Wiring Turnouts on the Main Line

There are frequent questions from individuals building modules on how to wire turnouts on the main line. In this discussion, it helps to recognize that protecting the integrity of the main line is a priority. If a member’s branch line has a problem, it is only a local issue. If the problem shorts out the main line, then train operations for everyone are affected.

The basic NTRAK requirements that need to be met for main line turnouts:

· All branch lines must be able to be isolated from the main line. A branch line can be powered from the main line, but there must be a way to isolate it electrically if there is a problem.
· Electrical separation must be maintained between the three main lines, so a pair of turnouts used for a crossover need to have an insulated joiner in each of the divergent rails.

· Power routing through the points is not allowed on the main line, so an additional power connection must be provided on the divergent side of the turnout. You may power route on the branch line.

· If an alternate power source is to be used on the branch line it must be connected in a way that prevents connecting to the main line.

The internal electrical connections are different in each model turnout. For example, the PECO Insulfrog, PECO Electrofrog, and Atlas turnouts are wired differently internally and provide different challenges. A PECO Insulfrog will be used as the example in the following discussion:

o a short siding without a lot of electrical junk.” At least one switch will be required to provide power to the branch line from the main line to meet the criteria that the branch line can be isolated. Besides, a switch is very useful, allowing a locomotive to be parked and isolated on the siding while others are running on the main line. The switch can be located under the layout if desired. Figure 1 illustrates this minimal arrangement.

Figure 1:  Simplest approach to wiring.




Jim Davis,
May 27, 2014, 6:43 PM