A worker unplugs the unit while it is still operating drawing a potentially deadly arc which would not happen if they had simply turned off the main disconnect switch when disconnecting a big portable pump or electric welder or big mixer
It is an accident waiting to happen and are totally avoidable simply by just shutting off the disconnect . But people get busy and forget and flash crack boom.
Well one company Meltric has developed a self ejecting plug which helps to prevent this from happening .
I have been encouraging my customers to switch over to this plug and receptacle style to help prevent accidents in their facility and many are doing so. the units are expensive but one cost eliminated is since the plugs can serve as disconnect a separate disconnect does not need to be installed.