FWIW, GE lists 277V 100-watt medium-base A-21 incandescents on page 17 of
http://www.gelighting.com/na/downloads/02_inc.pdf Apparently UL does not list replacement lamps {or motors for other than NEC chapter 5 hazardous locations}. Isn’t the standard medium-based socket is rated something like 660W/600V?
Imagine a school janitor on a ladder changing a [120V in place of a 277V] lamp in a broom closet overhead fixture. Bulb rupture seems like a strong possibility.
