Open neutral or something else?

Last night me and the wife where whatching tv in the living room. Out of nowhere the living room started erratically cycling power about 3-4 times. (lights, ceiling fan, tv, etc.) End result being my living room is now dead...

ALL other circuits (rooms) in my home where completly unaffected and are fine. It was only my living room experiencing the freak out.

I went straight to the panel. Breaker was not tripped, so I cycled it which was no fix... I took my digital multimeter and I had 120v out the breaker with it closed and none with it open as it should.

Checking a few outlets in my living room show 120v on both sides of the outlet. (hot to ground / neutral to ground)

I replaced all the wall plates when I first bought the home and I do have the screw down connections and NOT the push-lock style. I also pulled a few plates off last nigh and did not see any loose, broken or shorted connections.

I left the breaker off and I am at work now. When I get home I will follow the hot wire from the breaker to the bundle in the panel and see from the bundle where the nuetral is connected to the panels block. Hopefully it will be there. A quick once over last night did not show anything obvious.

Any ideas?

Your voltage readings are indicating an open neutral. It could be in the panel or any one of the device boxes on the circuit. If part of the circuit is still working it could be in a working box as well. If you know the route the cabling takes the problem is in the first not working box or last working box.
I would start by checking the box closest to the panel since cable usually run away from the panel.

Yeah thats what I figured. When I get home I will start at the panel and work my way down the line. Hopefully it is something simple. Appreciate the reply!

The loads that are plugged in in your living room are why you are reading 120v on the open neutral.
With everything unplugged from that branch you may read 60v on the neutral with the reading depending on what kind of meter you have, the length of the branch wiring and if the cable has a ground conductor (which yours does). It's a Phantom Voltage.

If you find an appliance that operates normally on that branch, the open in the neutral is between the living room and that appliance.

Wuzzat? said:

The loads that are plugged in in your living room are why you are reading 120v on the open neutral.
With everything unplugged from that branch you may read 60v on the neutral with the reading depending on what kind of meter you have, the length of the branch wiring and if the cable has a ground conductor (which yours does). It's a Phantom Voltage.

If you find an appliance that operates normally on that branch, the open in the neutral is between the living room and that appliance.

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He gets 120 on the neutral because a light or something is completing the loop

Yes, the plugged-in loads are supplying the current to the multimeter. With nothing plugged in and an open neutral he should read a Phantom Voltage.

With a heavy load like a hair dryer instead of a multimeter, it should operate between hot and ground but hardly work between neutral and ground even though the open circuit voltage on each with respect to ground is similar. It's because the source resistance of the hot lead is about a half ohm but the source resistance of the open neutral through the loads is several ohms.

I know you love your multi meter, But let's get down to solving the problem. With the breaker turned on and with a light turned on at the other end of the run. If neutral is reading 120, the opening is closer to the breaker, if it reads close to zero it is further away. That is all you really have to know and on a bad day you find a bad wire between two boxes and open a wall to find where the squirles live and chew wires.

Can't wait to hear how this resolves ... dead mouse in the wall?

Alright guys found the issue yesterday after work. I took the cover off the panel and traced the hot (black) wire from the breaker to the romex bundle at the top; then followed the neutral (white) wire back down from that bundle to the panels neutral/ground block. Sure as anyhting the neutral wire was burnt up about 3" back from the tip. I was able to simply/easily pull it out of the block. I cut the "dead" stuff off, strip and reconnected to a new terminal lug. Good to go!

I heard the 60hz is a "slow pulse" and actually induces and slight vibration that over time will do exactly what happened... The house was built in 03. I know hospitals have a time complience/preventitive maintenance schedule to tighten them down ever so often. I did just that and tighten ALL my neutrals. To my surpise a few needed tightning.

Learn something everday! Thanks all!

Oh and every outlet on that circuit was reading 120v on both when the problem was an issue. I unlugged everything from all the outlets on that circuit as well with the same readings; although my can lights and ceiling fan are also on that circuit. All other circuits in my home read 120v on hot, 0v on neutral and 120v between the two. Now the "problem" circuit reads as it should. :beer:

So you have a loose connection that is connected until it warms up. Have you got pigtails in the boxes or are all the wires just stabbed into the back of the outlets?

While you were in there did you torque the other whites? If one is loose others could be.

^ Yes sir, " I did just that and tighten ALL my neutrals. To my surpise a few needed tightning."

^ " I replaced all the wall plates when I first bought the home and I do have the screw down connections and NOT the push-lock style." So, all my outlets and switches are the hook/pig tail, screw down type.

The problem was at my breaker panel itself in the garage. On each side of the inside of my panel there are neutral/grounding block terminal strips for all my homes circuits. (insert wire in the terminal block then screw down fastner) The neutral wire from that particular circuit was loose in that block causing the failure in that circuit.

Sounds good. Oldog will send you a case of beer.:rofl:

Joeb1983 said:

burnt up about 3" back from the tip. I was able to simply/easily pull it out of the block.

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High contact resistance connection due to low contact pressure. Five watts may not be enough to heat up the neutral busbar at your connection but you could have had 10x this much power, up to maybe 300w.

Joeb1983 said:

I heard the 60hz is a "slow pulse" and actually induces and slight vibration that over time will do exactly what happened... The house was built in 03. I know hospitals have a time complience/preventitive maintenance schedule to tighten them down ever so often. I did just that and tighten ALL my neutrals. To my surprise a few needed tightening!

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This is an excellent practice ... Don't have to kill it by over-tightening, but firm retightening is a great preventative. Nicely done! :

You are very luck to have found the problem in the loadcenter . Many time , you have to spend a lot of time and effort searching for the defect . :-(

Since you do not usually know the rout the Romex takes from the loadcenter , to device , to device , to device .....

As I think someone stated , it is often in the last non-dead receptacle . Another problem , a home owner often forgets where all the receptacles are . And it ends up being behind the heaviest piece of furniture in the house . :-(

More often than not , it is in a receptacle , than in a switch box or lighting box . Since receptacles often carry heavier current loads .

Good job !

God bless
Wyr

WyrTwister said:

Since receptacles often carry heavier current loads .

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?
The current in a series circuit, i.e.,
-receptacle-switch-breaker-
is the same.

Still, these may fail at a higher rate for other reasons, probably mechanical wear.

BTW, IMHO, I think God damns more than He or She blesses.

BTW, IMHO, I think God damns more than He or She blesses.

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That's why we have to ask for the better choice

slownsteady said:

That's why we have to ask for the better choice

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What should we ask for for this bunch
http://en.wikipedia.org/wiki/Malignant_narcissism
which includes more than a few politicians?