Note the open switch on each of the three lines. (The rotating bits on the top of the middle insulators are disconnected from the lines on each side. These are operated by a (locked) handle at ground level, which is connected to the top by the metal pipe running up the left side of the pole.)
On another block, somewhere, there must be a matching high-voltage circuit that's currently connected. When the utility people need to work on one line, they can throw these big switches, and work on the disconnected line.
BTW, what is it with me, power lines, and the moon?
Details: Nikon 18-70mm, 48mm, f/11, 1/100s, ISO 200, crop.
Note: I'm currently way behind on daily posting, having been away, and not in the posting 'mood', for a while. I'll be spending the next while catching up.