Wiring basics - help needed

Discussion in 'FAQs' started by eddie, Dec 19, 2006.

  1. eddie

    eddie New Member

    I am using atlas 3 rail track. When I connect a transformed which terminal connects to the middle rail? Also, when I install a siding which rail should have the insulted connector so I can control it independent of the main track. I also find the terminology of common confusing. A simple explanation would be appreciated/
  2. N Gauger

    N Gauger 1:20.3 Train Addict

  3. cidchase

    cidchase Active Member

    Hi eddie,:wave:
    Your transformer puts out AC. Your three-rail trains also use AC. Common-rail wiring
    is a term applied to DC trains, not something you have to worry about. The polarity of
    the terminals on an AC power pack doesn't matter. Isolating gaps can be placed in the
    center rail. Isolating the outer rails is probably redundant, but if required, both outer rails
    should be gapped. I think the only real thing to watch out for is preventing a short in a
    reverse loop.:)

    Best of Luck with the layout!!:thumb: :thumb:
  4. pgandw

    pgandw Active Member

    Unfortunately, it varies as to which post to connect to the center rail from transformer to transformer. You want to use the variable tap of the transformer to the center rail, because some accessories and transformers use a common post (sometimes called ground) for the fixed accessory voltages and the outside rails of the track. The instruction sheet that came (or didn't come) with your transformer will tell you which to connect to which. Perhaps if you can tell us which transformer(s) you have, we can help with the correct wiring.

    The previous posters are not so familiar with 3 rail AC wiring. The insulating pins to create electrical blocks for independent track control go in the center rail. I assume you are using more than 1 transformer if you are setting up electrical track blocks. If so, you want to "phase" the 2 transformers so that when the insulating pins are spanned by locomotive center rail pickups, the resulting momentary (we hope) fault current is fairly small.

    The older, tubular track used the metal ties to electrically tie the 2 outside rails together. Unfortunately, I don't know whether Atlas track ties the 2 outside rails together or not (I suspect it doesn't), and my Atlas 3 rail track is packed up for moving. If it is not done at the factory, you will want to wire both outside rails to the same transformer post for better electrical pickup, especially on curves and switches.

    Please don't hesitate to ask further questions - you are not the only who is learning 3 rail AC wiring. Provide as much detail as you can, and if you prefer you can send a PM.

    yours in wiring
  5. cidchase

    cidchase Active Member

    Hey thanx, Fred! Did not know that. As long as it is a fact that all the transformers used
    will always have the same phasing on the tap, then the outer rails can be considered
    "common rails" and gapping them serves no purpose. When you say "phasing" the
    transformers, assuming that the tap needs to go to the center rail, does that imply that
    the phasing can be swapped? If the 110 plugs are not polarized (probably not possible
    on modern equipment), then that requires swapping conductors somewhere inside the
    enclosure, no?

    Also, eddie, further consideration reveals that the AC reverse loop does not cause polarity
    problems as it does in DC, and does not require a gap at all! Makes life easier...:D :D
  6. 60103

    60103 Pooh Bah

    Cid: the phasing is done by turning one of the plugs around where it goes into the wall. The reason is that the AC from the transformer goes up down up down ... but if the plug is backward it goes down up. You can tell if the phasing is out if something crossing between transformers creates a big spark. (or use an AC voltmeter -- see if the difference is near 0 or near 24 -30)
    On Lionel's old transformers, the single train ones had the U oost to go to the center rail and the A post to the outside rail. On the big ones like the ZW, there are 4 U posts that go to the outside rails while the ABCD posts go to different sections of the center rail (4 different trains). Try the Olsen Toy trains site for views of the manuals. The newer Lionel transformers have wiring that is a little mixed up. If you have a recent Lionel locomotive, you are wired properly if the whistle button operates the whistle; if it operates the bell you're backward.
  7. cidchase

    cidchase Active Member

    Thanx, David! I just did not think that any device was still being
    sold with a non-polarized plug on it (one which can be turned around). :thumb:
  8. 60103

    60103 Pooh Bah

    Cid: I just checked and our new Lionel CW80 is polarized.

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