I'm going to bed right now, so I cannot check all the details you've gone through but I think we did it the same way. Except that I misunderstood the distance between the 2 wires. I thought they were on the same horizontal line, but if you used Pythagoras to find the distance between them I guess the 2nd wire was on the ground level.
By the way I'm glad you found out the result. Have confidence in yourself.
A pleasure to help.

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Isaac
If the problem is too hard just let the Universe solve it.