Light-duty extension cords are those that resemble lamp wire cord. These cords should never be used with anything other than very light-duty devices. They are especially dangerous to use with space heaters and other heat-generating appliances, such as toasters or clothes irons, which draw heavy electrical loads

A 16-gauge extension cord is for light duty applications (holiday lights, portable fans, hedge trimmers, etc.). A 14-gauge cord is for medium duty applications (lawnmowers, power drills, table saws, etc.).

Light duty cords are usually constructed with a two-prong plug, while heavy-duty comes in a three-prong plug. The additional prong is allocated for grounding to reduce electrical shock. In contrast, the two-prong cord is suitable for lamps and small appliances for home use.