Pauluk:
277 volt fixtures here are rare but they do exist... Often its a case where a building contains a lot of machinery designed for use in the U.S.A and a 277Y / 480V supply is used.
In my area (New England), for other than dwelling units 277 lighting is far and away the most common voltage for lighting circuits.
If it's a commercial building (unless it is small) the service will be 480Y/277.
Outdoor lighting is often run line to line at 480 volt.
