flickering lights

[sparky1118]

Happy New Year everyone! I have an issue at my house that I haven't been able to solve and I was curious if any of you had any thoughts. I've lived in my house about 5 years now and my lights have always flickered and I cannot figure out why. They do it with every type of light bulb I install. I've installed two new ground rods outside figuring it was a grounding issue. I've redone from the service drop to the panel. I called Eversource (utility company) and told them the issue and they installed a new drop. But nothing is helping with the problem. Then grounds and neutrals are all tight and look fine. I've changed all the devices in my house and I still can't fix the issue. No one else around me is having the same issue. :?

 

[JFletcher]

One circuit, multiple, all? If more than one circuit, do the multiple circuits flicker all at once? They flicker, correct, not dim and brighten? Do all the lights on a circuit flicker, or just a few? Same ones each time?

eta: judging from what has been done so far, I would check for a loose ungrounded feeder wire or arcing/loose main breaker, if more than one circuit is affected. If it's one set of lights, check for loose breaker conection to bus, loose wire in the breaker, j-box or outlet box splice failing. W/o more precise info of the problem I can only wag.

 

[ptonsparky]

How far away is the POCO transformer? What size wire comes to your house? Overheard or underground? How many homes are feed from the same xfmr? Are they significantly closer to it? Ref JF post: Some dim as others get brighter?

My help looked at one yesterday that is about a half block of maybe #2 ACSR resulting in 117v L-N at the SE. Low for normal in this area. The portable electric space heater he found cycling would drop it another 4 on its branch circuit.

Some of us grew up using a set of test lamps for service calls but a couple meters would help here.

 

[JFletcher]

How far away is the POCO transformer? What size wire comes to your house? Overheard or underground? How many homes are feed from the same xfmr? Are they significantly closer to it? Ref JF post: Some dim as others get brighter?

My help looked at one yesterday that is about a half block of maybe #2 ACSR resulting in 117v L-N at the SE. Low for normal in this area. The portable electric space heater he found cycling would drop it another 4 on its branch circuit.

Some of us grew up using a set of test lamps for service calls but a couple meters would help here.

Important that the OP distinguish/verify that the lights are flickering vs dimming. My post leans toward problems with the former, yours the latter. Flickering ime (in my experience) is almost always a short/loose connection whereas dimming is a poco or load problem, with dim/brighten of lights at the same time a failing/gone service neutral.

 

[JFletcher]

Meant to address this in my first post:

They do it with every type of light bulb I install.

Small voltage changes affect incandescent lumen output much more than with CFL or LED. It's unlikely that a small voltage change (from say 120V to 105V) would even affect the latter two types.

I've installed two new ground rods outside figuring it was a grounding issue.

The grounding conductor and pathway are only used under fault conditions. Regardless of if the lights flicker or dim/brighten, a 0.000001 ohm pathway to ground (more properly, back to the source) will have the same effect as a 500 ohm pathway or no pathway: none.

I've redone from the service drop to the panel. I called Eversource (utility company) and told them the issue and they installed a new drop. But nothing is helping with the problem. Then grounds and neutrals are all tight and look fine. I've changed all the devices in my house and I still can't fix the issue. No one else around me is having the same issue. :?

If your lights are dimming for a few seconds, then returning to normal brightness, and there are no other apparent electrical problems, then it's probably due to a high(er) amperage motor load starting inrush current, like an HVAC unit, or even a dryer. Washing machine motors under agitation can produce faint flickering/dimming. See Tom's post #3 (excellent troubleshooting list) for other causes.

If they flicker, which is what I'd describe as a much more rapid event of varying intensity, then I'd start looking thru the things I listed in post #2. See if there are any seemingly unrelated events which coincide with the flicker.

In one case, I found shutting an interior door caused a bedroom light to flicker. I banged on the wall next to the switch mounted by the door, and was able to reproduce the flicker. I removed the coverplate and switch and the neutral had popped out of the backstabbed connection. The wires were also barely twisted under a wirenut. I re-made all the connections in the box (which were all loose).

In another case, I found a can light with loose connections. The kids jumping around on the 2nd floor produced enough vibration to cause the connection to momentarily make/break, causing a flicker. In still another can light, I found the center prong of a medium/Edison base lamp was barely making contact with the bulb, causing flickering.

Where you start troubleshooting will depend on where the flicker is, and how many lights/circuits are affected.

