Ugly back feed from neighbor during power outage?

[JoeWras]

We just had a power outage. (Aside: power company fixed it in one hour. Tree fell on lines.) Power went out, and 3 seconds later, odd things. My mind wasn't grasping what was happening for a few seconds, then I realized we had partial light, but oddly and dimly. One outdoor light, my weather station, and my desktop mini globe. Seeing 2 out of 4 overhead can lights on, my mind went to "single transformer leg failure!" and raced to the basement and flipped the whole house off.

But then I thought about it. Why would 2 out of 4 lights be on dim on a single circuit set of can lights, which I wired, so I know it is one circuit? Then it dawned on me that I was seeing very low power devices work only half way. We were getting very low power, and I'm guessing it was from some neighbor back feeding onto the grid. In the past few years, we've seen more solar installations, and also whole house generators. I'm guessing one of these has a wrongly wired transfer switch.

This is not good. I know "the internet" always talks about killing linemen from this. They aren't wrong, but I've also read that linemen see so much of this they account for it and add extra grounds and other precautions while working.

I think flipping off the whole house wasn't a bad idea. I see nothing good of having some weak feed come into the house. But I'm not sure it can cause damage. Can it? And has anyone ever seen this? This is an absolute first for us. I know single leg failures can do a number on equipment like A/C units. But I'm not so sure a weak feed with low amperage would do anything. Any thoughts or experiences?

 

[braumeister]

I would tell the power company about it so they can investigate.

 

[JoeWras]

I would tell the power company about it so they can investigate.

Good point! Will do, if I can make it past their phone robot.

 

[Flieger]

Definite incorrect hook up. Neighbor probably plugged generator in to a home circuit to run it back through his panel (probably doesn't have a transfer switch) and didn't turn off the main breaker to avoid power going out to the main line. This is a common mistake that as you said has bad outcome.

Flieger

 

[DayDreaming]

...I think flipping off the whole house wasn't a bad idea. I see nothing good of having some weak feed come into the house. But I'm not sure it can cause damage. Can it? And has anyone ever seen this? This is an absolute first for us. I know single leg failures can do a number on equipment like A/C units. But I'm not so sure a weak feed with low amperage would do anything. Any thoughts or experiences?

I had a recent outage where I was getting about 60 volts from my outlets. I know this because that's what my computer's UPS was showing me. I did unplug the fridge and turned off the power strip for my TV/home theater because it kept trying to turn on, then off, then on... Flipping the main breaker off is a smart thing to do, but I didn't because I wanted at least a few lights on. No damage was done when power went back to normal 6 hours later.

 

[street]

Sounds like back feed from neighbor's gen or back feed from service area around you. A 3=phase service or single-phase service could be coming back at and creating that dirty voltage.
You did the right thing hit the main OFF and report your happening to the owner company.
Working my whole life in the high voltage industry back feed is a very deadly thing for line workers and the public.

 

[Spock]

...I see nothing good of having some weak feed come into the house. But I'm not sure it can cause damage. Can it? ...

Today's appliances are made so cheaply that brown-outs, low voltage, etc. can cause a lot of damage.
And if the back feeding generator is a newer model, it's output is also quite dirty with high distortion and only approximating a sine wave at the source.

 

[JoeWras]

Today's appliances are made so cheaply that brown-outs, low voltage, etc. can cause a lot of damage.
And if the back feeding generator is a newer model, it's output is also quite dirty with high distortion and only approximating a sine wave at the source.

I have this silly levitating spinning mini-globe night light. That thing was doing some pretty weird pulsing that seemed a lot like a severely chopped 60Hz wave.

Nothing about this was clean.

I walked around and only heard one generator a few blocks away. There could be one closer I didn't hear. We do have a few solar panel arrays on homes, one only 4 homes away. They recently got a new roof and had to remove the panels, then replace them. They had the solar company do that, not the roofers. These are second owners of the home. The guy who installed them was a tech nerd. Not sure the new owners have it right. Then again, I'd assume these would disallow back feeding during an outage. The metering is pretty sophisticated and is supposed to stop just this kind of problem. The outage was at dawn so it would be batteries only on the solar homes.

 

[GrayHare]

As I understand it, at half normal voltage, anything with an electric motor is going to draw more current than designed for and potentially overheat.

