Most homes are wired with both 15-amp and 20-amp receptacles. 15-amp outlets have a u-shaped grounding hole and two slots. 20-amp receptacles have a horizontal slot that branches off from the vertical slots. 20-amp outlets work with appliances, such as microwaves, and must operate on a 20-amp circuit.
Some duplex outlets allow for back wiring instead of side wiring because it is generally a much simpler process. However, back wiring is not as secure as a side wiring connection. We recommend installing a duplex receptacle with both type of connectors.
The Americans with Disabilities Act (ADA) highlights in section 4.2.5 and 4.2.6 that outlets must be at least 15 feet above the floor. Switches and outlets should not be more than 48-54 feet.