electrical interruption

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It's a gusty day. I was in a house across the street when a light flickered for two seconds. Digital equipment in three rooms had to be reset: microwave, answering machine, computer, and television.
I've always assumed such flickering comes from arcing in a transmission line, but digital clocks in two other rooms were not affected. The same transformer supplies my house, and none of my digital equipment was affected.
What could cause power fluctuations that would affect household electronics on some circuits but not others?
Choreboy
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On Sat, 02 Apr 2005 20:22:50 -0500, Choreboy wrote:

Probably a bad ground in your breaker box. Look for discoloration.
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it is possible that one side of the 240 went out and not the other but noy likely
most probably the outage was long enough to reset some but not all
Mark
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The clocks probably have battery back-up so that the alarm will not be reset if the outage comes when you are sleeping.
Some other equipment had large enough storage capacity for the power supply so that it will survive a brief outage without resetting.
Charlie

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Many electronic devices will have filter capacitors in the power supply and so it will take some amount of time for the dc buss voltage to drop when input power source is disconnected.
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Choreboy wrote:

Probably the difference in the electronics. I have one VCR that always require a reset with an interruption and another VCR that isn't usually bothered. Same applies to some other electronics.
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That house may have a loose feed it is something your utility will check and fix free even on sunday as it can damage electronics. I had that problem. The clocks probably have battery backup.
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Choreboy wrote:

The problem might be local to that house, such as a bad connection in the service drop. Also, some electronic equipment will withstand a brief interruption in power better than other equipment.
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Choreboy wrote:

I suggest that you may want to invest into some whole house surge protectors in addition to any point source protection you now have or may add. That kind of problem can be an indication of possible surge problems. Most newer equipment is less sensitive to surge issues and they also are better able to maintain a few seconds of outage and still maintain their internal memory. I suspect what you found was that some of your equipment is older or of low quality than those that maintained their time.
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m Ransley wrote:

The flickering of the ceiling light lasted long enough for the lady of the house to ask, "What's that?" and me to turn around and see it.
After finding four electronic devices scrambled in three rooms, she checked the bedroom clocks, saying they always go out if the power flickers. They were fine. It makes sense that the breakers for the side of the house with the problems would be on the same side of the breaker box.
The same transformer supplies my house. I have computerized stuff plugged into both sides of the line, and none was affected. However, the line that supplies my neighbors supplies another neighbor, who says she had to reset her electronics after her lights flickered at the same time yesterday.
I guess it's a splice up above. I see a couple of popped splice covers up there; maybe they overheated sometime due to resistance in the connection. Could a bad splice have welded itself during the flickering? As it didn't affect my service I suppose I shouldn't be the one to report it. What would my neighbors risk by not reporting it?
Choreboy
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You are making assumptions rather than first providing facts. For example, how do you know breakers on one side of the breaker box would be on same phase? When a 240 volt breaker is installed, it provides both phases from same side of that box. Why does this make sense:

That is only speculation. It is responsible to ask why this strange failure occurred. But it leads to nothing useful when you assume.
What could have caused the problem? Let's see. I only have one idea. Therefore that *IS MOST LIKELY* the reason for your problem. Some others posted using this logic.
You have provided woefully insufficient information for anyone to post a probably reason. But even worse, your own posts are based in speculation. No wonder others posted using only speculation as a probable reason.
Every electronic appliance has a unique cutoff voltage. These are numbers so necessary to appreciate what happened. Intel even states how low voltage can go and computer still works just fine. Voltage so low that incandescent bulbs are at less than 40% intensity. Other appliances may cut out at higher voltages. Again, without that number or knowing which phase each connected to, then no useful facts are available. Tom MacIntyre once identified a 120 VAC TV that worked until voltage dropped below 37 volts. All other electronics could shutdown while the TV worked? What does that tell us about household wiring? Nothing.
Every appliance must also work so many seconds after power is lost - as both Mark and PrecisionMachinisT noted. Another number that varies depending on that appliance's internal design - and that was not provided. Just more reasons why what did and did not work provides nothing useful.
You don't have numbers. Your facts are mostly speculation. Don't speculate as other posters have done. To learn, at minimum, you must measure voltages between wall receptacles that did and did not lose voltage. If for no other reason to learn which phase each receptacle is connected to - without speculating.
Choreboy wrote:

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w_tom wrote:

That'a true. My neighbors don't have an instrument recording the voltage at each outlet.

