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dick white
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join:2000-03-24
Springfield, VA

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[Electrical] Flickering lights

A question for the sparkies...

Christmas dinner at MIL house, as the evening wears on, notice lighting in dining room and else periodically going dim and then brighter. I've seen that in older houses with inadequate wiring as appliances turn on and off, but this was different. When an appliance (microwave, disposal, dishwasher) turned on, the lights would go bright, and then darken again when the appliance turned off. Exactly the opposite of what I would have expected. MIL and other family members say this has been happening for a long time, but seems to be getting worse. Reportedly, an electrician looked at things a few years ago and declared the problem to be outside power issue. POCO investigated and declared the problem inside the house. As noted, said to be getting worse.

Soooo, where would you suggest I begin looking? (Have not actually looked at anything yet, don't even know where the panel is in this house, but will be going back tomorrow and again in a few days, so thought I'd bring some meters and stuff to see if anything obvious is going on.) The lights getting brighter as the load increases has me scratching my head.

Thanks and cheers of the holiday to all
dw

garys_2k
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join:2004-05-07
Farmington, MI

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Could be a bad neutral connection to the utility. If it is it can be a BIG problem. Definitely monitor the light's voltage while running the appliances and see if they exceed the line voltage measured at the panel (the two 120 volt legs) under any circumstances.
LittleBill
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i would tighten the main netural line in the panel like gary said

Tursiops_G
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This problem also can be at the splice where the drop connects to the house (at the 'Weather-head')... If the connection checks out OK at the panel, then call the POCO to come out and check Their connections from the drop to the meter pan.

nunya
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Sounds like a dirty open on the neutral. This is usually outside (not always).
A word of caution, a dirty or open neutral can behave like a hot conductor and shock / electrocute in the right circumstances. It's not a good idea to get grabby or stick wrenches anywhere until you can verify N-G reading.
You should be looking for the following: A good cold water bond to the water line (if it is a metallic water line). A good ground rod outside at the meter. If it's older than 20 years, it probably needs to be replaced. A ground rod itself will not solve an open drop neutral, but help mitigate some of the damage / danger.

On more than one occasion, I've had to "do battle" with the power company on dirty open neutrals. Ask them to load test the drop. They have a machine available known as a "line buster" (or other trade names). It usually hooks right up to the meter socket. Essentially, it's two 120V heaters with corresponding voltmeters. If the guy doesn't have one on his truck, ask him to send somebody back who does. Not every troubleman carries them.
I've had open neutral sagas play out for months until the utility finally dug on them.

Open neutrals can (and do) occur inside - You can visually inspect the interior or the panel. Look for any signs of arcing / burning at the neutral connection(s), including the main lug.
Usually an open neutral on a branch circuit only affects 1-2 circuits (2 if it's a MWBC).

Regardless, it's not something you want to let go any longer. It needs to be addressed by a professional ASAP.
Speedy Petey
join:2008-01-19

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said by LittleBill:

i would tighten the main netural line in the panel like gary said

I WOULD NOT touch anything.

The chances that this is simply a loose lug in the panel is extremely slim. And telling him to tighten the neutral, when both unfused hots are about an inch away is truly unsafe advice IMO, for someone who we have absolutely no idea of their level of experience.

Call a professional as Nunya says.
IMO this is the only SAFE option.

jrs8084
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Statesville, NC

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I dealt with a dirty neutral a few years back. I was hesitant to contact the poco as I didn't know if they would take me seriously. At the advice of a few people here, I did call and kept my complaint simple (i.e. I didn't diagnose the problem) "My lights are flickering. Sometimes when I turn electric things on, the lights dim, other times lights get brighter" They immediately rolled a truck which surprised me. (New service drop and no flickering.)

Christmas Eve I was over at my friend's new home (new to him) and all his lights were flickering in the same way. When I pointed it out, some neighbors started saying how they see the same and thought it was normal and how they have learned to live with reseting clocks all the time.

ronaldmarion
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sorry for my ignorance but i never heard the word pocco before? can you elabourate?
n4bkn
join:2003-12-11
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POwer COmpany, or it might be the abbreviation of a specific distributer's name in Allandale,VA of the OP. (original poster)
aguen
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said by ronaldmarion :

sorry for my ignorance but i never heard the word pocco before? can you elabourate?

You folks UP NORTH tend to call it the Hydro, which evokes a similar level level of consternation/confusion down here.

mackey
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said by n4bkn:

POwer COmpany, or it might be the abbreviation of a specific distributer's name in Allandale,VA of the OP. (original poster)

It's POwer COmpany. In VA it would of been VEPCO or PEPCO before it got turned into Dominion a number of years ago.

/M

nunya
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In ironic fashion, my 1st service call today: open neutral.
This one was caused by a backhoe though.
walta
join:2001-05-22
Saint Louis, MO

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This could be very dangerous problem that should be checked by a licensed electrician.
My wild guess is that this home is wired with aluminum wires and you have bad connections.
This is very dangerous as a fire is likely.
As others had said an open neutral could display this symptom.
An open neutral wire could damage your electronics as when you see a dim light other circuits now are getting a higher voltage. If the ground wire is also damaged someone could easily be electrocuted.
If the problem were the neutral it is more likely the complaint would be this light is too bright and burns out often.

