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Discussion Starter · #1 ·
A circuit in my house has stopped working. I have the breaker turned off until I can resolve the problem. The circuit consists of the following:

- 5 electrical outlets
- a single light fixture controlled by a single switch
- two light fixtures controlled by a single switch
- a single light fixture controlled by two 3-way switches (hallway)

Additional background: the house was built in 2001. All outlets, switches and fixtures appear to be from the original construction. We are the third owners (since 2005). No problems on the circuit until it inexplicably stopped working.

With a plug in circuit tester and a digital multimeter, these are my observations:

- in any of the outlets, with all light fixtures switched off, the tester shows "correct" however the middle amber light is half power and flickering, while the right amber light is full power and steady
- with any one or more light fixtures switched on, the tester changes to show "hot/grd reverse" with both the left red light and right amber light glowing full power and steady
- a multimeter at an outlet connected to hot and neutral with all light fixtures switched off reads around 80 volts. Hot to ground reads 124 volts.
- the lamp base in a light fixture reads 0 volts on the multimeter switched off
- with the switches on, this now changes the multimeter readings. Hot to neutral is 0, and hot to ground is around 120 volts. Neutral to ground is around 100 volts. The fixture lamp base reads 20 volts. This last point is from memory. I will reconfirm in daylight.

So far I have taken a new single pole, single throw switch, replaced one existing switch, then tested with no change, and cascaded the removed switch to the other installed switch. Did this to the 3-way switches as well, and to the 3 used outlets out of the 5. Ran out of daylight to get to the other two unused outlets, and highly suspect I won't find anything different once I get to them. In all cases, changed from a backstab installation to screw. Any wiring and connections I see as I open each box appears normal, and connections seem to be tightly wound into the wire nuts.

At a loss as to where to try next once those last two outlets are switched out. I suspect I don't need to look at the fixture connections as one of the failure modes still exist with all light fixtures switched off.
 

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A "Handy Husband"
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Your neutral is open. Start checking at the breaker panel. If that looks good, try to determine the circuit routing and start opening boxes. With your meter you should get a reading (approx.) of zero ohms from ground to neutral.
 

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The problem could be at the last working or first non-working device. Find out what is on the circuit. I would look at the most frequently used receptacles.
 

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Definitely open neutral.
A very common cause of this is the use of back stab connections. If any of the devices are using the back stabs move the wires to the screws.
 

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MEASURE ONCE, CUT TWICE
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Definitely open neutral.
A very common cause of this is the use of back stab connections. If any of the devices are using the back stabs move the wires to the screws.
At a loss as to where to try next once those last two outlets are switched out. I suspect I don't need to look at the fixture connections as one of the failure modes still exist with all light fixtures switched off.
Sounds like my kind of luck.
It will probably be the last outlet you check.
 

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MEASURE ONCE, CUT TWICE
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It is always in the last place you check:smile:

Here's a case of finding something and keep looking for it, ha.....


If it is back stabbed then I would not stop when you find the problem. I would continue to change all the devices to the screw terminals.
 

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A "Handy Husband"
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I suggest replacing the breaker. They're not expensive and do fail on occasion. You didn't change anything before the problem started so why not take that out of the equation.
A failed breaker does not cause an open neutral. And that is what he has.
 
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I have had most things fail in my house, appliances, heating systems, outlets, switches , garage door openers, roofs etc. I have never in 35 years of owning or renting ever had a circuit breaker fail. Every time one trips (which rarely happens I any event) I find a downstream problem which is the culprit.
 

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Discussion Starter · #12 ·
Trouble shooting of the devices have turned up nothing. The remaining two outlets were replaced and converted to screw connections. I then went back to the first device in the circuit, which is the single room light with a switch, opened the box, and determined which wires went/came from where: downstream devices, lights in the ceiling, and the hot line in, and matching neutral. I then disconnected everything downstream, turned the circuit back on, and the same problem still exists.

So on to the breaker, I assume? (Extremely low probability of a damaged wire between the breaker box and this device).
 

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Discussion Starter · #14 ·
I went to the breaker panel. Breaker panel and breakers are Cutler-Hammer. I can see the black wire going into the suspect breaker, and I can see the neutral bar. The multimeter shows 124 volts with the breaker on, and 0 volts when off. I see no way to confirm if neutral is secure in this setup, and the breaker is a DNLP1515. The circuit on the other half of this duplex breaker works just fine.

If it is in fact the wiring, this would be perplexing. The panel is in my basement, and the first device on the circuit is on the top (second) floor, in a room where the other side of the wall is along the stairwell, meaning the wall goes straight down to the main floor on the back side of where the device is located. Logic says that the wire would have been run straight down to the basement within that wall. It is entirely an inside wall, so I can't fathom a rodent being in there, and only there, especially as I have no evidence of them within the house. Removing the downstream wires temporarily from the circuit has eliminated that section as being suspect.

Any idea what the next steps would be?
 

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The circuit on the other half of this duplex breaker works just fine.



Any idea what the next steps would be?
Sounds like a multiwire branch circuit. One neutral sharing two "hots." Can you tell if the two breakers share a neutral? Should be a cable with a black, red, white and bare conductor.
If yes, the problem could be in any of the box's with the "working half." Check the ones closest to the panel first.
 

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The circuit on the other half of this duplex breaker works just fine.



Any idea what the next steps would be?
Sounds like it could be a multiwire branch circuit. One neutral sharing two "hots." Can you tell if the two breakers share a neutral? Should be a cable with a black, red, white and bare conductor.
If yes, the problem could be in any of the box's with the "working half." Check the ones closest to the panel first.
 
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