Momentary Power Outages

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Old 04-24-14, 05:40 AM
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Momentary Power Outages

My wife usually gets nervous when we get a momentary power outage here, thinking the issue is on our end and not the poco. For instance, last night the power went out for a moment in the entire house and it was perfect weather outside.

Got me to thinking to what would cause a momentary outage like this on the customers side?

My thinking its not likely since both legs would have to have an issue at the main, socket or at the poco connection for it to be a customer issue. That if it was a customer issue your more likely to see one leg go down or just a circuit.

Any thoughts on this? Would like to reassure the wife (and myself now that I have been thinking about it!)
 

Last edited by cws05; 04-24-14 at 06:00 AM.
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Old 04-24-14, 05:46 AM
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Got me to thinking to what would cause a momentary outage like this on the customers side?
For an infrequent total power loss of both legs? Nothing I can think of in a typical home would cause this short of a major issue which would cause frequent outages and eventually total and permanent power loss.
 
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Old 04-24-14, 06:10 AM
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FWIW - it happens to us on a frequent basis, in fact that's the main reason I bought a UPS for my PC. When I lived in fla we often lost power for 30 minutes or more, here in tenn it usually only lasts a few seconds - guess which one I prefer
 
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Old 04-24-14, 06:34 AM
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Not an uncommon occurrence. Most people don't notice it or most appliances are not affected. Today's power hungry society is putting a strain on our antiquated infrastructure and the power companies will make adjustment with transmission of power. Or maybe there is a weak link in the system that might be going bad. That being said I would suggest you get surge suppressors for any appliance including any newer refrigerator, range, TV and computer.
 
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Old 04-24-14, 08:24 AM
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Windy conditions can also cause power outages. As tree branches fall and knockout power in certain areas...... other areas will blink when that happens.

I've never seen it so windy on a continuous basis before.
 
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Old 04-24-14, 09:05 AM
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What kind of failure on the customer side could cause both legs to flicker off and on like this?

I assume a failure like this on the customer side would be more likely on just one leg or one circuit.
 
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Old 04-24-14, 09:48 AM
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What kind of failure on the customer side could cause both legs to flicker off and on like this?
Loose connections at the service entrance, especially in the bonding for the grounding electrode conductor.
 
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Old 04-24-14, 10:02 AM
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GEC , please explain? I would assume I could disconnect the GEC from the water pipe and the ground rod and there would be no difference in how the system works.

You have perked my interest since we just had a new panel installed. Including running a GEC to water ground, never had that before.
 
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Old 04-24-14, 10:24 AM
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I would assume I could disconnect the GEC from the water pipe and the ground rod and there would be no difference in how the system works.
Not so. That would eliminate your low-impedance path to ground.

You have perked my interest since we just had a new panel installed. Including running a GEC to water ground, never had that before.
You mention bonding connector(s) to your cold water service pipe and a ground rod. You didn't mention branch circuit grounded conductors, branch circuit grounding conductors, or the incoming service grounded conductor (neutral).

Did you live in the home before the panel was replaced? If so, did this problem get better, worse or remain the same when the replacement was done. If you did the replacement as part of improving an existing home that you'd just bought, can you ask the previous owner about their experience?
 
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Old 04-24-14, 02:04 PM
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I would assume I could disconnect the GEC from the water pipe and the ground rod and there would be no difference in how the system works.


Not so. That would eliminate your low-impedance path to ground.
I think we are getting off topic but im confused, I don't see how lack of grounding can interrupt power?

I understand how the two legs would be effected if I lost the service grounded/neutral but I was thinking in that scenario it would be seen as 0 voltage on one leg and 240 on the other or some inbalance in between. Not a complete loss of power and then return to normal as we see in a momentary power outage.
 
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Old 04-24-14, 02:14 PM
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What he meant was that it would have no effect on your issue, but would remove one of the safety features designed into your electrical system.

IIRC, if you lost the service neutral, you would probably indeed see dimming (low voltage) on one leg and blown bulbs(over voltage) on the other unless loads are perfectly balanced. Not positive, no Pro, but I did stay at a Do It Yourself Inn last night...lol.
 
