Talk: PECO Electrofrog

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A message posted on by an MR Editor:

RE: turnouts Reply by Steven Otte

I'm answering this very question in an upcoming edition of "Ask MR." Here's what I wrote...

The short answer is: Either. The choice depends on how you prefer to wire your turnouts. You can spot the difference between the two types of Peco turnouts by looking at the closure rails that converge on the frog.

On an Insulfrog, the closure rails are solid, and there’s a short section of insulating plastic rail where they meet the frog. The tip of the frog itself is likewise non-conductive plastic. Locomotives run on Insulfrog turnouts should have long electrical pickup wheelbases; engines that pick up power on only a few wheels, like some older steam locomotive models, can stall on these turnouts. But if you run diesels that pick up power from both trucks, or steamers with pickups on the tender as well as the drivers, you have little to worry about from an Insulfrog.

An Electrofrog has small gaps in the closure rails, about an inch before the frog. Underneath, small jumper wires bridge that gap. That means that out of the box, it seems like Electrofrogs work like Insulfrogs: the closure rails get power from the points, which get it from contacting the stock rails when they are lined in either direction. But on an Electro­frog, the entire frog, closure rail, and point assembly is one electrical unit. This means that unlike an Insulfrog, on which a closure rail is powered only if its point is contacting its stock rail, on an Electrofrog, both closure rails and points are always powered the same polarity as the stock rail the one point is touching. This is fine if your locomotives’ wheels are all perfectly in gauge. But if any of those wheels, or metal wheels on your rolling stock, are a little tight back-to-back, it’s possible that a wheel can touch both a stock rail and an open point rail simultaneously, causing a short. This can’t happen on an Insulfrog, which is why some people regard them as more “DCC-friendly.”

But there’s a reason for those little gaps on the Electrofrog turnouts. Electrofrogs come with a leader wire attached to the bottom of the frog itself. There’s also a gap in the plastic ties underneath, two ties before the gap in the rails topside. If you cut the jumper wires, the points/closure rails and the frogs become separate electrical units. Solder some jumper wires across the gaps in the ties, joining each closure rail to its adjacent stock rail, and you not only give the points a much more reliable power connection, but also, you guarantee that each point and closure rail will always be the same polarity as its adjacent stock rail — eliminating the possibility of shorts at the points.

But then the frog is dead, right? That’s where the frog’s leader wire comes in. Attach it to the switched contacts of a turnout motor like a Tortoise by Circuitron, or to a DCC-aware polarity switching circuit like the Tam Valley Frog Juicer, and your frog will automatically switch to the right polarity for whichever way the route is lined. It’s a little more wiring work, but you need never worry about turnout shorts again.