A neighborhood mystery solved?

I may have mentioned that we have some crappy neighbors at the old house. My pal Samir moved out in the summer of 2008, and it was purchased for use as a rental. The first round of tenants were painfully hip and occasionally rowdy, but generally tolerable. Their replacements.... well, they're something else. They've had a car up on blocks since they arrived in November. They used to pile up garbage and junk outside. They've got some weird pavilion set up on the front lawn. It's the sort of thing that makes you want a HOA (which the new neighborhood has). They have 2 adults and 6 kids between 2 and 14 living in a 1700 sf 4-bedroom. It's nuts.

Anyway. That's not the mystery. For a few weeks, we've been hearing some kind of engine coming from their garage. I've been wondering what it is. Since the man of the house is something of a fixer, I figured it was an air compressor for running pneumatic tools. Still, it was strange how often it was on. At night, for instance, or when nobody seemed to be home. How much compressed air does one man need?

The other day, as we were cleaning out the old house, I heard a clue, perhaps the only necessary clue. A friend of theirs that I'd seen before came to visit. As I was throwing away trash (trying to set a good example) or something like that, I overheard the friend ask a single question (imagine the appropriate Texas redneck accent): "So whaddya'll gotta do to get the electricity turned back on?"