Neutral short - off and on

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  #1  
Old 04-10-12, 09:34 AM
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Neutral short - off and on

The problem occurs within one particular unit of an apartment complex. All other units are fine. The problem has gradually gotten worse. All electricity within the house will flicker on and off. It is most obvious with the lights but TVs, stove, and other appliances are affected as well.

At first, this would only be triggered when using a lot of electricity (ie microwave, space heater, several things at once), but now it seems to happen at random times. The tenant even gave me a scenario of when he woke up early one morning to use the bathroom and it happened as soon as he turned on the bathroom light. No one else was up and therefore minimal electricity was being used at the time.

I have had PGE come out to look at the problem and its not their end. They also told me that because its happening to the entire unit at the same time, it most likely is a problem somewhere from the main box outside to the box inside the unit and specifically the neutral line. When he took measurements from the individual breakers inside the unit and measurements would be as high as 160ish in some parts while 40ish in others. You can also see this in the ceiling lights (unusually bright in the kitchen and unusually dim in the bathroom). This problem has also damaged several appliances and things within the house (dvr recievers, dvd players, etc).

Any suggestions? The electrician located the neutral line in the junction box. No damage or charring and the connection was still tight. He looked in the main panel outside - minimal corrosion, still tight. He added some paste to maximize conductance and that was it. The breakers inside are fine. He even opened up most of the wall switches and outlets to investigate but found nothing. Any ideas? This is a problem that has kept me up for about a month. I'm afraid of it being a fire hazard too.

Many thanks,
Mike
 
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  #2  
Old 04-10-12, 09:51 AM
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Voltage swings like that are an indicator of a loose neutral. This can and will burn up appliances and electronics. Since this is affecting multiple items the problem is in the panel or upstream of the panel.
 
  #3  
Old 04-10-12, 10:33 AM
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Thanks for the quick reply. Yes, that is what the electrician and PGE tech said too but they couldn't seem to find anything. By panel, you mean the panel inside the house? Upstream, meaning anywhere from this panel inside the house to the individual lines in the wall (ie light switches and outlets)?

Any suggestions on where to go from here?
 
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Old 04-10-12, 11:12 AM
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Upstream, meaning anywhere from this panel inside the house to the individual lines in the wall (ie light switches and outlets)?
Upstream means ahead of the panel on PGE's side.
 
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Old 04-10-12, 12:02 PM
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When he took measurements from the individual breakers inside the unit and measurements would be as high as 160ish in some parts while 40ish in others.
Open or loose neutral(s). Those are dangerous. I would inspect the neutral bus in the panel in the unit carefully. Among other things, I would look for: loose screws, or over-torqued screws damaging the conductor. If the non-standard voltage is present on the load side of most or all of the breakers, or if you can test between each ungrounded bus and the neutral bus and you find it on both of those, then I would especially check for a loose or over-torqued condition where the neutral feeder is connected to the neutral bus. If it's not universally measurable, I would look for any cracks in the neutral bus.

Heck, I'd do that anyway while I had it open.

If only some of the breakers are showing non-standard voltage, then the problem may be downstream - behind a light switch or receptacle, or above a light fixture. Note which circuits are above 120V. Those should be the ones that are hunting for neutral; I'd start troubleshooting those first.
 
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Old 04-10-12, 06:12 PM
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The electrician located the neutral line in the junction box. No damage or charring and the connection was still tight. He looked in the main panel outside - minimal corrosion, still tight. He added some paste to maximize conductance and that was it.
Is this an aluminum feeder? Is the feeder 4 separate conductors in conduit or is it cable, such as SER cable? Is the apartment wired with aluminum wire? By the way, there is no paste on the market that can maximize conductance. If what the electrician applied is an antioxidant compound, it won't help and is too late if you already have a high resistance connection. Antioxidant compounds prevent oxidation, but they don't remove it. You most likely have a high resistance connection that can be found by loading up the service and scanning all connections with an infrared camera. Most electricians don't have this equipment, but some electrical contractors will provide this service.
 
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