Preparing Switches for Constant Voltage

Like your other accessories, Lionel switches (and other brands as well) will operate much more reliably when taken off of track power and fed with a constant voltage accessory supply. We recommend 14 Volts AC for switches as well as your other accessories.

Running on fixed 14 Volts ensures that:

  • Your switches will operate at the same speed every time, regardless of how fast your train is moving.
  • Switches will have plenty of power to throw without excessive force on the points.
  • Light bulbs in switchstands will glow longer and cooler – preventing the plastic lanterns from melting.

If your transformers are in phase, then all you need to do is connect the AC Hot wire from the switch machine to your accessory power supply and you can continue to use the connection to the rails for the ground. For most Lionel switches, this is an easy process.



Remove the jumper and attach your new wire where the red wire is seen here.

To convert a FasTrack switch (any size) to constant voltage, all you need is a small screwdriver and a length of wire.

  1. On the underside of the switch, you will see a set of screw terminals. Two of these are labeled “AUX IN” and “TRACK JUMPER.” They are connected by a small metal bus.
  2. Using a small screwdriver, simply remove the bus between those contacts.
  3. Connect a new wire from the “AUX IN” terminal to your AC Hot connection or bus wire from your fixed 14V power supply. The wire can be tucked into the channel along with the others.

That’s it!



All you need to do is used the plug supplied to convert O-31 switches.

An O-31 and O-72 switch is even easier. Each O-31 switch includes and auxiliary power supply plug. Simply attach the wire from your power supply to this plug and plug it into the side of the switch box. The plug is tapered to push the track connection aside and make the direct link to your accessory power supply.


Unfortunately, the O-27 switch requires a little more work as it is not designed to be converted to accessory power. Don’t worry, this is still a great first-time wiring project.

O-27 Switch

The O-27 switch will require a little more work, but it is still a project a beginner can do.

  1. Remove the brown cover from the switch machine by removing the screw and lifting.
  2. Locate the wire in the center of the twin coil switch motor and lift it away from the coils. This is the AC Hot connection. Leave the outer two wires alone – these go to ground (outside rails.)
  3. Cut this wire leaving a tail from the coils long enough to attach a new feeder.
  4. Make sure the other end of the wire is not exposed (this goes to the center rail) and tuck it away.
  5. Remove the insulation and splice your new wire onto the tail from the motors. Insulate the entire connection.
  6. You’ll have to either drill a hole through the base or in the side of the machine cover to get this wire out of the switch motor.
  7. Attach the other end of your new wire to the accessory power supply.
  8. Attach the cover on the switch.

The entire process will take only a few minutes – even less after you’ve done a few and have all your tools and materials handy.

To see all of these conversions in detail, just watch this video: [youtube=]

19 thoughts on “Preparing Switches for Constant Voltage

  1. I purchased Fastrack Command Control switches. I will hook them to direct voltage. Do I have to hook them to a ASC? I will be using Legacy controller.
    They come with the lever wires attached. Since I will not need the lever to operate the switch do I just remove the wires from the switch?

    • You won’t need the ASC as the switch already has a command control receiver installed. Just program the switch to the address desired following the instructions in the manual. If you won’t be using the other controller, you may remove the wires from the switch all together. Like the conventional switches, we do recommend switching them to run off of a separate constant voltage power supply. There are instructions for this in the manual as well, or you can use the information here on this page as this process is the same for both conventional and command control switches.

  2. By performing this modification on O-27 switches, is there any change to the functionality of the non-derailing feature ?

  3. Forgive the beginner blunder but I followed instructions to modify 2 fast track switches to constant voltage but found that a ground wire to the AUX GRND was also required to illuminate switch lights and active switch via remote. Unfortunately after reinstallation found that the entire track and the switches is now powered on via the constant voltage accessories outputs from the CW-80. Perhaps I need to modify the switch grounding beyond the instructions above?

  4. for additional context to question above running single track layout for 1 train with 1 CW-80 transformer wired directly to track (red on center/ground on outer rail)…i.e. no wired bus/feeders or phased power to ~14′ X 5′ oval with 2 switches.

    • If you follow the instructions here, you should not have any problems. I would however recommend going back and putting in a bus wire and a few feeders. On an oval that size, you are probably seeing some noticeable voltage drop at the far end of the layout.

  5. After modifying 027 turnouts for constant 14 v power, is there any change to connecting the three wires for the controlling switches?

  6. I have switched a 6-65122 O-27 switch to constant voltage. The problem I am have it when the trains runs over the control rails (two rails with insulated pins), it completes a circuit causing the switch to change position and derail the train. Any ideas how to fix this so it doesn’t happen?

  7. I switched a Lionel 6-65122 to a constant 14 volts. The problem I am having in when the train runs over the control rails (rails with insulated pins), it causes the switch to solenoid to move the metal pin and derails the train. Any idea what is causing this?

    • It sounds like you have the automatic rails wired in reverse. The points of the switch should throw in alignment with your train, not against it. Try switching the wires to your switch and see if that helps.

  8. When installing a Fastrack switch for command control and constant voltage, as pictured above, can the manual remote wires be unhooked?

  9. I have several 5121’s made in Hong Kong. The wiring on the coils seems to be different. Any suggestions on how to proceed if you can’t get to the center coil wires?

  10. I have the older lionel 0-42remote, 0-27 gauge.. I have a problem when the engine crosses the switch they short out, any solution ?They are the 6-65168 series

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