How close was the original poster to the power lines?
I was directly underneath the very tall super high voltage lines.
I wasn't in the middle of a span were the lines droop though, I was much closer to a tower. I'd guess the lowest of the lines was more than 100 ft in the air or even 100 above the mast tip. There was no danger of arcing from the lines, but the EM field was being grounded right through the Al mast. It was probably the worst idea ever, and I will never rig that close to power lines again.
It's good you were so far away. Lines like that have a 20+ foot separation distance phase-to-phase because they can arc that far. A fire crew was electrocuted earlier this year when the ladder on their ladder truck got close
to a high voltage wire.
Lesson is: just because you're not touching the wire doesn't mean the wire can zap you.
@dorienc: I used to work at a power plant, too, and never got over the eerie feeling of the hair standing up inside my hard hat when I walked through the switchyard on a humid summer night...