Any ideas as to what this would be used for?

Home was built in 1987. Garage had a few GFCI protected outlets. There was one separate outlet that was only 2 prong (located about 3 feet away from a GFCI outlet). It showed a weak signal with my light tester. When I put a volt meter on it, it showed 1Volt.

  1. What is a 2 prong outlet doing in this house/garage?
  2. What would a 1 volt circuit be useful for?
    I’m stumped.
    The only thing I can think of is the homeowner replaced a faulty GFCI with a an old 2 prong outlet they had laying around. There was subsequently a fault. And now it only shows 1 volt after the fault.



A photo would help. Was it a standard NEMA electrical device? If not could be for a roof antenna.

A picture would help greatly.

see added pics to original post

Wild thought but I have seen it done many times. Wired for a speaker system. :roll:

My guess?
Dead, decommissioned outlet putting out a “ghost”, induced voltage…

Typically a multimeter can show a small voltage when there is an open neutral.

In my experience though, that voltage is around 4-6 volts…
1 volt just b/c of an open neutral is too little, IMHO…
I’m sticking with my theory of a dead outlet and induced voltage :slight_smile:

The OP is using a $5 meter, hardly accurate. But I would say induced voltage too…not hot.

It’s definitely a cheap (it was free from northern tool, actually! hahaha) meter, but completely accurate when tested next to my other higher dollar meters. No reason not to believe it. Dollar cost of the meter is not a factor.

I wondered how long it would take for someone to comment on my free meter!
The voltage actually fluctuated from about .8 to 1.2v. But just happened to read 1v when I snapped the pic. As far as it being a stereo speaker line, interesting. Now that you mention that I have heard of this being done. The home was a foreclosure and had no stereo equipment or anything left behind, but could definitely have been used for that.

Shouldn’t you be able to verify if it’s phantom voltage by applying some load to it and seeing if it disappears?

Yeah. I used a light tester (since it was only a 2 prong), and it lit it up, and it was enough voltage to keep it lit, but just much dimmer than 120v. So that’s what caused me to be curious and put the voltmeter on it.

Light tester may not be big enough of a load, but 1 volt is not that big of a voltage to put a load on, so testing it could be hard.
In my limited experience, these things are best researched at by tracing the cables through the junction boxes, which is way outside the scope of a home inspection.

I would defer to a sparky…
This could be nothing, i.e. “phantom voltage”, but it could be a loose connection arcing or glowing somewhere.
Better safe, especially now that you’ve pointed it out.

What is the input impedance of the VOM?