 

[Cub57]

I had a service call where the lights were flickering and I found a hair line break in the neutral bar


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[sparky1118]

Thank you for the responses everyone. All the lights in the house flicker not dim. Lights that are not on dimmers and lights on dimmers do it. LED, incandescent, and halogen. Everything in the panel is tight

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[Sahib]

Thank you for the responses everyone. All the lights in the house flicker not dim. Lights that are not on dimmers and lights on dimmers do it. LED, incandescent, and halogen. Everything in the panel is tight

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I suspect you don't have a neutral. To confirm, switch on a known load and check current through neutral on the service side with a clamp ammeter.

 

[ptonsparky]

Thank you for the responses everyone. All the lights in the house flicker not dim. Lights that are not on dimmers and lights on dimmers do it. LED, incandescent, and halogen. Everything in the panel is tight

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Turn off all the breakers in the House and add Incandescent Lamp loads to a temp CB on each leg. Use the same wattage lamp on each leg. Turn only those CBs on. Is the flicker still there? Yes? The problem is from that point out to the POCO supply. Only one lamp flickering? The problem is on that Leg.

Have you ever taken voltage readings?

 

[ptonsparky]

I suspect you don't have a neutral. To confirm, switch on a known load and check current through neutral on the service side with a clamp ammeter.

No neutral would be indicated by some lamps brightening while others dim and typically at 5 years some electronics would have fried by now. Not always, but most likely.

Note: Common metallic water supply with neighbors may change things.

 

[gar]

180103-0904 EST

sparky1118:

All good suggestions above. I started this before some of the newest comments came in.

Since you imply that many different circuits show flicker I would start tests at the main panel. Also clarify whether you are really describing flicker as defined by othetrs, or it is a longer duration drop.

How often this flicker occurs will determine how ro approach the troubleshooting.

To determine if the problem is before your main panel or interior to your home you wnat to make measurements directly on the wires entering your main panel. This really means get to the wire itself, not just the terminal.

But first, I will assume you have a digital meter with min-max capability. My Fluke 27 and 87 both have this capability, but the 87 is probably more useful.

Pick a light circuit where you see light flicker. Connect your meter to this circuit and monitor thru a time peroid where flicker occurs. Record the min and max values, and the average if available. This will serve as a reference for other measurements.

Next measure at the main panel the min and max line to line (240 V) voltage. If this shows large variations, then the problem is on the power company side of your main panel.

Now suppose little variation occurs in the 240 line to line. Then do a separate measurement on each line to neutral on the wires into the main panel. If a large variation occurs, then there is an incoming neutral problem. Since there was no 240 problem it means the neutral problem is within the transformer, at the transformer, or in the neutral path to your main panel.

If things look good into the main panel, then do the same tests on the panel bus bars. If these are good, then look at outputs from the main panel at the main panel.

Since you have indicated all lights in the home are affected, this seems to infdicate a problem within or before the main panel.

A useful neutral test uses two small bulbs, like 15 to 25 W to reduce brightness to your eyes, connected between the two hots and neutral in various ways, and points.

From your most recent comments it appears that the problem is within your main panel or somewhere before the panel working back toward the power company. Take particular note of whether the 240 into your main panel is stable or not. If stable, then the problem does not occur on the transformer primary side.

.

 

[Sahib]

No neutral would be indicated by some lamps brightening while others dim and typically at 5 years some electronics would have fried by now. Not always, but most likely.

Note: Common metallic water supply with neighbors may change things.

Lights flickering would also be there if there is intermittent arcing/current in the service neutral. Let OP check anyway.

 

[mbrooke]

Is the flickering continuous or 2-3 second spells? What time of day does it take place?


Your story reminds me of something similar. Turned out the POCO transformer was sharing a detntist's office/doctors office. Every time they did an X-ray all the loads connected loads would flicker for a few seconds.

 

[readydave8]

Lights flickering would also be there if there is intermittent arcing/current in the service neutral. Let OP check anyway.

Just the neutral? Or would intermittent arcing/current on service hot do same?

(neutral=grounded conductor; hot=ungrounded conductor)

 

[Sahib]

Just the neutral? Or would intermittent arcing/current on service hot do same?

(neutral=grounded conductor; hot=ungrounded conductor)

Yes you are correct. My suspicion is neutral is lost in OP case and circuit is closed through other intermittent path back to source. A check on service neutral may reveal it: no current flowing through it.

 

[sameguy]

Is this a pre built delivered home?
If so you could have many connections not tight.

