I recently bought an LG electric ventless dryer to put in my garage. I thought it used 120 volt but actually 240 volt. Fortunately there was already a 240 volt outlet in the garage for EV charger use in the future. So I spent some time to study the basics of the US domestic electrical power to make sure I wouldn’t make trivial mistakes when extending the 240 volt outlet for the dryer use.
Where does 240 volt come from?
There are 3 lines connected from the street (or the power plant) to a home: two live lines (or hot lines) and one neutral line. Both two live lines carry single phase 120 volt but have opposite phase. It means the voltage between two live lines is 240, and the voltage between either live lines and the neutral line is 120. The neutral line doesn’t carry live current. It is a path to flow the 120v current back to the power plant.
What is the ground line used for?
The ground line is used to create an escape path to flow the electricity that is not supposed to exist on an object (e.g., a metal appliance surface touching live line), instead of someone who is touch the object to get a electrical shock. Although the name has “ground”, the purpose is NOT leading the current to the ground, but still back to the power plant. So eventually all ground lines connect to the neutral line from the power plant.
The neutral line from the power plant connects to earth through a ground rod too. This is NOT to make the whole…
