SASless, Spot on.
Crab, any unimproved LZ yes. same class 1 approach.
No map has 100% of wires. Telegrapgh lines will and have taken down helicopters. So have logging line and other "lines" that are temporary and would not be on your map. Powerlines are not typicaly hot, but can be under intense loads. The infrared thing would not work on denergized lines, telegraph/telephone lines, guy wires, loging lines etc. Anything that only works 95% of the time gives a false sense of security and actually detracts from safety, thats why every catalog based wire detection system or map has failed.