We recently received a control rack that we built years ago (before I worked here) for a customer (auto parts supplier). Our task was to do some evaluation on a software problem they were having. There were a couple of LARGE power supplies in it (besides the computer equipment) that were each on a dedicated circuit internally. We shipped it with a suitably sized SO cord on it. This is how they hooked it up in their plant. It gets better. A guy here mentioned he was called out there a couple of years ago because the "system didn't work" and found one of the wire nuts had come loose. He showed them the problem, their electrician twisted it back on, our guy turned around and left and they paid us for a service call.