ARRGgggg...confused about wire gauge?

Discussion in 'DCC & Electronics' started by vanda32547, Oct 31, 2004.

  1. vanda32547

    vanda32547 Member

    I have read a number of posts about wiring DCC layouts. I have many spools of AWG 22 and want to know if this will work or if I need a heavier gauge wire for my layout? :confused: Any help would be appreciated.

  2. theBear

    theBear Member


    Wire usage is determined by the current the load to be powered will require, the length of the run, and the voltage needed at the load.

    Higher guage numbers mean smaller current carrying capacity and higher voltage drop per foot.

    Normaly you can do a trade off, however you have to meet the required voltage and current requirements at the end of the run plus enough of a safety margin to prevent melted wires, insulation, and a FIRE.

    Here is a nice place for information:

    If the item you are going to power requires under 0.9 amps (n scale loco for example) then a AWG 22 feeder at the rated voltage would work. However you must take the length of the run into account to make certain that you are fine.

    Now what most folks would do to make certain that everything was going to work smoothly would be to run a large guage bus under the track line and run smaller guage feeders off of the bus. This serves several purposes, the only one I'm going to mention is that it is makes a good solid set of eletrical connections.

    Remember to perform the old standby short test (quarter across the rails, etc...) to make certain your power system breakers trip without causing any damage.

    It always a good idea to be conservative in the area of electrical wiring.

    DCC also requires a better set of connections because the command system is always talking to the decoders. As I understand it long DCC power runs should also be properly terminated because of this and a related decoder destruction possibility.
  3. Fred_M

    Fred_M Guest

    If you run multiplule 22 gauge feeders to different areas of your layout from the power unit they will all supply a % of the total power because we need to remember the track is a great conductor too. Most of the current will flow down the shortest path (or least resistant) until it starts to warm up, which will increase its resistance, which will then cause more of the power to flow down another path. It will become power a power grid network and will work fine as long as there are mulitiple 22 gauge wires from the power supply (or DCC) to the track in several points on both rails. Fred
  4. 60103

    60103 Pooh Bah

    The 22 gauge wire should work if you're feeding an area that will just have one loco in it -- maybe a yard of track. 22 gauge feeders on every length. But these have to be tied to a bus that will handle the full current for your layout (or power district). This is where your heavy wire comes in -- should handle 5 amps. If you need more than 5 amps (in HO) you must think about more power districts.
  5. Matthyro

    Matthyro Will always be re-membered

    I tried different gauges and have found that a heavy gauge wire sure pays dividends when it comes to smooth operating. My minimum is 18 gauge. When it comes to reliable operating don't skimp like I did initially. Had to take it all down and re-wire with the 18 gauge.
  6. vanda32547

    vanda32547 Member

    In the past for DC operations, the 22 gauge wire worked fine, and yes I did have multiple points of power through out my old layout however on my new layout I am going DCC (and can't wait to try it out). The problem I have is very little under layout access since the layout in built on top of kitchen type base cabinets. So I want to do it right the first time so I don't have to mess with tight space again.

    I began laying track yesterday and have about 1/4 of the mainline done but have not ran DCC power to it yet although I did hook up my DC transformer to run an old DC engine on it to check continuity. I have not soldered the joints yet...that comes later but the train ran fairly well as is.

    Thanks for all your suggestions and ideas...keep them coming.

  7. theBear

    theBear Member


    You'll like DCC.

    I just got back into the hobby after a long absence, so I decided to start fresh in that area. I'm in the planing stages on a layout and all over the map on the other aspects of the hobby. I just completed re trucking/wheeling/coupling 23 of my old pieces of rolling stock, I have a few more to go. I also have a nice 4-8-4 that can really pull that I've just got to get a decoder inside of.

    If you are doing it new upgrade the wiring and play it SAFE, remember a short must trip the breakers and leave everything undamaged. If you abide by the rule that the wiring system must safely carry the maximum current produced by the power supply then things will work out fine. For a five amp supply #14 for the bus and enough feeders off of it to the track to add up to at least what the #14 bus can handle. In the case of #22 that would be 7 feeders per electrical block (allowing for turntables and reversing loops here).
  8. dhutch

    dhutch Member

    i dont know about the US wire sizes - but for my DCC layout im using heavy multi strand wire thats 1.5mm dia, which i use in a ring main under the track, which is conected to the track by 0.8mm wires evey meter or so along - this seems to work, and im happy that its up to the job

  9. theBear

    theBear Member

    1.5 mm is between AWG15 and 14 and the 0.8 mm is between AWG20 and 21 this should just about hit the 5.0 amp setup spot on.
  10. kchronister

    kchronister Member

    HO gauge: I use 12 ga. for the power bus and 20 ga. for the feeders (about every 6 feet).
  11. brianhok

    brianhok New Member

    I will be running 12ga bus and 18ga feeders.

    Question: Can you run the bus wires parallel to each other or twist them around each other?
  12. kchronister

    kchronister Member

    You can do either. Loosely twisting them (I've heard one twist per foot) is supposed to reduce any chance of interference.

  13. theBear

    theBear Member

    You can even tie them into knots as long as:

    1: You can tell which wire is which.


    2: They are insulated from each other.

    We don't need shorts now that winter is approaching in the northern hemisphere, and the folks south of north don't want to look at our hairy legs [​IMG]
  14. Matthyro

    Matthyro Will always be re-membered

    I run my buss wires parallel and haven't experienced any problems.
  15. vanda32547

    vanda32547 Member

    I temporarily hooked up my MRC Prodigy Advance DCC system (in 1 place only) to my mainline with 22 gauge wire to a curved terminal section of atlas track attached to the end of a siding just to check things out.

    To my amazement my Atlas engine responded perfectly. However my Broadway Limited would not. (too far from the power source I think) although it did make all the cool sounds and responded to all the accessory sound buttons... it just would not run.

    I am sure once I install my power bus and feeders to various sections of the layout all will be perfect. I was just impatient to check it out. Also none of my rail joints have been soldered yet. Want to make sure I am happy with the track positions first.

    DCC is SO COOL I am loving it so far and I am just getting started.

  16. dhutch

    dhutch Member

    yeah, it ammazing waht works

    - but at the same time, it will work using heavy cableing for DCC, and long runs

    - its just saves headacks later!!


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