Normally, tract homes are wired for both the 120 volt (washer and gas dryer controls) and with a 240 volt outlet for an electric dryer. The dryer outlet may not be visible on a casual glance if all the vent ducts, power cords and water lines are obscuring the view. When that happens, people may think the 30 amp double pole breaker is separately feeding the upper and lower outlets of the 120 volt box when that 120 volt box is on its own 20 amp circuit and has nothing to do with the 240 outlet. So, a picture is worth a thousand words.
