I'm working at a plant where in the olden times they use 480 single phase to power 277 volts power lighting circuits (no neutral), just 480 volt to ground. Note the ground wire is insulated back to the panel (kinda of acting like a neutral). I know this is bogus today but was it ever legal ? I'm talking some 40 years ago. Are these types of installations grandfathered? Or is this just a royal screw up?