Rick C Shoup wrote:
Pyle light and bracket and steam turbine and piping.The only wiring diagrams I have seen, show a junction box under the rear of the cab roof and a junction box on the upper corner, or at least edge, of the tender front, with a very drooping 'U' of flexible electrical cable between the two boxes, bridging the gap between the tender and the engine. This all looks like the standard electrical boxes we are familiar with for structure wiring, except that these would be weather proofed versions of the square, round and 8-sided boxes; often with a big hex fitting on a screw in/out slug of a cover on the round or eight sided junction box. That can be seen in the detail parts illustrations of Cal-Scale, Kemtron, and PSC electrical boxes.
It seems it is just a big, weather proof extension cord running between the tender and cab, set so that it can be out of most the dust and flying debris of the lower mechanisms running on the rails. If you think about it, they want a very flexible connection between the cab and tender front that can be in the cleanest possible location, yet convenient to disconnect when the loco and tender need to be disconnected for servicing. Not to mention it's the best place to put the connection so that the crew can jiggle the plug if need be. Not that a model can easily show it, but most likely the plug is screwed into place with some sort of collar rather than a household prong plug just sitting in an outlet fitting. A smaller version of a contemporary M.U. cable mount.
The diagram(s) show an electrical conduit running on the underside of the cab roof to the edge of the tender top, back to the marker light electrical sockets, (if removable mounts are used on the marker lights), the backup light mount, and often down to lower rear running board step light fixtures much like you find on today's diesel access steps.
So it's largely a matter of placing the conduit so that you have the shortest run from the cab roof edge to the light fixtures with the conduit running out of the way of operators feet by hugging the edges of the tender body.
I think this is shown in one of the spec diagrams in the Kalmbach Locomotive Cyclopedias in both the 1930-40's edition and the later Loco one steam plan edition. It's a re-print of a standard ARA (?) diagram looking very much like those showing where to mount the ladder and grab irons.
When you think about it, the objective is to use roughly direct runs of wiring and have it both out of the way, sealed to the weather, and still easy to get to for servicing.
The next time you get near an operating tourist steamer, look for the cab to tender electrical connection. That distinctive drooping loop of electrical cable is subtle, but always there if they have rear tender lights.
Milwaukee, Wi, USA