Finally!  I still can't believe it, but I have the lamp units back in place and the wiring is done - AND it's correct this time!  So, without further delay, here is my pride and joy:

Now all I need to do is put it up in the back yard... and connect to a power source.

I had always wondered how the power got to signals on signal bridges - or to any other signal, for that matter.  I found out when I went to get my signal; in fact I got an eight foot long piece of the answer: very thick, very heavy cable.   The cable - shown in the following pictures - is made by Okonite, which specializes in cable for railroad and airport use.

My next question was how do they know which conductor is which?  I was baffled - until I was stripping the insulation off the wires to get the copper (hey - I didn't steal the cable, and I couldn't use it for my purposes, so why not?) and I noticed, in faint yellow print, a pound sign followed by a numeral.  Yep: they had numbered the individual conductors so that, by exposing the individual conductors at each end of the cable, they would know that they were working with the same conductor at the signal and at the power source.  Cool!