Walta
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I had the same symptoms about a month or so ago; some circuits would say to around 110v when a load was applied while other circuits would concurrently go up to about 130v. The power company came out and found that one of the feeder cables inside the panel was loose and arcing.

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I had a similar issues, and thinking maybe it was a problem outside called, Ga Pwr. Guy in a bucket truck showed up within a few hours and found that the lugs in the meter base were not making good contact with the meter and where burnt/charred, so he kept the meter and pulled the fuse at the transformer until we got the meter base fixed or replaced, we had replaced a little later that day, they came back once it was done and re-installed the meter and fuse.

Jack in VA
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join:2014-07-07
North, VA

Jack in VA

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said by Napsterbater:

I had a similar issues, and thinking maybe it was a problem outside called, Ga Pwr. Guy in a bucket truck showed up within a few hours and found that the lugs in the meter base were not making good contact with the meter and where burnt/charred, so he kept the meter and pulled the fuse at the transformer until we got the meter base fixed or replaced, we had replaced a little later that day, they came back once it was done and re-installed the meter and fuse.

Thank goodness here Dominion Power would have replaced it and the meter saving a lot of money and downtime on electric service. It's services like this that make a POCO outstanding.

Cho Baka
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Jack, really?

Jack in VA
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Jack in VA

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Yes really. Don't be bitter if you get ripped off.
LittleBill
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in PA POCO is only responsible for the meter itself, and the overhead lines. nothing else.
Mr Matt
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said by dick white:

Soooo, where would you suggest I begin looking?

A floating Neutral is nothing to trifle with it can lead to electrocution if the neutral is open or there is a high resistance between distribution transformer neutral terminal and the meter socket neutral terminal and here is why. When the neutral is open a voltage will develop between earth (damp concrete floor for example) and the protective ground unless the load on each hot conductor is equal or the resistance to the ground rod or earth ground bond is extremely low. In the case where the Neutral fault is between the meter socket and distribution transformer, the differential voltage will appear on both the neutral and protective ground conductors because the protective ground and neutral are bonded at the neutral terminal at the meter socket. The differential voltage will appear on any metal surface the protective ground conductor is connected to like a refrigerator. When an open neutral condition is reported to the power company a technician is normally dispatched post haste.
InvalidError
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said by dick white:

Soooo, where would you suggest I begin looking?

If it were me, I would get a pair of my multimeters and measure AC Volts from live to neutral on both halves of the split to confirm if this is a floating neutral issue (significantly dissimilar voltage between the two taps - in my previous apartment, I would sometimes read 105V on one phase and 130V on the other) straight from the power company.
Mango
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Mango

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What is considered an appropriate voltage fluctuation?

garys_2k
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said by InvalidError:

If it were me, I would get a pair of my multimeters and measure AC Volts from live to neutral on both halves of the split to confirm if this is a floating neutral issue

Sure, different loads at the transformer can cause differences in line voltage, but the OP's situation fluctuated as the appliances switched on and off. Having some lights brighten when the loads increase is a definite warning sign that somewhere in or near the house the neutral has too high an impedance.

Killa200
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said by Mango:

What is considered an appropriate voltage fluctuation?

Its less about fluctuation and more about distribution. If the neutral is dirty or open, you'll see both side of the split on the transformer be dissimilar in reference to the center tap, with the proportion varying depending on the load on one side of the other of the split.

On a normal service you might see 250v L1-L2 with something within a couple of volts of 125V L1-N and 125V L2-N.

A dirty or open, as an example, with a heavy load on one side might show 250V L1 - L2, but 95V L1 -N and 155V L2-N.

Grumpy4
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A little off topic

Old house = check the ground rod. Our office was in a 1700s house. Whenever lightning would be near, we would lose an electronic device. Turns out the ground system had corroded. A new properly installed ground seemed* to alleviate subsequent electronics losses.

*I say "seemed to" for I am not an electrician, and can't say for sure the new ground was the answer, but the point of my post is to suggest those in older dwellings take a look at their ground. Just sayin'
dick white
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Springfield, VA

dick white

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Thanks for all the good information. Update - the situation is more complicated than I first thought. House is 1966, so may or may not be aluminum. Underground service from a pedestal in the front yard. There is a subpanel as well. Pulled the cover of the main panel, did not see any evidence of arcing or burns. Didn't pull the subpanel cover, dinner was announced as served. Would have to spend some time documenting which circuits are on one phase or the other to see what was going up as the other went down. But the good news is that BIL (who lives closer) now has some information to work with when calling the family electrician and/or PEPCO. Thanks again.

Boooost
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said by dick white:

Would have to spend some time documenting which circuits are on one phase or the other to see what was going up as the other went down.

If they have an electric dryer, just measure the voltages on the dryer plug.

printscreen
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Will an open neutral cause a voltage to be present in the neutral line of outlets? Is that something I can test with a multimeter between the neutral of an outlet and a grounded appliance?

nunya
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It depends on the location of the open neutral. If it's before the main bonding jumper, no.
If it's after, then yes.

garys_2k
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Do you have a 240 volt dryer or other outlet? Check if the voltage between each hot and the neutral are more than a few volts different. 122 on one and 119 on the other, for example, is fine. Too large a difference can indicate a problem.