The answer to 'what size outlet installation do I need' is that the size of electrical outlet you need depends on the power requirements of the appliances or devices you'll be using. Most standard household outlets are 120-volt, 15-amp outlets, which can handle the power needs of most common household items like lamps, TVs, and small appliances.
However, for larger appliances like ovens, dryers, or air conditioners, you may need a 240-volt, 30-amp or 50-amp outlet. These higher-capacity outlets require a dedicated circuit and should be installed by a licensed electrician to ensure they are wired correctly and safely.