Home Up Overview Insulfrog Electrofrog New Code 83





ElectroFrog is Peco's term for a Live (powered) Frog turnout, what some people call power-routing. With most live-frog turnouts, there are three issues you need to be aware of in order to use them successfully.

  1. Wheel flange clearance between the stock rail and open point
  2. Frog and frog rail changing polarity
  3. Point vibration causing power/signal problem

Most so called DCC friendly turnouts address issue 1. Some point out issue 2 and how to cope with it. Most do not even mention issue 3.

Most Peco ElectroFrog turnouts can be used right out of the box with no concern about issues 1) and 3). Only the occasional special need will require some modification. And even then, the modification will be easy because of the way Peco ElectroFrog turnouts are made. Issue #2 is the only issue to be concerned about with Peco ElectroFrog turnouts (and all live-frog turnouts). Peco InsulFrog turnouts don't even have that issue to be concerned about. All of these will be discussed below.



1. Wheel flange clearance between the stock rail and open point



With power routing turnouts, both points usually carry the same polarity. Illustration 1 shows how the power flows on a normal power routing turnout. Polarity is shown with Red and Green lines drawn over the rails.

You can see that the open point has the opposite polarity. If the clearance between the stock rail and open point is not enough to allow the wheel flange to go through without touching the point, you will have a short circuit. But you can see with the Peco turnout above that there is plenty of clearance even for the fattest wheel flange.

Some manufacturers design their turnouts with this clearance so close that a short circuit is all but unavoidable (thus requiring modification to the turnout to make it work properly with DCC).



Note: These short circuits generally don't matter when operating with DC analog because the typical power pack doesn't put out enough current to harm anything (they generally put out only enough power to run one train). When a short circuit happens, the power pack simply puts out all the power it can for the short period of time the short circuit is occurring, and no harm is done. But with DCC having enough current on the rails to run ALL the trains, a short circuit can cause harm. Therefore, Short-Circuit Protection is built into boosters. When a short circuit occurs, the booster shuts down and the trains stop.



2. Frog and frog rail changing polarity



Some people call this Power Routing, some call it Live Frog. Illustration 1, above, shows how a power- routing turnout is powered when closed for the through route. Illustration 2 shows how it is powered when thrown for the divergent route.



You can see that all the track pieces in the middle changed from green to red. With Peco InsulFrog turnouts, all the track pieces stay the same regardless of which way the turnout is set.

The reason this is called power routing is that it can make the route not set for dead. In the illustration above, you can see that both rails of the through route have the same polarity. This means a loco can't run (the through route is dead). With DC analog, people used this to be able to run a loco onto a siding to let a train pass. But with DCC, this is not needed (simply because each engineer is controlling their trains independently regardless of track power).





With DCC, it's more important to have good solid track wiring to all rails. Running power through the point contacts is not as positive as connecting the siding directly to the track power bus. So to accommodate a power-routing turnout with DCC, the frog rails must be isolated from the rails that join to them, as shown in Illustration 3.

Insuring that the frog rails are isolated from the adjoining rail is all most people ever have to do to use most Peco ElectroFrog products. However, some ElectroFrog products require a little additional work, which will be discussed later in this section.



3. Point vibration causing power/signal problem



With DCC, power to the points is far more important than power to the frog. The typical turnout provides power to the points via slip joints, brass contacts, or some other method. The problem is, when your loco is traversing the points, the points vibrate. And with just that little bit of movement, power is interrupted. It's only for just a nano second, but just long enough to mess with the signals. Unlike a spot of dirt on the rail, a whole truck of your loco will be on it. This means that 1/2 of your power pickup for that side is gone for that nano second. At first blush, this wouldn't seem too much of a problem, and usually isn't - after all, you still have as much power in the other truck as locos use to have. But, with so many more things that DCC does than you could do before, this kind of power interruption can cause spikes that can be disruptive.

Peco turnout points get power from two contacts. But more importantly, these contacts are more positive than on most other turnouts.

  1. The points make contact with the stock rails like all others. But, only Peco has a spring that forces the points tightly to the stock rails. Besides providing good solid electrical contact, it also resists vibration caused from locos running on it.
  2. The points also have wipers which make contact to the bottom of the stock rail. So, with the spring holding the point tightly against the stock rail, and the wiper making contact to the bottom of the stock rail, it has two points of contact for power transfer at that end of the point.
  3. The points also have a unique pivot connection to the closure rail. It doesn't just ride on the pivot pad as points do on some turnouts. It has two tabs that stick through a hole in the pad, and bend over to secure it to the pad. This provides contact from the tabs to the hole in the pad, as well as between the top of the pad and bottom of the point (again, two (not one) point of contact from that end). Since this is where the frog and frog rails get their power, it's important that these pivot points have good contact to provide good solid power to the frog and frog rails






It's unlikely you'll need to modify any Peco ElectroFrog turnout. However, if you do, it's usually very easy. First, the points are secured to a plastic throw bar. If you need to isolate the points for whatever reason, all you have to do is make a cut in each of the closure rails, as shown in Illustration 4.



At that point you'll have to feed power to the frog rails through an independent switch (like many other turnouts require). Looking at Illustration 5, you can see wire connections between the closure rails and frog rails.



All you have to do to feed power to the frog, frog rails, and closure rails on the frog side of the cuts is to connect a feeder to the wire spot indicated above. You can't see it in the photo above, but the tie going down from the feeder connection is hollowed out to accommodate bringing the feeder out from under the turnout if desired.



Special ElectroFrog Considerations



Some ElectroFrog products have frogs that need to be powered irrespective to a single set of turnout points: 3-Way Turnouts, Crossings, Slips, and Crossovers (Scissor Crossing). Refer to those pages for information about them.

Again, if using Peco InsulFrog turnouts, none of these issues are of concern.



   Back Home Up Next

Send mail to sales@sodigi.com with questions or comments about this web site. 

Copyright 1998 through 2014

SOUTHERN DIGITAL Railroad Hobbies (770) 929-1888  Fax (770) 679-0300   

Last modified:  May 23, 2016