The MTL switches have nickel-plated cast metal frogs. They are electrically switched so that they are the proper polarity according to the direction of the turnout. They are also physically and electrically connected to the points. The frog and points are electrically isolated from all other trackage. The rails that extend from the frog are tied to the stock rails so that all rails are powered; current will be conducted to and from any of the three tracks connected to the switch, so it doesn't matter where power feeders are located ("power everywhere" design). Hope this information is helpful.
Got the skinny from MTL: frogs are insolated Thanks for your input everyone. While the frog is metal, it is indeed isolated from the connecting tracks. I got this from MTL directly. I assumed that was the case, because upon close inspection, you can see a separation between frog and the connecting tracks, with a small plastic isolator in between them. Steve
