Lights dimming and flickering at night


Old 09-04-00, 06:31 PM
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My lights constantly dim at night and my bonus room lights flicker when I run my laser printer.

Here is a test I performed today on Labor Day. This morning (9:00 AM) I tested the 240 when I didn't get a flicker using my printer and then I tested it again around 9:00 PM when I was geting the flicker. Here are the results in voltage

Reading 1 with with all breakers off, Reading 2 with both AC's, stove, and dryer running.

Time Reading1 Reading2

9:00 AM 242v 235v
9:00 PM 247v 241v

Why does the voltage increase at night when more people are using electricity and more AC's are running. I would have thought a decrease. The PM time is also when I get the flicker. I also notice the dimming of the lights more.

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Old 09-05-00, 05:56 PM
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hello lyne,
frist off the flickering and dimming is more then likley due to high power comsumption on the transformer u r connected to, or a loose connection, on the powercompanys side.
the reasion the voltage was higher is due to the power company increasing voltage in an attempt to meet the high demand.
Old 09-05-00, 09:53 PM
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In my opinion the communities demand on the power company is usually less at night than during the day. During the day the factories are at full load capacity, and tend to go to skeleton crews late at night. They are your largest electricity damand factor. In the heat of the day the A/C units, both residential and industrial, are running full capacity and during the night less damand is required because the night cools off.
The voltages that you show does not show a problem in voltage. Your voltages that you reported seem to be fairly strong in both tests. You may have a bounce of electricity because of motors or other loads you have in the house or on the same line of the power company.
A nearby factory running a 150 horse power motor without a soft start that is starting and stopping could affect the flickering that you seem to be experiencing.
It may be that your service is too small for your dwelling demand load.
It may be a large load on certain branch circuits within your dwelling.
Many reasons could be the cause of your flickering. You might ask your Utility company to set up a voltage graph on your main feeders for a 36 hour period when you most likely expect the flickering. Then ask them to put their graph on your branch circuit that you are experiencing the flickering for the same period of time. This should help you locate the center of the problem.
If your flickering is located through-out your dwelling then problem will have to be the main service [upgrade your service size] or the Utility company [ask the Utility what they can do].
Utility companies claim voltage to be in tolerance levels between 205 volts and 245 volts phase to phase and 105 volts to 130 volts phase to ground. This range is more than I like to accept but the Utility Company is not controlled by us. They are controlled by the Utility Regulatory Commission.
If it is a branch circuit that is starving for voltage then start eliminating motors or other large loads that are found on that branch circuit. If you find a large load on that branch circuit causing the flickering then run a dedicated circuit to that large load and get it off of the problem branch circuit. This should solve your problem.

Good Luck tough problem !

Old 09-07-00, 11:26 AM
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What size is your service (Main breaker in your load center)? All 240v service is is two 120 volt feeds. They should be relatively equal most of the time. Test again, but this time place the black meter probe on ground and test one leg at a time with the red probe. This should give readings of approximately 115 volts. If one side is significantly lower than the other with your appliances turned on then you have an imbalance. If you're taking voltage readings I assume you have your face panel off - are there more wires on one side of the box than the other? Are there more 2-pole breakers on one side? An unbalanced load could make lighting on the heavier-laden leg flicker while lighting on the other side does not. Have someone move a few circuits to the other side and test it again if this is the case. I have also found a peculiar little problem which is much simpler to diagnose and to fix. I've found a weak connection in one receptacle which causes lighting on the same circuit to flicker. To find the one that's causing it I kill the breaker to the light that flickers, test which receptacles go off to find out which ones share that circuit, then turn the breaker back on and perform a simple test - I go to each receptacle on that circuit and jam a skinny screwdriver into ONE AND ONLY ONE slot and wiggle firmly. The one with a loose connection will cause the lights to flicker, and should be replaced. The culprit is usually that instead of using the screws on the sides, the installer used the "stab" connectors in the back. Over time the connection surfaces have become pitted. Otherwise, what wb said about telling the utility company is a good idea. I have found my local utility to be prompt and willing, although not always conclusive. They'll come to your house for nothing and look into it. If they can't figure it out they will probably feed you a load of crap and hope you'll swallow it and not call anymore. Then if the problem continues you keep calling. But if they seem to be able to give you an intelligent reason they'll either fix it or tell you that it's on your side of the fence and you'll have to hire an electrician.

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