When the humidity is very low inside a building, static electricity can easily build up as people walk across carpeting, dragging their feet, and then touch a piece of furniture, a doorknob, or some other object. When this happens, a discharge of about 40,000 volts can occur in even a small spark jumping from your finger tips. Running a humidifier inside the home during winter can usually keep these “indoor thunderstorms” (a rather exaggerated term) at bay.