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New Member
New guy doing a new N layout. I've decided on Peco switches because of the positive spring action on the points. What is the purpose of the "frog" and the significance of them being insulated or not? Which do I want??

I plan on running DC (not DCC) on two seperate mainlines. If I can't get all the necessary elevations right, I may have to use turnouts to keep the two trains routed properly. That is not my first choice, however, as I want to be able to enjoy seeing two separate trains running independently, and not be constantly fiddling with turnout switches. I wish to have all turnouts powered.

Any tips are appreciated!
Greg in Dallas


Southern Railway lives on
The frog is where the two rails cross. The insulated or not is if you are going to be DCC or not. I don't ahve DCC myself so I don't know the specifics but somebody here will reply that knows more.


New Member
The frog is the part where the left and right rails will intersect on the diverging route. There has to be a way to prevent the "+" and "-" rails from shorting. This is done 2 ways. (either insulated or non-insulated frogs) There have always been insulated and non-insulated frogs. (Long before there was DCC)

Insulated fogs are generally a dead spot where there is no electricity available to reach the wheels.

Non-insulated or “Powered” frogs are live and will supply electricity to the wheels as they roll over the frog. When the turnout is selected straight or diverging, the frog will change polarity to match the route selected.

If you use DC then definitely go with non-insulated frogs.


1) short wheelbase locos won’t stall
2) power routing (turnout will direct or cut-off electrical power to the siding) (note: Peco "Insulfrog" are also power routed)


1) Additional gaps or insulated joiners required
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New Member
Frog thing....


Thanks much for the frog lesson! Seems to me one would want to use powered turnouts regardless. Why would one wish to cut power to the track unless you are wanting to make a siding dead. But then, how do you get power to the engine to run back onto the siding to retrieve what was left there?


New Member
With "Route selective" turnouts, the siding is only dead when the turnout is selected for the "main" route. When you select the "siding" route, it becomes powered and the main will not be powered.

Here are some helpful links:

Now, after talking about all of this, there is another kind of turnout which matches the above types physically, but is electrically different. Those listed above have the siding electrically live with the same power as the mainline unless an electrical toggle switch is installed. The other kind of turnout is called a selective turnout. It selects the way the power is routed by which way it is thrown. When it is thrown for the siding, the siding is powered and the straight route goes dead. When it is set for the main, the siding is dead. This creates a different wiring situation, and you must be certain that the rails leading out of the turnout are properly insulated to prevent shorts. This is no problem at all, but it is different from the turnouts that you will usually use on your first layout.

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