Lionel Strang vs Allen Gartner Feeder wire length

Discussion in 'DCC & Electronics' started by tinbasher, Jan 31, 2005.

  1. tinbasher

    tinbasher New Member

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

    In Allan Gartners web site he is quoted as saying "Try to keep your feeders 6" in length or less-especially if you are using the smaller wires I suggested (20-24AWG) for your scale. when using the larger sizes suggested for your scale, try to keep the feeders to about 12" in length or less."

    Now I have a problem, if I use Lionel Strang's advice, I only have to run one set of 14AWG bus wires for each leg of my layout. If I use Allen Gartners advice I have to run bus wires under the the entire layout. My layout is no wider than 4ft at any point.

    Now the debate begins! If anyone can convince me one way or the the other based on fact in PLAIN ENGLISH I will go with it. This is a crucial step in wiring my layout and I really need yor guys help on this.

    Thanks :)
  2. siderod

    siderod Member

    If Allan is correct, then i am soooooo screwed! I've got feeders on my layout that are nearly 6 FEET, let alone 6-inches. That said, i have NO problems with voltage drop, poor running or anything like that. Most of my feeders are about 3-feet in length.

    IMHO, i suggest you go with Lionel. I can almost promise you won't have problems, and it'll make life alot easier for you.

    Hope i can help!
  3. Tileguy

    Tileguy Member

    I found stangs DCC book to be very poorly done.That said,I would follow Allen gartners advice for DCC to insure good signal performance.Its a liitle extra work now,but less worries later.

    A trick that you can use would be to use a heavy gauge bare copper length soldored and run from your bus and then run your 6" feeders to it in heavy trackage areas.
  4. CalFlash

    CalFlash Member

    I wired my friend's layout for DC and he's now going to DCC. I did not follow the current DCC recommendations and he apparantly has no problems. If (and I am) doing DCC starting out, I would (and am) following Allan Gartner's advice. I have a fair sized layout (13' x 32') with some wire runs to 40+ feet so am using #12 for the buses and usually #16 off that reduced to 18 or 20 the last 6-8". I install feeders every 6' but they are "Y-ed" for the last 6-8" and soldered to both rails so in effect, every piece of rail has a feeder.
  5. Fred_M

    Fred_M Guest

    This is a funny thing to debate about condsidering wire is dirt cheap. Just run your feeders as a bus, or point to point, with 14 awg and run the light feeders a few inches through the base to the track. Just spend an extra buck or two and build it 30X better than it need be and forget it. LOL Fred
  6. moria

    moria Member

    Greetings :)

    The answer is try it and see...

    assume you can go with 3' feeders and run a short bus wire out and then run a feeder.

    Drop a quarter on the track.. if the booster shuts down, then its working fine and you can go with 3' feeders:)

    If it was 6" then my layout would be in real trouble. I think I have even exceeded the 3' in a couple of cases, but everytime I add a new set of feeders, I always do the quarter test to check. If that works, then the layout will work:)

  7. theBear

    theBear Member

    Now, now run two 1" square copper bars down the centerline of your track. From said bus bars run single aught feeders to each foot of rail.

    Toss a quarter on the track and if the power supply shuts down decrease the size of both the buss bars and feeders. Continue in this fashion until the power supply doesn't shut down, now very quicky (before the fire starts) backup one step. RALFAFE (running around looking for a fire extinguisher ;) ).
  8. hminky

    hminky Member

    I ran my layout for several months without "correct wiring" and it ran fine. It was jury rigged with one set of feeders and alligator clip jumpers to the reversing module. I have since cleaned up my act and wired it with feeders. I have a webpage about my adventures:eek: :
    Sometimes I think this is a case of over thinking:curse: .

    Just a thought
  9. theBear

    theBear Member

    Seriously now, there are two things to consider when wiring:

    1: Safety.
    2: Safety and operational reliability.

    If you do the wiring for safety you should also be very very close if not spot on for operational reliability.

    The only thing not covered in operational reliability by the wire for safety requirement is possible induced signal noise or signal degradation. Thus the few twist per foot for DCC & Pulsed DC vs pure DC or low frequency AC.

    Short and too the point wiring is a blessing in the operational reliabilty areana as is the extra feeders it usually requires, think redunancy (a bad solder joint or two will be effectively bypassed as a problem). As Fred stated wire is cheap. Lives, buildings, and models are not.
  10. CalFlash

    CalFlash Member

    Another thought on wiring. I rushed a little and tried to run trains thru an auto-reverser that also is supposed to throw the turnout before I had in adequate feeders. I had all sorts of erratic results which went away once I got in all the feeders per reccomendations.
  11. MilwRd

    MilwRd New Member

    After doing a quick calculation, I have to agree with Lionel Strang. The DC resistance per foot for 20 AWG wire is about .0064 ohms. At 3 feet that makes the resistance about .019 ohms. Ohm's law (V=IR) tells us that at a current of 1 amp the voltage drop in a three foot run is .019volts. Granted, it will be a little higher at DCC frequencies, but they are not high enough to make a significant difference. Dropper runs of a few feet should make no difference.

    Maybe I'm right, maybe I'm wrong, but that's the way I see it!
  12. billk

    billk Active Member

    Somewhere above someone mentioned BARE (ohmigod) wires. Think about it, aren't the rails themselves the same as bare wires? (Only they're on top where things can fall or be set on them to cause shorts, where the wires are usually on the bottom!) :D
  13. theBear

    theBear Member

    Actually both are correct in that the method proposed will work.

    I am however in agreement with Fred.

    I normally abide by the electrical codes that say if the circuit has a y amp supply at x volts the wiring had best be able to handle both the voltage (most wire fits here) and the current if the supply is shorted (there are tables for this).

    Anything in excess of the code is for reliability. Keeping the feeders from the bus short keeps down the voltage drop and increases the number of feeders to a section (which increases the current handling capabilty of that section always think short) allowing your engine(s) to operate reliably.

    As Jerry noted in his post strange things happen when auto-reversers and auto throwing turnouts are in the loop, the auto-reverser works because it detects a short (see above about current handling, safety, etc..) and there are not enough feeders.

    As an aside if you do consisting the current draw is increased in those feeders. So depending on scale and operating decoder features a consist may draw several times the 1 amp nominal rating we toss around.

    There are usually several "correct" ways to reach a goal. The goal and the path to it do not have to be the same for everyone. Sometimes a new path opens up faster, cheaper, more reliable ways of doing something and sometimes not.

  14. theBear

    theBear Member

    You got it Bill , you have in fact got it.

    You are lucky it is BARE and not Bear wire [​IMG][​IMG] [​IMG][​IMG].
  15. Fred_M

    Fred_M Guest

    And if you run feeders in at several points then the whole layout becomes a power network because the track is also a conductor, so a percentage of the load will come from all the feeders, it all will not all come from the one wire the lokey is closest to. It would take a very big equation indeed to calculate the voltage drop in one piece of wire alone when all eight would be interacting to supply power. Say one wire carried more load at a given time than the others. It's resistance will generate heat and the resistance of wire increases with tempature. So it would warm up slightly and it's resistance would increase slightly which will then shift slightly more load to another wire (actually wires) in the network which will then get warmer as the other cools until an equalibrium is obtained. But since the lokey is hopefully moving the network will be in constant change. Sounds like something for somebody with way too much time on their hands to figure. Just run some heavy wire and forget it guys. Fred

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