The 30-amp, 240/250-volt receptacle (third from the left on top in the image above) has two sideways prongs. It’s intended for appliances that need a lot of power. You’ll often find one ...

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.