Hi,
I am trying when the current NEMA 250V and 277V receptacle configurations (6-20R, 6-30R, 7-20R, 7-30R) were adopted.
Does anyone know if the adopted configurations for 250V and 277V were different 20 to 30 years ago?
Does anyone know when approved applications for 277V receptacles/plugs changed?
I cannot provide specific details, but the matter I am looking into may involve a misapplication of a 250V plug with a 277V source.
Any information or suggestions about where to find more information would be appreciated.