The third prong on an outlet is commonly referred to as ‘the ground’, and it provides an alternate path for electricity that may stray from an appliance or product.This is an important safety feature that has been required since about 1962.
But, what can you do about old 2-wire nongrounding-type receptacles, where no ground exists in the outlet box? 210-7(d)(3) permits any of the following installations when replacing a 2-wire ungrounded receptacle: (a) Replace it with another 2-wire receptacle; (b) Replace it with a GFCI-type receptacle and mark the receptacle with the words “No Equipment Ground;” or (c) Replace it with a grounding-type receptacle protected by a GFCI device (circuit breaker or receptacle).
The ungrounded outlets are easily distinguishable by their two slot configuration verses the newer grounded type of outlets that have the two slots with a hole (ground socket) centered under the slots.
For this particular article, I will refer to these outlets as UNGROUNDED outlets and GROUNDED outlets.
While it is not usually required to upgrade ungrounded outlets in your home today, it is still a good idea because a properly wired home is a much safer home for you and your family. The problems for owners of older homes start when two wire ungrounded outlets are removed and substituted with the grounded type outlets without the necessary rewiring that will add a ground wire to the newly installed grounded type outlet.
People tend to replace 2 wire ungrounded outlets with ungrounded type outlets in order to establish a more convenient outlet for their three prong appliances.