Do you mean visible light or total radiation? Why not say what voltage you mean?

Here are facts. An interruption too brief to see even at night will knock out my phone clock, microwave clock, and computer. The problem at my neighbors' was conspicuous in daylight as the lights went on and off for several seconds. My house was fine. I'd say the problem did not affect the transformer output terminals.
Here's another fact. The reason my neighbor checked the bedrooms was that in her experience, any time she had to reset the stuff on one side she would also have to reset the bedroom clocks. She was amazed to find them working.

My TV seems more sensitive when it's off. An interruption too brief to stop my microwave clock will keep my TV from turning on later. I did not have to reset it yesterday.

Those appliances that work so many seconds without power could be useful. How many seconds must they work? Are they expensive?

As a matter of fact, I was about to go over there with a DMM and an extension cord this afternoon to check phases. Instead, I called a neighbor who lives on the other side of them. She told me that when my neighbors' lights flickered, so did hers. She had to restart her computer and reset digital clocks.
By the process of elimination, I think that in the 50-mph gusts that had been occuring that day, one of the splices feeding their houses got worked into a high-resistance condition for a few seconds. Have you a better explanation for the facts?
Choreboy
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Rightly proper to look into this anomaly before it becomes serious. If nothing else, fixing a problem before it happens can only be a good thing. Using that extension cord and meter does do one thing important. For example, proving all interrupted devices were on one phase, then empowers a utility crew to repeatedly check only one spot until they find something. If ailed devices are on both phases, then the utility crew is encouraged to on a neutral wire problem - a failure that may eventually get destructive if not found.
IOW by obtaining that one little additional fact, then a utility crew has better reason to play more aggressively (concentrate their attention) only on those live wires that can explain your 'unique' symptoms.
In specs for computers (for example), a 100% loaded computer must keep working when power is lost for 16 msec. All will typically keep working even longer. If voltage drops so low that incandescent lumens are less than 40%, then a computer must still work just fine. These are characteristics defined by specs for computers. Other devices such as digital clocks may not be so resilient. I said seconds. Not full seconds. Milliseconds. Every device will keep working a fixed period after power is completely lost. Some just work longer. Computers tend to be some of the more resilient to dropouts. Some clocks tend to withstand dropouts longer. Some clocks may have a battery or internal capacitor so that short interruptions don't bother them.
But again, determine if all 'interrupted' appliances are only on one phase or both. A utility crew would be more likely to aggressively shake the suspect live wire rather than uselessly checking all. That information also tends to make them more believe you do have an intermittent problem.
Choreboy wrote:

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Dan C wrote:

Hi, Some electronics device such as clock may have back up battery within, some has big storage cap. inside which will ride out momentary flicker. Tony
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Oh no, 240! The affected outlets represent both sides of the transformer! There goes my speculation of a loose splice on a secondary line. I don't know why so much in two houses had to be reset but everything at my house was fine.
(It's been years since I looked inside a breaker box. That's why at first it seemed natural to me that all the switches on one side would come from the same side of the 240-V supply.)
w_tom wrote:

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Maybe loose splice on neutral wire? But this would also cause some lamps to sometimes glow brighter and some incandescent bulbs to fail faster. Defective neutral is also just another human safety reason why the earthing ground rod is important attached to breaker box.
Symptoms are getting squishy. Once it appears contained, it squeezes out somewhere else.
Choreboy wrote:

