In article ,
says...

Many primary-feed industrial locations ran at 480/277 for lighting and motors. I remember when I was in school our drafting studio was in a former factory right on the Schuylkill in Center City. Wallplate voltage was 130V, lighting was 277, and even the ceiling fans and exhaust fans were 480V. What made it even more interesting
was that the primary service to the building was 4-wire, 2-phase converted to three-phase using 'Scott-Connected' transformers, AKA 'Scott-T' transformers. https://en.wikipedia.org/wiki/Scott-T_transformer

In the studio, there were all kinds of warning stickers on the receptacles stating that they were at an actual 130V. And for those of us with drafting lights, lamps were supplied.




I worked in a large plant as an electrician/instrument technician.
Dealt alot with the 480 3 phase motors and heater circuits. We fed the
floursescent tubes with one phase to neutral for 277 volts. We did
reduce the voltage to 120 volts for the common recepticals.

There was just a small ammount of the 208 3 phase circuits. We had just
a few 120 volt filament bulb lights so did not get into those very much.

Then we got in some 380 volt ( I think that is the voltage) 3 phase
stuff from Europe. We were not told that and me and another were trying
to set up a heater controler of about 200 amps. Could not get the
thing to set up right and them measured the primary voltage and it was
about 100 volts low. After some checking found out the voltage fed to
the building was only around 380 volts for that european equipment.