Large Wooden H-Frame
Twin timber poles and a pair of crossarms carrying a double circuit: two sub-transmission lines on a single frame, spanning farther than any lone pole could hold. The heavy structure of the early grid, cut from the tallest, straightest trees available.
Insulators do the talking
The H-frame was a way to keep working the tower form at a size I could handle, and like the distribution pole it rewards repetition: two poles under their crossarms become one bay, and a run of them becomes a line. What I kept coming back to, though, were the insulators. At this scale they finally had room to read as real hardware, and they are my favorite part of the model, the detail that makes the whole frame look energized rather than just wooden. I wanted the design to carry that: a simple, repeatable timber structure whose insulators do the talking.
What I was really after was a classic lattice tower, but the same instinct that started me on the distribution pole applied here: build up to it. The wooden H-frame was the next rung, a bigger structure than the pole but still forgiving enough to get right. Its size turned out to be a quiet bonus. Without planning it, the frame lands close to the scale of my larger equipment like the high-voltage transformer and the capacitor bank, so they finally look like they belong in the same world. The crossarms were the fight: the spacing a convincing H-frame wants falls just between the tolerances the bricks give you, so getting the two poles, the crossarms, and the insulators to sit true took more trial-and-error than anything else on the model. It is also the first design I built in quantity. There are three of them standing on my office shelf at work, which is about the most honest proof I have that the thing is genuinely repeatable. The classic lattice tower is still the goal, and this one got me closer to it.
Before steel
Where a single pole reached the next street, the H-frame reached the next town. Two timber poles under a pair of crossarms, it carried a double circuit farther than the founding grid had any right to ask of wood, and did it decades before steel made the same span easy. BEPCO's records note that the hard part was rarely the engineering but the sourcing: a structure this size wanted trees tall and straight enough to be worth the felling, and the Company spent nearly as much time in the forest as on the line. Its Instruction Booklet reads, in places, more like a timber order than a wiring diagram.