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Old 04-24-14, 03:06 PM
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There is nothing at your end that could cause simultaneous full blackout and then simultaneous full restore of both legs like that. If it was a bad neutral, you'd see the symptoms that Vic just mentioned. It's entirely possible that the power company is simply unreliable. Our power has gone out on cloudless days before.. On more than one occasion it was for several hours. It could be an accident knocked down a pole, or a bird nest in a substation that caught fire (that one really happened here ). But momentary flicks are not uncommon in any power system. There's many reasons it could be happening, and all of them are the power company's fault.

Don't sweat it. There is virtually no chance of it being from some hazardous condition at your end. Have you talked to your neighbors to confirm it's happening to them too? I'm sure they could reassure her..

Edit: I just had an idea.. Do you have a smart meter by chance? If it does turn out that your neighbors are not affected, smart meters have a remote-control disconnect that the power company can use to cut you off if you don't pay your bill - and it could be acting up or receiving a rogue signal.. Just a thought...
 
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Old 04-26-14, 09:20 AM
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Thanks for your replies. Still waiting for clear explanation though where nashkat said:



What kind of failure on the customer side could cause both legs to flicker off and on like this?
Loose connections at the service entrance, especially in the bonding for the grounding electrode conductor.

What does the GEC have to do with momentary outages?
 
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Old 04-26-14, 09:53 AM
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In itself, nothing. But IF it is loose at a point where the neutral from the meter, neutral to the neutral bus and the GEC come together, then the 120v power wouldn't go unbalanced like you see with just the loose neutral, it would go out. Basically it cuts off all return path for the 120v power, so all that would work is straight 240v appliances like a water heater.

But again, the fact that it is cutting out and then back in instantaneously with absolutely no flickering, no apparent imbalance the other way (half your bulbs getting brighter), no buzzing, etc makes loose neutral/GEC connections anywhere a dubious notion.
 
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Old 04-26-14, 12:19 PM
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I think I understand better.

So essentially, if power was out to test for that scenario you would simply test an outlet to see if you have power hot to ground (but not hot to neutral)?
 
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Old 04-26-14, 01:08 PM
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You wouldn't have power in any 120v outlet in any configuration in that scenario. Seriously, the easiest way to find out is to ask your neighbors.
 
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Old 04-26-14, 01:21 PM
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You wouldn't have power in any 120v outlet in any configuration in that scenario.
You said the 240 would be present if the GEC and the neutral was jeopardized. That means you wouldn't have 120 hot to neutral but would have 120 hot to ground... 120 on either leg = the 240 you mentioned would be present?

So you could measure both sides of a dryer outlet in the scenario you present and get 240 but if you measure either hot prong to the neutral you would get 0 but you would get 120 from each hot to the ground slot??

Its all good, just continuing the discussion for the sake of understanding.. be kind, im far from a pro....
 
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Old 04-26-14, 01:55 PM
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Sorry I didn't explain it properly, I had another scenario in mind.. If everything is wired normally, yes. You will get 120v between any hot and a neutral, and also between any hot and a ground. The neutral and ground are connected together (bonded) at the Service Entrance (which is the first disconnect after the meter - it can be a breaker on the meter box itself, it can be a 'main disconnect' right under the meter, or it can be the first breaker box.

Now what I said was if somehow there was a fault where the neutral from the pole and GEC were separated from the house neutral and EGC (which again is an almost impossible scenario), then no 120v outlet would function because there would be no neutral return path to the pole transformer - either by the neutral or ground conductors. That's a lie unless everything was off

What would happen in reality is the devices connected to one leg would try to 'backfeed' to the other leg through devices that are powered on and connected via the common neutral. This backfeeding will cause the voltages to become visibly imbalanced: ie, half your light bulbs will become ultra bright and possibly burn out, while the other half will dim out. So if this were the case, on one leg you might see 200v hot to neutral/ground while the other leg will show 40v hot to neutral/ground.

Bottom line is you didn't mention any of this behavior, nor did you mention having to replace fried sensitive electronics like TV's or computers, so it's still realistically not something that's causing your problem.
 
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