[i]Just a thought, but in round figures 1050V would be the phase-to-phase voltage on a wye system with 600V phase-to-neutral -- 600 x SQRT(3) = 1039V. 600V is a standard voltage in a few places -- Canada for a start, so perhaps there's a link?[/]
600V is a standard voltage in Canada, but it's a phase-to-phase voltage. The phase-to-neutral voltage on these systems in 347V. We also have 480/277V systems, but these tend to be older systems or equipment imported from the U.S.