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I can ask if they've noticed bulb problems. I've been over there many times in the evening and the lighting was steady.
I know a retired lineman who runs marathons. Today at the track I managed to keep up with him long enough to inquire. He said, "Whole-house surge protector."
He's right in that I have one and they don't. What I observed was rapid dimming of bulbs in a fixture as if it were repeatedly being switched off. I suppose spikes could have scrambled the TV, answering machine, and microwave, but the computer was plugged into a brand-name surge protector. Does his guess sound good?
I don't understand the benefits and limitations of the surge protector in my breaker box. It's a semiconductor clamping device that I installed about 1985. At New Years of 1999, ice brought down high-voltage lines a few miles away. In spite of my surge protector, my TV and stereo were damaged so badly that they weren't worth fixing. (A plug-in protector prevented damage to my computer, which was on.)
w_tom wrote:

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Brand name plug-in protector are promoted like Listerene and Geritol. There is no such thing as a quality plug-in protector. Take a $3 retail power strip. Add some $0.10 components. Sell it for $15 or $50 because myth brokers now call is 'quality'. Worse still, the adjacent protector can even complete a surge destructive path through the appliance. Just another little fact they forget to mention.
A 'whole house' protector connected 'less than 10 feet' to a single point ground is essential for every home. Every phrase in that sentence has critical importance. 'Whole house' protector is not required for human safety. Therefore no building code requires this effective protector. (Remember, the protector is not protection. Earth ground is the protection. But that discussion is irrelevant here).
Although a 'whole house' protector should be priority for every homeowner (especially with summer T-storm season approaching), still, that protector is not a solution to your flickering problem. You (and neighbor) suffered a voltage drop - a brownout or sag - so low that even electronic appliances were affected. Many different electric problems exist. A transient is a high voltage. A brownout is low voltage. A surge protector is only for high voltage transients that occur typically once every eight years. Protector would do nothing - completely ignore - a brownout or blackout.
Yes, the linemen properly informed you of something essential for every transistorized building. Absolutely essential. Something missing on most all buildings. Something so important to transistor safety that every lurker should be now planning trips to responsible stores such as Home Depot and Lowes. But surge protectors - the effective 'whole house' type or the scam plug-in type - will provide nothing for this brownout or blackout problem.
Among suspects should be inspection of the circuit box. For example, some Federal Pacific breaker boxes have been known to burn down the building. Flickering would be a symptom of future serious failure. The flickering may be nothing. Or it may be symptoms of a future and major problem. In previous posts I mentioned, in passing, the inspection of many things such as the earthing rod. Inspection of that circuit box (including feeling for heat on non-conductive surfaces) is another. Immediately cannot say if those inspections would or would not explain the strange flicker. But then even the military demands such inspections every five years or less.
Yes, even an intermittent neutral wire does not explain your symptoms. However this assumes just one problem. It might be a combination of intermittents that conspired to cause that flicker. Best we can do is inspect the usual suspects, and 'keep your ears on' for future symptoms. That strange flicker would bother me to no end - just like the near disaster of a Space Shuttle one full year before Challenger exploded for the same reason. The engineers never stopped asking why and therefore could have saved Challenger; if their management had minds of innovators instead of bean counter mentalities.
Best to do as you are doing and to inspect those various suspects previously recommended for inspection. Sorry I cannot offer up a likely suspect. Best I can do is add to the list of suspects and encourage you to keep being suspicious.
Choreboy wrote:

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w_tom wrote:

Outlet strips won't do much and are sometimes called surge protectors. With a surge protector, I guess you got MOVs or something else to dump surges, inductors to show high impedence to transients, and something to blow quickly if an MOV can't handle a surge.
With a whole-house protector, all you get is something to dump surges. If it opens, how do you know? If it shorts, your whole house is dark.
If I had to choose how to protect a computer, I'd choose a plug-in unit, but I've never understood whether a $50 unit is better than a $15 unit. As you say, the components are cheap.
I have heard that plug-in-units should be replaced every year or two because they deteriorate. I don't know if that's true. It seems to me that a well-designed unit can be trusted until the light comes on and you can't get power.
[...]

When ice brought down a high-voltage line a few miles away, my whole-house protector didn't save my TV or stereo. My scam plug-in protector saved my computer, external drive, and modem.

