For the first/last pole, do like the prototype does. When the lines turn, and apparently every few miles "just cause", the wires will be terminated at the pole, with a horizontal insulator on each side, then there's a loop of wire, often with a vertical insulator, connecting the two sides.
On a model, the visible lines could terminate the same way, with a stub of rigid material going into the backdrop, or sticking out towards the aisle.
Randy: It wasn't anywhere near as complicated, just a line of wooden poles with crossarms, but the local power companies that supplied the Milwaukee also ran commercial lines along their electrified division. Even today, with the tracks long gone, the power lines are still there, following the old right-of-way.
