Inside the body of the plug, the cord's wires are fastened to blades to enable electric power to pass to the cord from the receptacle outlet. When inserted into an outlet, the blades become energized. Three-prong plugs include a ground pin that connects exposed metal parts of an appliance to the residential wiring system ground. Two-prong plugs do not have a grounding pin. Removing this pin could lead to electrical shock.
Polarization helps reduce the potential for shock.
Older homes may not have polarized receptacle outlets. If not, the receptacles will not accept polarized plugs. A qualified electrician should replace the old receptacles and put in wiring consistent with polarization. Do not risk injury by modifying or forcing polarized plug blades to fit into a non-polarized outlet. They offer convenience and are easy to use on a temporary basis.