Hello to all. I need to size a transformer for a small project. Well to be honest, I'm not 100% percent sure that my calculations are correct. I need to install a transformer in a remote location to power up a "high water level" security system. (simply to notify me that i have dewatering pump problems) I currently only have 480 VAC 3 phase at the site. I need approx. 5-6 amps at 120 VAC. I would like a little bit of extra, maybe 10 amps.

Can someone please show me the proper calculations to verify my thinking? Thank you