Just stumbled onto a great site, which will help you make sense of the various electric power and receptable requirements in countries of the world. It’s called World Electric Power Guide. For example, do you know what countries use this plug/receptacle combination?
According to the site, it’s used in American Samoa, Argentina, Australia, China, El Salvador, Fiji, Guatemala, Kiribati, Nauru, New Zealand, Okinawa, Panama, Papua New Guinea, St. Vincent, Tajikistan, Tonga, Uruguay.
You can easily see how useful this becomes as you’re planning your trips to various countries.