I've been training with my new P3P for almost 20 flights now. Mostly doing VLOS practicing at the park getting a hang of it. Today I decided to do some range testing. I planned it all out a very controlled test environment. A long wide canal bank that goes for many miles in a sparse rural area. That way I would never fly above people or private property and if I had to ditch or or land I have a good area to do and would make recovery easy enough with my vehicle. I drove up and down it once to check it out, being careful to note any power lines or obstacles. I looked at google earth and discovered 1 location where power lines crossed the canal, made note of it and decided I would not go below 150ft for safety even though the canal bank was always clear, I knew of those lines. Well my range tests went way better than expected. I made it out almost to 13,000 ft after 5 consecutive battery runs getting further and further each time, sort of creeping out further and further to ensure nothing unexpected happens. Where I went wrong was that I hold only scouted out in my vehicle to 10,000ft or so, but I had studied the rest in google earth, saw no obstacles and figured that was good enough. Turns out there are a pair of small domestic power lines that cross the canal near 11Kft. Thinking the way was clear I got cocky and decided to see how low my altitude could go and still hold signal at that distance. Got down to around 60ft and still had full signal. Bear in mind the SS you see was when I was cruising along at 50mph riding a tail wind in ATTI mode. Saw what looked to be power lines flash by very close on my FPV screen. Had a sinking feeling that I almost had a disaster. Reviewed the footage after and sure enough.. I must have came within 10ft of them. Thought I had scouted the area and covered all contingencies. Didn't think it would ever happen to me because I am very responsible and careful. Could have been a disaster. All further testing will be done in an open field. After it happened my hands were almost shaking and I packed it up and went home. Could not even fly anymore, had a sick feeling. BTW it did not interrupt my signal at all, in case anyone was curious. Anyone else have close calls with power lines?