[jnaas2]

You cant install a grounded receptacle on a two wire system, the bare wire is a equipment ground and a lot of appliances need that to killl the power in case of a shortcircuit. Code does allow a gfi to be installed instead of the 2 prong plug, because a gfi measures the amount of electricity going out verses what comes back and will kill the power in the case of a ground fault and not kill you