A polarized plug is found at the end of an electrical cord on an appliance and on some heavy-duty indoor and outdoor extension cords. Electrical appliances have specific certification guidelines that must be followed to comply with safety regulations in the United States and Canada. Having a polarized plug is one such safety feature that is required by law.
A polarized plug is easily distinguishable from other plugs because the blade on one side is wider than the other. Consequently, a polarized plug can only be inserted into an electrical outlet one way.
Using a polarized plug reduces the risk of electrical shock and fire. According to the Consumer Product Safety, electrical plugs and cords are involved in nearly 20 percent of all electrical wiring fires in the home each year.
Do not force a polarized plug into a non-polarized electrical outlet, as this defeats the safety feature and could be dangerous. Some homes, especially older residences, do not have polarized wall outlets. Older outlets in these homes should be replaced with polarized outlets by a licensed electrician.