It was a gusty day, and the woman across the street from them had flickering at the same time, after which she had to restart her computer and reset clocks.
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The plug-in protector does nothing effective. A properly sized protector should not vaporize or opens when shunting typically destructive transients. If protector is vaporized, then it provided ineffective protection.
Often an adjacent TV may suffer no damage, but the protector fails catastrophically (catastrophic damage must never happen to a protector as defined by MOV manufacturer data sheets). Then the naive assume, "the protector sacrificed itself to protect my TV". Reality: protector was so grossly undersized as to fail while TV's internal protection protected the TV. Remember, a transient confronts TV and protector at same time with equal force. Protector does not sit between a transient and TV - as myths claim. Protector connects to AC mains just like another light bulb. But if the protector is undersized, then some humans will speculate, "the protector failed to save my TV". A transient too small to harm the TV instead destroyed a grossly undersized (and overpriced) protector. What kind of protection was that? Ineffective plug-in protector was damaged by a transient too small to even harm the TV.
What does that human do? Buy more grossly undersized and overpriced protectors - and recommend them to friends. A properly sized protector means no one knows a transient occurred.
We install properly sized protectors so that failure is not an issue. Protector is installed for events that occur typically once every eight years. But to sell more $3 power strips with some $0.10 components for $15 or $50, then I too would hype a myth that protectors must be replaced every year.
Protectors degrade quickly when undersized. But again, numbers expose the myth. Take a typical 345 joule plug-in protector. Maybe it will last for two equally sized transients. Therefore even the minimal 1000 joule 'whole house' protector would last for maybe 300 of those same sized transients. 2 verses 300. Protector installed for events that occur typically once every eight years. Damning numbers that reverse 100% your reasoning.
Increased joules causes an exponential increase in protector life expectancy. So why are plug-in protectors so grossly undersized? They are not providing effective protection. Why waste more money on more $0.10 parts to properly size a protector. If it fails, then the naive will hype "the protector sacrificed itself to protection my...."
How do you know the 'whole house' protector did not save appliances? Do you do as I do - identify the electrical path AND replace all electrical components? How do you know that plug-in protector did anything? What is the criteria? Again, the old Missouri adage. Show me. What are the facts? Which components did and did not fail? What was the complete circuit of that transient?
In another example, the VCR may have shorted to protect an adjacent TV. Then the naive human assumed a plug-in protector provided the protection. But he could not explain why the VCR was damaged. Turns out, the transient never saw the protector. But again, this level of detail so often demonstrates plug-in protectors as ineffective. How many joules in each protector? Why are some so grossly undersized as to be damaged? Just more damning numbers.
Then we have price. One spent $15 or $50 for ineffective protection of each appliance. The properly sized 'whole house' protector costs about $1 per appliance. Worries about the 'whole house' protector shorting, not indicating a failure, or leaving a house dark are not valid. Reasons why involve details made obvious when the 'whole house' protector is installed.
A protector that catastrophically fails (vaporizes) is classic of undersized protectors. But then where would you want such a protector? On a desk full of papers, or in dust balls on the rug behind a desk? Plug-in protectors are not just undersized. They are in the wrong location for human safety. Just more reasons why the plug-in protector is not effective. The most damning reason - no earth ground which means no effective protection.
Intermatic once provided a brochure describing an event in their sales manager's house when Andrew went through Florida. High voltage primary wire dropped on a wire into his house. Intermatic 'whole house' protector was badly burned. But it shunted the high voltage primary voltage until a utility fuse finally cut off those thousands of volts. Nothing inside his house was damaged. The house did not catch fire from thousands of volts on 120 volt appliances. Plug-in protectors did not vaporize while sitting on combustible materials inside rooms. Properly sized 'whole house' protectors for about $1 per protected appliance? Or $15 to $50 for the grossly undersized and ineffective plug-in protectors?
These are damning numbers. And then we add the most important fact. The protector is only as effective as its earth ground. Bottom line fact that plug-in protectors avoid discussing to sell at 15 or 50 times the price.
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