I got an estimate for installation of a 20kW propane backup generator. He figured the distance he'd have to run a wire (from the generator near the propane supply to a transfer switch he'd install near the main breaker panel) was 120 feet, which seemed way too high an estimate to me when he said it. The written estimate does not include his calculation of this distance. When I measured the distance it was about 72 feet. I emailed him about this descrepancy, and he said he needed to "square off the corners". I have no idea what this means. The path he'd take from the generator to the transfer switch would almost be a straight shot--there may be two "corners"/turns he'd have to make, but by my estimate the total amount of extra distance he'd have to make up would be about 6 feet.

What does this term mean, and why would he need 120 ft of wire to go 72-78 feet? He offered to allow me to purchase the wire and he'd take off that amount from his cost to me. That wouldn't really address the issue.