Dana,
"Listed tools...shall not be required to be grounded where protected by a system of double insulation or its equivalent."
FYI - virtually any tool/piece of equipment you'd ever want to plug into your ungrounded 3-prong plug [406.3D] falls into this category. ...this includes your refrigerators, freezers, air conditioners, blah, blah, blah.
I've never seen a double insulated refrigerator, freezer, or air conditioner. If it has a 3 wire cord it is not double insulated.
Don
