22 gauge wire

Discussion in 'HO Scale Model Trains' started by taylor_up_bnsf, Nov 20, 2008.

  1. pgandw

    pgandw Active Member

    The gauge of wire needed depends on 3 things:

    • acceptable voltage drop - in DCC around 0.7 volts maximum is recommended. This is only an issue if the bus is too small a gauge or on large layouts with long wire runs - or you have too many rail joiners between feeders.
    • current expected to be passing through feeder. This depends on the current draw of your engines and lighted cars, and how far apart your feeders are spaced. Typically, 0.5 amps per locomotive (in HO), and 0.1 amps per lighted passenger car (2 12V bulbs). If feeders are spaced close enough that only one train will be drawing through any given feeder at a time, then the feeder is handling less than 1 amp.
    • possible short circuit current through feeder. This is probably the determining factor for wire gauge. Since short circuits typically happen with something bridging the 2 parallel exposed conductors (the rails), the wiring to the rails must be capable of passing the current rating of the circuit breaker without overheating. If you have a 5 amp DCC system with feeders space a ways apart, then each feeder must be able to handle at least 3 amps (which is where the 22 gauge feeder minimum comes in). If feeders are more closely spaced so they will work in parallel, or your DCC system is set to a lower current rating, then smaller wire can be used.
    Combining 2 26 gauge wires gives you the same current capacity as a single 22 gauge wire. But both wires have to have solid connections. Twisting wire pairs is not an issue in DCC for the track/power bus. The track rails aren't twisted. Twisting sometimes is recommended on longer runs of the throttle bus (links plug in plates for throttles).

    DC wiring seldom deals with currents as large as DCC. Typically, power packs are rated at 2 amps or less - often less than 1 amp. I used 26 gauge magnet wire very successfully for feeders on my small DC layouts, with a 16 gauge common rail bus. The magnet wire has a varnish insulation, which makes it very unobtrusive. Because I didn't use rail joiners, every piece of rail had to have a feeder of its own. The same system could work for DCC if the circuit breaker was dialed downed to 1.5 amps (26 gauge wire is rated at 1.8 amps). Since I don't run triple-headed or long passenger trains, 1.5 amps is sufficient in any power zone with up to 2 trains.

    Last comment: the best test for adequacy of DCC wiring is to lay a quarter across the track at various places (those with the least wiring). If the circuit breaker pops instantaneously, you are good to go. If it doesn't, add or beef up the wiring until it does.

    my thoughts, your choices
  2. TCH

    TCH Member

    thanks for the replies to my question.

    my apologies to Taylor up bnsf for not starting a new thread
  3. tomustang

    tomustang Has Entered.

    If you haven't already looked at home depot/lowes/radioshack/local hardware stores/local hobby shops etc.. you can look online at MSC or a Grainger catalog.

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