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Earlier today I noticed a light go out, and of course everything else that was in the room went off as well. I went to the breaker box to check and see if the one for that room had tripped, but it had not.

I checked one of the outlets with an outlet tester, and it is telling me that the hot/ground wires are reversed. I turned off the breaker and replaced the outlet. Turned it back on, and I am still getting the same message on the tester.

One thing I noticed was if I turn off the light switch to the room, the tester message changes from "hot/ground reversed" to "open neutral".

Also, I tested the outlet with a multi-meter, and it is getting 120 volts on the hot side, but it is also getting 60-80 volts on the neutral wire. Any ideas as to what could be going on?

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    And are the lights still out? You start the story with lights, and segue to an outlet? Maybe the outlet was wired (incorrectly) to the light switch? You're going to need to do a lot more work to figure this out. Also, it's not impossible to get voltage on neutral, it's called stray voltage, and it's hard to measure properly unless your multimeter has a low-impedance setting.
    – Ariel
    Jan 21 at 2:32
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    Compare voltage from neural to hot, neutral to ground, and hot to ground. If the voltage on neutral was "real" it would show up when you compare to hot, and you compare hot to ground to check that hot has a normal 120.
    – Ariel
    Jan 21 at 2:34
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    On those 3-light testers, the lights are useful, but the label describing what they mean is total lies. (or to be more precise, it assumes wiring mistakes in brand new construction, not wiring failures in old work that was correctly wired). Jan 21 at 4:51

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Those outlet testers can be horribly misleading, there are multiple different faults that could cause any particular combination of lights and the ones they print on them are often not the most likely faults.

AFAICT, when the outlet tester says "hot ground reverse" what it really means is that voltage was detected between hot and ground, and between neutral and ground, but not between hot and neutral.

That could be caused by a hot ground reversal like the people writing the tester instructions think, but wires don't just magically swap themselves. A real hot-ground reversal might be possible if some numpty had just wired things up but it's highly unlikely to be found in an existing installation.

In reality the indication is far more likely to be caused by a broken neutral wire in combination with some load in the circuit pulling the broken neutral up to the hot voltage.

When you turn the light off you remove the load, the tester now sees a different combination of voltages and (most likely correctly) indicates an open neutral.

Measuring a voltage that is neither close to zero nor full mains voltage is also a telltale sign of a wire that is not connected to anything and floating around.

In summary it's pretty clear you do have an open neutral, now you just have to find it :/ start inspecting everything on the circuit and the panel feeding the circuit looking for neutral conductors that are not securely in a terminal/splice.

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    Thanks for the best description yet of why those 3-light testers act that way. Their labels are tuned for catching wiring mistakes in new work, which is their target market. A pass-fail for GC's to know if the electrical was done right. Jan 21 at 4:59
  • Thank you everyone for the responses. I need to add a little information to the problem: the first three lights in the circuit are functioning properly. When it gets to the 4th light switch, that is the one that causes the change on the tester lights. Is it possible that the problem is stemming from that 4th light? Jan 21 at 14:38
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    @Mrbungledisco you are most likely correct that the issue stems from miswiring or a loose at or after the 4th switch. That would be the best place to start to look for the problem. If you check over all that wiring and are still having issues, it could be that the connection is wrong/broken somewhere between the 3rd and 4th switches. That would be the next place to check.
    – FreeMan
    Jan 21 at 15:26
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    It turned out to be a loose neutral at the 3rd light switch, which connects to the rest of the outlets afterwards. What a nightmare lol, I literally had every outlet out of the wall and the light fixtures out of the ceiling. Going to take a break for a while now and get to putting everything back together shortly. Thank you again everyone! Jan 21 at 17:55
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Your multimeter readings can be misleading, especially if it is a digital one. You can pick up parasitic current/voltages- so even a 'dead' switched outlet can show some voltage. An analog meter won't. And I had to have this demonstrated to me to believe it.

ASSUMING YOU ARE COMFORTABLE AND SAFE WORKING WITH ELECTRICAL CIRCUITS- if not, call an electrician.

(I believe so as you turned off the breaker and changed the outlet, but it needs to be said)

I would start checking each outlet on that circuit individually. If you know where things come into the room at, power wise, I'd start disconnecting there and working your way backwards. You could have a neutral wire pop free if they were pushed in.

I am more concerned that the breaker blew- something should have 'snapped' in there for you to locate on.

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