What Is That Third Prong For?
DID YOU KNOW… … that two-prong receptacles may be grounded? Often, people associate the third prong on an electrical receptacle as an indicator of whether the receptacle is grounded or not. In fact, the third prong has NOTHING to do with such a determination. The true purpose of the third prong is to extend the system ground to a device which may need it, which happens to correspond to the third prong on the power cord. The plug is inserted into the receptacle, and this third prong provides the electrical path for the system ground to be connected to the device or appliance. But, to have this accomplished, the SYSTEM must be grounded and there needs to be a path available in the branch distribution cabling, so as to extend the ground to the receptacle in question. This can only be verified via examination of the distribution system, which includes cabling, electrical panels, and electrical feeder and grounding cables into the dwelling.
