I am getting ready to hang outdoor string lights in my back yard for which I will need an outdoor extension cord about 20’ in length to reach a GFCI outlet. The string lights have a two-pronged polarized plug which, as far as I know, tells me there is no ground. However, in the safety information for the lights, it states: “Use only two-wire outdoor extension cords that have two-prong grounding plugs and grounding receptacles that accept the appliance’s plug”.
This has me completely baffled. What does that even mean? Is there such a thing as a “two-prong grounding plug”? Aren’t all two-prong plugs by definition ungrounded? And does it even matter if I use a three prong extension cord (as pretty much all outdoor cords are) versus a two prong one? If someone can enlighten me, I would greatly appreciate it.