Stepping up a gear from Simple Pointwork Wiring. A crossover is not really too much of a jump as it is just two points joined together. As long as both frogs are completely isolated, no other special wiring is required. The wiring for the crossover is shown in Fig.4
Tracks A and B can be on the same or different power districts, just make sure the district outputs are correctly phased. i.e. red rail to red rail and black rail to black rail. If you get it wrong the circuit breaker will trip when a locomotive runs from track A to track B. If this happens swap the booster output wires for one of the tracks.
A current limiting lamp can be fitted into the frog wire as shown in Fig.3 on the previous page if you like.
A tandem turnout is slightly different to a three way point. The diverging tracks are staggered. One tracks leaves the main before the other. This is the most common arrangement. The true three way, where the frogs are in line on each side are extremely rare, except with model railway track manufacturers. I have only seen one in real life and it was in industrial trackage in the middle of a Los Angeles street. From the wiring point of view it makes no difference if it’s a tandem or a three way. You will find one switch needs to be set to give one diverging route and both need to be set to give the other. The single switch route, the lower route in Fig.5, drives two frogs, and the upper route drives one frog. If you work through the various combinations in the diagram you can see how it works. In the diagram the straight route is set.
Wiring for double and single slips are treated the same as shown in Fig. 6 and they are really not as complicated as most people think. A double slip is really two points that have been squashed together so point blades and frogs overlap. So to make it work the frog at one end is switched by the contacts on the throwbar at the other end. In the diagram the route is set from B to D. In all this pointwork the wiring is no different to a DC application.