Homes built through the 1950s had ungrounded (2-prong) receptacles. That was the norm then but is an inconvenience today.
Chester County Home Inspections often find outlets with Open Ground faults or other anomalies in these old homes. That’s because homeowners often simply install 3-prong outlets in the place of the 2-pronged ones, which leaves the grounding conductor open. Here our electric tester shows open ground in a house that does not have ground wiring but has grounded outlets.
Can you address the ungrounded receptacles issue without having to re-wire the house? Yes. You can use GFCI receptacles, as the National Electrical Code (NEC) says in section 406.3(D) paragraph (3) Non-Grounding-Type Receptacles. Here is that section of the code with excess text removed for simplicity:
Non-grounded receptacles shall be permitted to be replaced with:
(a) a non-grounded receptacle;
(b) a GFCI type of receptacle. These receptacles shall be marked “No Equipment Ground”; or
(c) grounding-type receptacle where supplied through a GFCI. Grounding-type receptacles supplied through the GFCI shall be marked “GFCI Protected” and “No Equipment Ground”…
Option A allows you to replace a broken one with a new one. Oh, OK.
Option B is simple – replace the ungrounded 2-prong with a GFCI receptacle AND properly label it as ungrounded.
Option C requires clarification. You can replace the 2-prong with a 3-prong receptacle provided that the branch circuit is supplied through and thereby protected by GFCI. There are two ways to protect the branch circuit.
But first, what is a branch circuit, you might ask? For simplicity, it is the wiring from a breaker on the main service panel to a room. A branch circuit serves multiple receptacles which are typically wired in series, a.k.a. daisy-chained. You could protect the branch in two ways: (1) with a GFCI circuit breaker in the panel to protect the entire branch, or (2) with a GFCI receptacle device to protect part of the branch. In the latter scenario, all receptacles in the daisy-chain after the GFCI are protected also.
There’s one more requirement of that NEC code that must be followed, which is that all ungrounded outlets protected by a GFCI must be labeled accordingly. It works like this. If the whole branch is protected by a GFCI circuit breaker in the panel, then each receptacle on the branch must be labeled “GFCI Protected”, and “No Equipment Ground”. If only a part of that a branch is protected by a GFCI receptacle device, then it must be labeled “No Equipment Ground”, and all outlets that come after that must have both labels.
You might have guessed this: it’s hard to figure out the daisy-chain sequence of receptacles on the branch. Also, there are complexities if the house is wired with shared neutrals, and additional limitations not listed in this short overview. It’s best to leave this job to a professional electrician.
Caveat #1: even when done correctly, the GFCI will still show open ground with a wiring tester. That’s because it remains ungrounded, although safe from shock. It could only be deemed correct with the proper labels; without it, we must surmise that it is improperly wired.
Caveat #2: watch out for double GFCIs on one branch line, it has ramifications that could drive you nuts trying to find the reason for dead outlets. That’s a topic for a different blog.
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Ungrounded outlets cannot be fixed without adding ground, but you have inexpensive options to use 3-prong outlets when your house only has 2-prongs. Want to know more? OHSA explains. Need an inspection of your home? Schedule online now, or contact us at (484) 212-1600.