Splodge,
When I was doing my low level helicopter mustering training most of the focus was on wind. Not turning downwind in the treetops without sufficient speed/altitude. The only thing I remember being told about wires was to cross them at a pole if possible.
When I did my fixed wing ag training I was taught among other things:
a. Never fly where a powerline could conceivably be strung without determining for certain that one hadn't been. This to include between peaks no matter how remote. Draw a line in your minds eye between the tops and fly over it. After a while it becomes instinctive.
b. I was taught how to check whether a line was high enough to fly under by flying beside it initially. Then, if there is, not to watch it as you go under 'cause you'll tend to pull up into it if you do.
c. A lot of wires are made of aluminium which reflects sunlight well. So if its possible to spray a field so that you only cross the wire flying in one direction. Make it so the sun is behind you (early morning, late afternoon). That way you'll see the wire more easily and if you can see it you've a better chance of not hitting it.
d. Mostly I was taught that they are bloody killers and to take them seriously. This was reinforced on every training sortie.
e. Another hint. When you're driving. Study the wires that you can see beside the road. The orientation of insulators, stay wires, transformers etc; can give vital information about where the actual wires are when you're flying and can't see them as easily. If you can drive in the same area as you fly, make mental notes about where they run. More than once I've known to look for a wire from the air because I've remembered seeing it from the ground.
Find yourself a fixed wing ag-pilot to talk to about wires and how they manage them. Ag-pilots spend most of their working lives down in the wire environment (like many helicopter pilots) yet on a strike per hours exposure basis hit far fewer than any most other sector of GA. There has to be a reason for this and I believe its training.
DB