While charging the vehicle at a reduced rate (30 amps out of a 40 amp maximum) there was a thermal event in the outlet box that the Mobile Charger Connect was plugged into. There were no witnesses to the event, but it was later noticed that the wall around the outlet was blackened and one prong of the plug had melted the housing of the plug along with the receptacle. The Mobile Charger Connect had previously shown a high temperature warning, so the operating current was reduced from 40 to 30 amps at the direction of service personnel at the dealership. The Mobile Charger Connect was plugged into the specified NEMA 14-50 receptacle that has been in use for the entire duration of ownership.