 

[11bgrunt]

Happy New Year everyone! I have an issue at my house that I haven't been able to solve and I was curious if any of you had any thoughts. I've lived in my house about 5 years now and my lights have always flickered and I cannot figure out why. They do it with every type of light bulb I install. I've installed two new ground rods outside figuring it was a grounding issue. I've redone from the service drop to the panel. I called Eversource (utility company) and told them the issue and they installed a new drop. But nothing is helping with the problem. Then grounds and neutrals are all tight and look fine. I've changed all the devices in my house and I still can't fix the issue. No one else around me is having the same issue. :?

The POCO only needs to meet the 3% VD standard and you would have to prove they haven't if that is the real problem. They own recorders and should be able to determine if this a voltage drop issue up to your meter.
If it is lights dimming and you have had this problem for five years, it is probably voltage drop oriented and the only fix is reduce the voltage drop. To remove the symptoms, I am recommending that non dimming LED bulbs be used. I have tested many bulbs over many years to determine which type displayed the least amount of dimming. A non dimming LED can experience voltage changes in excess of 10% with no effect on what you see when looking at the bulb.
As stated before, flicker and dimming are two different things. This link discusses flicker.
https://www.powerstandards.com/tutorials/what-is-flicker/
The utility has a standard they must meet for flicker. When I look at these complaints, I use a meter that can record flicker. I have been involved in cases where large industrial customers did affect the POCO power quality to residential customers and that was reported as lights flickering.
The idea that no one else is having the same issue may be a red herring. If you have the right bulb and the right color of paint on the wall to reflect the flicker and you are hyper sensitive to the flickering, it could be at your neighbors and they are not aware.

 

[meternerd]

I agree with those who say the POCO should set up a recorder to monitor voltage over a period of at least 24 hours and they should give the customer a copy of the results. The customer may not understand what they are seeing, but it's good for customer relations for the POCO to try and solve customer complaints. It's not always possible to convince the customer that the problem is on "their side" but at least they know you are trying to help solve the problem.

 

[gar]

180103-2126 EST

A quick experiment with my Fluke 27.

At an outlet location away from the main panel over a minute period read a max-min variation of 0.1 volt.

Loading the outlet with a 100 W incandescent produced a difference of 0.4 V. Note that the bulb is 10 ohms at turn on dropping to about 144 ohms within a cycle. But turn on was at an unknown point in the AC voltage waveform.

With a 1.5 V change in incandescent bulb voltage at a nominal of 120 V I can slightly detect a flicker (change in light intensity).

I suspect the flicker of the original post is much greater than from just a 1.5 V change. I will guess 5 V or more. Relative to my general voltage variation I believe studying the present problem could be done easily with a Fluke 27 min-max function. Min-max should be reset often enough that it is primarily providing information on the flicker voltage.

See photo P27 at my website http://beta-a2.com/EE-photos.html over a 4 hour period. The voltage is averaged for 1 second periods and the graph has resolution to 1 second. Voltage resolution is 0.1 V from a TED 1000 monitor. The voltage is not always this stable. P26 is a 24 hour period, resolution is still 1 second.

P22 thru P25 are before I had better graphing, but show a time period where input line voltage variations in steps occurred unsynchronized with my load changes. Some big load somewhere on the power system, or a voltage regulator problem.

P29 is voltage at the outlet to which a freezer was connected and shows the voltage variation correlated with the load change.

.

 

[junkhound]

Happy New Year everyone! I have an issue at my house that I haven't been able to solve and I was curious if any of you had any thoughts. I've lived in my house about 5 years now and my lights have always flickered and I cannot figure out why. They do it with every type of light bulb I install. I've installed two new ground rods outside figuring it was a grounding issue. I've redone from the service drop to the panel. I called Eversource (utility company) and told them the issue and they installed a new drop. But nothing is helping with the problem. Then grounds and neutrals are all tight and look fine. I've changed all the devices in my house and I still can't fix the issue. No one else around me is having the same issue. :?

a. Do you have an induction cooktop, or run your microwave oven at less than full power setting? Those appliances control lower power simply by switching on and off at a 1 Hz or so rate. Even some non-induction electric cooktops cycle power on and off for power settings vs. the old method of just changing the element connections.

b If the flicker is longer than 1 second cycling rate, even coffee pots can cause flicker.

c any positive displacement pumps? A large compressor load (5T reciprocating compressor heat pump or 5 HP shop air compressor) can easily cause flicker due to current draw peaks at top of compression stroke, more common for shop compressor.

LED or fluorescent should not flicker due to voltage variations IF they have a high quality electronic ballast, magnetic ballasts will flicker.