[pubema]

I need your help.

The current power for my living room was out. I checked the main panel and reset every breakers. However the living room still was without power.

I used the DMM to test several receptacles in the living room area and here what I found:
1) Phase (hot) to neutral was less than 1v
2) Phase to ground 120.9V
3) Neutral to ground 119.7V

Can you tell me what happened here? How do I troubleshoot the problem?

Greatly appreciate your help. Thank you in advance

[47884788]

Sounds like you lost the neutral leg coming in from outside

[ballengerb1]

Definitely not a lost netral, so don't go there. Go back to your pnael and test between your hots and your nuetrals are they correct at the panel? In you 3 scenarios #2 is normal

[pubema]

Hello ballengerb1 and 47884788,

I will test the main panel when I get home.

Here is the side note: I had the same problem happened last year when the weather was extreme cold. My living room was out of power. I reset the breakers and tested the living room and it did not work. So I set out to work and no body was home. When I got home later that night the power just came back itself. I guessed something was weird but it worked and I just ignored the problem.

Now it just happened again. I also found out that my living room and my bed room shares the same circuit because when I flipped the breaker, both my living room and bed room have no power and I did verify them with the DMM and voltage sensor. Well when I reset the breaker to on and now my bed room has power, part of the bed room's receptacles and the living room still have the same problem as I mentioned previously.

Question, do you think that I have a bleeding power or short circuit somewhere inside the conduits? I know something must not be right, but I could not logically understand what happened?

Any good suggestions? Thanks in advance.

[stanfortyman]

This IS an open neutral, but likely only on this one circuit. You need to check every box on the circuit. The problem will be in the first bad receptacle or the last working one.

[mcad]

This IS an open neutral, but likely only on this one circuit. You need to check every box on the circuit. The problem will be in the first bad receptacle or the last working one.

I agree. I just ran into a similar problem at a customers home. After a few hours, I found a loose wire nut on the neutrals in a junction box in the basement. What made it obvious that it was a loose neutral somewhere to me was that I had 120 volts at the ground and hot, but only 90 volts at the neutral to hot. Unfortunately, a loose neutral can be hard to find.
Another thing to consider is that a lot of times, the connections to the receptacles are not pigtailed. So if the power comes into an outlet and it malfunctions, it could stop everything down the line from working. Though if this was the case, I doubt that it would begin to work again like you mentioned.

[pubema]

Thank you very much for all your suggestions.

As I am writing right now, the power of my living resumed itself. I just got home from work and after having the dinner, the power just came up itself even before I attempted to check the main panel again.

What happened?? Hopefully no aliens are here to play with it :).

I partially agreed that it could be an open neutral. But how could it got reconnected itself?

Now this could be a dumb question, if it is an open neutral, why it is hot (119.7v)? I thought when it opened that means it should have zero voltage. Please educate me.

If I want to check for open neutral, can I use tone generator to check for the signal from the receptacle to the main panel or to other receptacle like we do with the network cable tracing?

Thank you in advance for all your suggestions. Happy Holidays.

[Stratmando]

I also believe it is also an open neutral on one circuit.
If the neutral is open any where on circuit, then power will go from the hot wire, through a load(Light, Motor, anything)and out the neutral.
The neutral is intermiddent, and can be caused by heat/cold(expanding contracting), could be by backstabbing wire in receptacle.
I would turn off that breaker, See what all went out, and check those boxes.
Try turning off all lights and unplug everything on that circuit, that shoud remove the voltage from the Neutral.

[pubema]

It was an open neutral.

I solved the problem. What I did was:
Test continuity on every receptacles on the same circuit branch that gave me problem. I ran the 3-prongs cable from one receptacle to another and start testing each connector for continuity between two receptacles. I repeated this process over again to the next neighbor receptacles and so on. Finally I found the broken neutral feeding line. I fixed it and no more problem. I am a happy camper.

Thanks all for your suggestion.