https://www.youtube.com/watch?v=II9GZrKztXQ
When I heard power lines, for some reason one scene from Patlabor came to mind.
It's the quintessential Tokyo city view from the window, and the quintessential view inside a window from the city. Outside there are power lines. You cannot avoid them. And looking in, you see the tatami flooring and dudes in their underwear.
I thought it might have been Patlabor 2, but it was the original movie. So that's 1989. Both movies are staples of Japanese anime.
But power lines can also be found in episode 1 of the TV series.
https://www.youtube.com/watch?v=OFTs97NpnUo
So my short answer would be Patlabor, but that's just from my own memory.
I think the commonality here is that the power lines are used to portray a sense of scale for the robots. A kid growing up in Tokyo knows exactly how high those lines are.