0

Background

  • My house has 100 amp service with all copper wiring and all wiring contains a hot, neutral and ground wire.

  • The past three weeks the lights in the house go dim and bright. The fridge makes a little noise when the voltage drops/spikes. It happens sporadically and some days it won't happen at all, other days it happens frequently throughout the day (no pattern to the time between occurrences).

  • The load doesn't seem to affect when this happens.

  • When the problem first appeared I started checking the voltage on the panel. When it happens one leg will drop down to around 118 volts for a few seconds, when it typically stays around 122 volts. One time one leg spiked to 169 volts.

  • As i'm writing this message the fluctuation in voltage has happened at least five times, no load change in the house has occurred over that timeframe.

What I have done

  • I had an electrician come check the panel and verify I have no loose neutrals. He said the power company is to blame. He checked out the panel and didn't find any issues. Unfortunately the spike / lowering of voltage didn't happen while he was here. I called power company.

Here is how my visits w/ power company has gone:

  • Visit #1: Technician comes out, checks voltage at meter. Monitors voltage for a few minutes, no problems arise then leaves. Declares no problems on their end.

I start watching the neighbors house to see if they are getting any power fluctuations. I notice it is happening for them also. I speak with the neighbor and they claim it has been happening for months to them. They thought it was wiring in their house. Unfortunately they are renters and they can't be counted on for any help.

  • Visit #2: Technician comes out, I'm home this time. He monitors voltage and has me put load on the system. Everything checks out, nothing happening. I tell him neighbors experiencing same issue. He says not seeing anything, will do a 'line trace' in a few days.

  • Visit #3: Three technicians come out they check voltage at my meter, let it run for awhile. they check neighbors meter, find neighbor has issue in the meter and they fix the issue. They still don't see anything happening at my meter.

They say the transformer is relatively new and say it can't be the problem. As they are walking around the poles and other houses, I look at the volt meter they have installed at my meter and it drops down to 118 volts. I mention this to technician and he says that shouldn't happen.

I ask one of the technicians if something was going out in my neighbor's house could that impact my voltage? I said they have been running their AC all the time. He said it should have a thermal overload and not cause any issues w/ other neighbor's electricity, but he has seen where things fail and it can cause issues.

Technician's leave saying these things can take time and need to be patient.

What to do next?

I'm far from an expert on this, so any help is appreciated. I don't want voltage fluctuations harming things in the house.

Could something in my house be going bad which is causing the issue? Should I start turning off circuits in the house and see if the problem occurs? Would that be one way to troubleshoot the issue?

I'm afraid the burden of proof is on me now regarding the power company.

2

120v is supplied as two "legs" of 240v. In a perfect world, loads would be balanced and neutral would not be required. Neutral is there to assure the midpoint stays the midpoint even if the two legs are not balanced (and they are almost always not balanced).

A couple of volts of drift is no big deal, and is a normal and healthy effect of uneven loading on the legs (you could reduce it by using extra thick wire, but then you're wasting money).

However, tens of volts of drift says the neutral is not doing its job, you have an open neutral or lost neutral. This means balance is a matter of luck, and most of the time some appliances will see less than 120V while others see more than 120V, which is likely to damage the appliance and even start a fire.

240V loads such as oven, water heater, installed A/C unit, electric-car charger, heat pump, installed electric heat or electric dryer, will have no effect whatsoever on a neutral problem.

The fact that neighbors are also having the problem helps. What would help the most is if you have some sort of data-logging system actually recording leg voltages over an extended length of time. Significant shifts in leg voltage (I don't mean 2 volts) would absolutely reveal a damaged or lost neutral.

  • I took footage of the voltage change. I compiled three different voltage changes in this video that happened around a five minute time span. The video has been edited so it is around 1:20 seconds long. Sorry for the shakiness at the beginning of the video :-). Taking w/ my phone. Here is the link - drive.google.com/open?id=0B8T5Z6Jz_9onZ3FkVWc4QUdCLTA Looks like around a 5 volt change is what is happening at times. You can see the lights dimming in the video. – RDotLee Apr 11 '17 at 2:35
  • The video is really only around 35 seconds long - I didn't trim it when I uploaded it. – RDotLee Apr 11 '17 at 3:01
  • So it rides at 122V then abruptly drops to 118V every 4 seconds or so. I would put the meter on the other pole and see if it does the reverse there. – Harper Apr 11 '17 at 16:36
  • I'll do that once it starts back up. – RDotLee Apr 12 '17 at 3:07
  • 5 volt swing is no big deal, if an industrial site is on the same line as your home even miles away when they start and stop large motors the line voltage will vary. Seeing 169v on a 120v outlet would scare the crap out of me you have had your neutral checked so it should not be the problem but while monitoring try turning on the electric range, dryer, or other 240v devices to verify everything inside the house is good with a load. If the voltages are stable with 240v loads being turned on and off it is a power company problem. Getting video of a wild reading like 169v will get there attention – Ed Beal Jan 25 '18 at 14:35

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.