One thing that trips people up is the difference between 15-amp and 20-amp outlets, aka receptacles. They sell both kinds at home centers and hardware stores, so how do you know which one goes where?

Behind the wall, 15-amp outlets typically connect to 14-gauge wires, while a 20-amp uses thicker 12- or 10-gauge wires. These wires correspond to the amount of current each circuit can safely handle.