ECN Forum Forums General Topics of the Trade General Discussion Area How to get this to work?

I'm looking for alternative solution to this problem. I've got this little mig welder that uses 120v and I need to get it on a roof top for small welding jobs on HVAC equipment. My problem is the thing pulls 20+ amps and most of the power on the equipment disconnects is 480 3phase 277 to ground. I'm looking for an alternative to a transformer.