My advice is to get a pair of pants that are comfortable and durable. You’re going to be working outside a lot, with tools and machinery, and the location always varies. You could be on your back in a parking garage, hanging off the side of a building, out in the woods messing with a substation, and so on. Also, rerouting power from municipal outlets to locations that want power but don’t want the grid is totally illegal, so you might have to do some running in those pants too.
If a size is not listed, it is sold out.