Outlet tester results for open ground on mixed circuit

Question

I have a US house built in 1958 that has been remodeled in many stages over the years. I recently tested a circuit that included ungrounded outlets in the old part of the house. A number of years ago, we remodeled a bathroom and had the electrician replace a couple of ungrounded outlets on that circuit with what were supposedly grounded outlets (with a GFCI thrown in). I checked both those outlets and there is a ground wire connected to the outlet and going into the wall.

My Sperry (plug-in) tester shows an open ground. Do these testers always show an open ground when a circuit doesn't have a ground back to the panel?

Another couple of notes/questions:

• On one outlet, my Sperry non-contact tester lights up when I get close to it. This works as expected on other outlets (on other circuits). When I pull that outlet out of the wall and test the neutral and hot wires, hot lights up (as expected), neutral does not. Does this indicate a problem with that particular outlet unit or just the general unreliability of non-contact testers? My tester had the same result with two different outlets hooked up to these wires.
• Going back to those "grounded" outlets mentioned above, a multimeter shows about 116V across hot/neutral, but zero from neutral/ground and hot/ground. That seems to indicate that despite the presence of a ground wire, that ground doesn't appear to actually be connected to anything. Is that a reasonable conclusion?

Answer 1

You're about correct on the ground wire being floating loose at the other end

The other end of that ground wire is indeed most likely floating loose; this is OK if the outlet is GFCI protected, though, as the GFCI will trip and save you if something plugged into it tries to bite you.

As to the NCV tester...

Since the neutral is bonded to ground at the main panel, a normally functioning neutral will not light up a NCV tester (you can test this by sticking the tip of the tester into the neutral slot on a normally wired outlet). It's neither a problem with the tester, nor the outlet.

Answer 2

This is an extension to @ThreePhaseEel.

Your first problem is that you have a 1958 house that was remodeled in many stages over the years. This means you house will fall under several different revisions of the code. The part of the 1958 house that was never remodeled still falls under the NEC it was wired under. Meaning those receptacles are ungrounded.

When you say:

A number of years ago, we remodeled a bathroom and had the electrician replace a couple of ungrounded outlets on that circuit with what were supposedly grounded outlets (with a GFCI thrown in)

Your electrical contractor should have brought the new area up to the new code (probably the 2014 NEC). Regardless, it is apparent that he simply tried to bring the circuits already in place up to the standard as outlined in NEC Article 406.3. This Article allowed ungrounded receptacles to be replace with grounded reseptacle devices and attached to a GFCI protected circuit and still not have a ground. Chances are that the ground wire you see in the device box is not connected to any ground in the system. It just happens to be there because you can't buy stock cable without a ground any more.

For more information about 406.3 click on this link: http://www.myintegrityhomeinspection.com/Realtor%20Area/2_prong_outlet_replacement_GFCI.pdf. It is quite descriptive and will help you understand what is happening.

So make sure the GFCI protection is in place and working, and then label the bathroom receptacles as required by code and you should be good to go.

PS. About the NCV Tester: you might invest in a outlet tester with GFCI testing also. Then you might go around your dwelling and survey all of the receptacles for other problems. They are about $8.00. Her's a linlk: https://www.homedepot.com/p/Gardner-Bender-Outlet-and-GFCI-Tester-GFI-3501/202867890?MERCH=REC-_-PIPHorizontal2_rr--206029151--202867890-_-N

Good luck and stay safe.