Utilities: Utility pole with yellow cable encasing

The problem when photographing something as complicated as a utility pole is that it isn’t just a big pole in the ground. When you look at a utility pole you’ll see there’s stuff all over it, stuff that I have no idea what it is or what it’s called.

There’s this cable running down to the ground, in this photo. It has yellow encasing– insulation? –around it. Is the cable a grounding wire or just some sort of a support cable?

I have no idea, so my title for this photo reflects my lack knowledge. I tried looking it up, but didn’t find an answer.

But I do think it’s a cool photo, full of angles and lines and that yellow that just about smacks you in the eye. : )