Overpitched,
WAC charts only show the Transmission power lines on them, and I believe this was a smaller one, possibly an 11KV line. If accounts are correct then one doesn't expect the to be at 150' AGL.
As a pilot having been too close to the bloody things while out there working, I only know that no matter how careful one is there are those power lines that can take you by surprise. If he was travelling to the east, as he departed Parkes, then at that time of the day the sun would have been a concideration in him not seeing the line during his scan.
RIP S.T.
VX.