Why Are Receptacles Installed Ground Down?
It is mostly about familiarity and custom. When we start doing anything, we prefer to stay at it. Seeing a ground-down receptacle “face” is comforting since it is what we have always known. Ground-up receptacles stand out because they are less common.
Manufacturing and design innovation may also play an influence. When you reach for and grab a cord, the natural way to hold the plug is with the flat side up and beneath your thumb. Inserting the plug into a ground-down receptacle does not require flipping it around in your palm, indicating that manufacturers anticipate a ground-down orientation.
Is One Way Better Than the Other?
Not according to the NEC. Both approaches are safe and effective as long as they are properly wired. Grounding-type receptacles with three prongs must be connected to the green or bare equipment grounding conductor. In the event of a short circuit or other malfunction, the EGC returns the abnormal current to the electrical panel, allowing the breaker to trip. The EGC operates regardless of how the receptacle is angled.
Older homes wired with knob-and-tube will not have an EGC. You can tell because the receptacles only have two slots: hot and neutral. If you have these (like I did for years), consider replacing them with a GFCI.
Of course, the NEC isn’t the only code that matters. Your local electrical and construction codes may specify how you should position receptacles. If you have any questions, contact your community or a professional electrician in your area.
