While in Korea in 75, yes way back then in the old days, I worked in the Air Force as a electronic technician working on lots of things including transmission lines.
Most of the poles were normal size, 50 to 100 ft high but we also had some larger ones that were a real pain. We had boots with steel shanks so we could stand on the bolts, they had steel toes also so needless to say they were heavy. Nothing better for standing on a metal bolt 50ft in the air.
Once up there we would hang a chair with wheels on the lines and travel across to the place on the wires we had to work. Look at the pictures and see the pieces of wire to the left of the pole hanging down? They were called hocks and were connections we had to disconnect or connect to work on the lines. We would check the wires for proper continuity and insulation resistance and fix them as needed. If it was close we would walk the wires, hanging on to the top line to steady our travel and crouch down and do the work.
It was ok being outside but summer was very hot and humid. We would leave early and call it a day by noon. Too hot to work.
One day I was up on the chair and basically stopped sweating, it was to hot and I had let myself get dehydrated. I was getting dizzy so I came down and we headed for camp. We stopped at a stream and laid down in it for a little while and drank some - felt better then.