been running my layout on DCC for about ten years now. There wasn't an over-abundance of information available at the time, so I wired it to what just made sense. My main buss is one long continuous loop out and tied back in. My layout really is one (albeit very large) loop and I've been running it that way all these years with not much trouble at all.

Now I'm reading neither the buss OR the track should form a continuous electrical loop. The rails should have at least one place where double insulators prevent it from being an electrical loop .... like-wise with the buss should not be a loop, but rather stub runs of no longer than 30 feet with an electrical snubber between the two wires at the end of each run.

My comment about being "over-kill" was from the fact I've apparently been running my layout for almost ten years with wiring that's all wrong ! (?)  What are the potential consequences of my wiring should I have been seeing ? If it's been working this well wired wrong, how much better will it work if I were to modify it to the recomended proceedures of today ?

Mark.

¡ uʍop ǝpısdn sı ǝɹnʇɐuƃıs ʎɯ 'dlǝɥ

  • Member since
    March 2007
  • 2,751 posts
Posted by Allegheny2-6-6-6 on Sunday, September 13, 2009 5:32 PM

 Go to the LHS or onlne book store here and but DCC made easy, it's a must have if your getting into DCC trust me.

If after reading the book you still don't understand dcc then stick with Dc because this guy made it so simple even a knucklehead like me understood it perfectly. You will find that the things you now think are over kill are in fact very good practices to adhere to and in the long run will save you a pile of money and heart break. For example circuit breakers on your DCC layout and how and where to use boosters on your layout.

Just my 2 cents worth, I spent the rest on trains. If you choked a Smurf what color would he turn?
  • Member since
    February 2002
  • From: Reading, PA
  • 30,002 posts
Posted by rrinker on Sunday, September 13, 2009 2:31 PM

 If you layout is a loop there's nothign wrong with the bus also being a loop. What can;t loop back on itself is most DCC systems' control bus - where you plug the throttles in. Track power, it does not matter.

                              --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

  • Member since
    April 2004
  • From: Ontario Canada
  • 3,574 posts
Buss Wiring Standards
Posted by Mark R. on Sunday, September 13, 2009 2:01 PM

According to "proper" practices, the track buss should not be run as a continuous loop (from the power station, around the bench-work and re-attached at the power station at the opposite end). So instead of a continuous 60 foot buss loop, I'm supposed to have instead, two 30 foot stub-ended buss runs.

I understand the reasoning for this is to avoid collisions of the signals being carried on the line. Ok - fine .... but isn't the continuous loop of track the buss is ultimately connected to put it right back into the same scenario ? Should there also be a break in the track itself so the tracks don't form a continuous electrical loop as well ??

Seems to me these wiring practices for "proper" installation become defeated once they are connected to the track ! Am I missing something or are a lot of these wiring practises unnecessary over-kill ?

Mark. 

 

¡ uʍop ǝpısdn sı ǝɹnʇɐuƃıs ʎɯ 'dlǝɥ

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