Feeder wire length Lionel Strang vs Allan Gartner

greenspun.com : LUSENET : Wiring for DCC : One Thread

In Lionel Strang's book "DCC Made Easy" pg.12&13 he quoted as saying, "track feeders should never be more than 3 feet long; for this distance you can use thinner wire (20-22AWG) because the resistance created over 3 feet is minimal."

In Allan Gartners web site, "Track Wiring Part II", he is quoted as saying " Try to keep your track feeders to about 6" in length or less- especially if you are using the smaller sizes of wires than I suggest for your scale (20-24AWG).

I see quite a different philosophy when it comes to this. In my personal situation, I have a Prodigy advance system. The layout is basically a takeoff of George Sellios's "Franklin and South Manchester" ref;Model Railroader March 2003. I plan on using 14AWG Bus wire with 20AWG feeder.

The problem I have is the each leg or area of the layout is no more than 4' wide. If I folow Lionel's Strang's advice, I only have to run one set of bus wires down each leg of the layout to come within his 3ft. rule. If I follow Allen Gartner's advice, I have to run bus wire under every line of track. Who Prevails! This is thing about DCC in my mind, there are no norms, everyone has their own way of doing things and their reasons for doing it.

I invite you to this debate and please, someone explain it to me in plain english

-- Lorne Martin (tinbasher41@shaw.ca), January 31, 2005


It's not about Lionel's rules Vs Allan's guidelines. It's about what you expect from your layout, and your tolerance for for things that don't work quite as perfect as they could be. You will always find someone with anecdotal evidence of an exception to every rule or guideline. Your challenge is to sort through the hype and determine practical needs of your layout. Then you can formulate your own set of DCC installation guidelines.

In your case, it may be unlikely that you will be using long consists that tend to be found in large club sized layouts. So you can get by with skimpy wiring. If you are using older style current hog locos then you may need low resistance feeder wiring (fat bus and short length rail feeder drops of smaller ga) to prevent voltage/speed droop. This can be important for mainlines, especially at grades or a helix. However, it may not be all that important in a classification yard. So, go ahead...Wire it up with a single DCC bus run down the middle. Just use plenty of feeder drops....Enough so that every section of track that has unsoldered rail joiners has one, and that the end of the rail section is not more than 3 ft away from the feeder drop. (again just an idealistic guideline number) Poor electrical connections (high resistance) is the #1 problem with DCC.

But it is your railroad. If you take the more conservative route to all of the posted suggestions and guidelines, it is almost certain to work. For every short-cut you take, there is at least one problem waiting to happen. If you are careful, the problem won't show up on your layout. But it does take the fun out of running trains if you spend time nursing a loco through poorly electrified track.


-- Don Vollrath (dvollrath@magnetek.com), January 31, 2005.

Hi Lorne

Simply put, the thicker the wire (gauge) the less resistnce per foot causing a voltage drop and this voltage drop is determined by the amount of current flowing. This is Ohms Law, R = E volts/I amps. With voltage drops more than say 10% it may show as a loss of loco performance and can cause heat and may possibly effect the booster/circuit breaker shuting down with a short circuit.

Now for the wiring that is carrying a lot of current say 5 amps, the power/track bus you use 10 - 16 gauge depending on length, this is quite a range but for feeders that are very short 1 to 2 feet much less current, less than 1 amp flowing in this piece of wire you can use much smaller 18 - 22 gauge, due the each piece of track is wired, but if longer use 14 - 18 gauge. It has all got to do with wire length, resistance per foot (gauge) and current flowing.

Use the thicker wire if you don't understand the theory here. The down side of thicker wire is cost and harder to use, but safer in the long run and less chance of a loss of loco performance. This also ensures correct operation of all components.

Both Allan and Lionel are right. You have to look at your own requirement (layout) and work it out or use the thicker recommendation. Remember Allan, Lionel and me have given you some guidelines We dont know your individual requirement.

-- Marcus Ammann (mammann@optusnet.com.au), February 05, 2005.

Moderation questions? read the FAQ