 

[1242Vintage]

My guess is that it’s someone nearby who has small generator and has plugged it directly into a wall plug in order to energize a single circuit in their home.

 

[JoeWras]

My guess is that it’s someone nearby who has small generator and has plugged it directly into a wall plug in order to energize a single circuit in their home.

Maybe. But the dim lights presented within seconds of the failure.

 

[JoeWras]

OK, there has been damage. Either my security cameras got blown, or the POE router is blown. Further investigation is required.

I've also seen the AT&T fiber truck running around. Most all my electronics are on back up battery/surge protectors. But not that POE router for the cameras.

 

[Texas Proud]

This will be an interesting read... let us know what happens in the end...

I have a whole house generator and the switch is pretty substantial... If you are out there you hear a loud clunk when it switches... I do not see how it could be wired incorrectly but people do dumb things...

 

[marko]

An interesting subject, but the title led me to believe that your neighbor wasn't happy about something.

 

[Masquernom]

This will be an interesting read... let us know what happens in the end...

I have a whole house generator and the switch is pretty substantial... If you are out there you hear a loud clunk when it switches... I do not see how it could be wired incorrectly but people do dumb things...

Having worked over 30 years in industry, believe me, if something can be installed incorrectly, it eventually will be. I could spend all morning typing up examples.

 

[JoeWras]

Having worked over 30 years in industry, believe me, if something can be installed incorrectly, it eventually will be. I could spend all morning typing up examples.

Or it gets damaged. One of my volunteer crew shot a nail through some siding and directly into an electrical breaker/switch box. It caused both the main electric to fail, and the backup generator to fail. The way the failure contacted the breaker was interesting. It caused the breaker to trip and disallowed the backup to engage. If the nail went somewhere else, I could see a scenario where it causes something to engage when it shouldn't. Who knows? Faults happen.

 

[user5027]

Definite incorrect hook up. Neighbor probably plugged generator in to a home circuit to run it back through his panel (probably doesn't have a transfer switch) and didn't turn off the main breaker to avoid power going out to the main line. This is a common mistake that as you said has bad outcome.

Flieger

My guess is that it’s someone nearby who has small generator and has plugged it directly into a wall plug in order to energize a single circuit in their home.

The OP said it happened within 3 seconds of power going out and doesn't support the time required for a neighbor to start and plug a generator in. It will be interesting to hear what the cause is.

 

[CaptTom]

I'm not quite ready to blame a neighbor. There are failure modes where a downed line or damaged transformer can cause a dramatic voltage drop, but not a complete open circuit.

 

[JoeWras]

I'm not quite ready to blame a neighbor. There are failure modes where a downed line or damaged transformer can cause a dramatic voltage drop, but not a complete open circuit.

That's true.

 

[Zathras]

I'm not quite ready to blame a neighbor. There are failure modes where a downed line or damaged transformer can cause a dramatic voltage drop, but not a complete open circuit.

I would lean this way.

As already said, a few seconds is an awfully quick manual startup of a generator.
Although I have heard of standby generators that take a few seconds.

Any professionally installed solar will have a disconnect reliant on grid power. If the grid goes down, solar production gets turned off.
If someone went the DIY route without permits, I suppose that might be possible.

In any event, I would, as others already have, reinforce contacting the utility to let them know.

 

[Spock]

A defensive product idea:
Todays automatic transfer switch detects grid brown-outs and disconnects. Doesn't reconnect until the grid is stable for X amount of time.
Only modification needed is to have it do the same even without a backup generator attached.

 

[Gumby]

I think the electric company would be quite interested in this event for the safety of their employees who think they are working on dead lines.

 

[Midpack]

As already said, a few seconds is an awfully quick manual startup of a generator.
Although I have heard of standby generators that take a few seconds.

+1, as they should, you don’t want a standby generator kicking on for every momentary power blip - should be by design.

I don’t have a home generator but the last factory I worked at had huge backup generators, by design they didn’t kick on for several minutes (5-10 minutes IIRC), again we didn’t want them starting for short outages. In fact, it gave us time to manually abort a generator switch over if we knew it wasn’t going to be necessary - there were critical process stages where we needed backups (reactor exotherm cooling), but most of the time not.

 

[JoeWras]

DW worked in I.T. with a huge mainframe deployment. The way their power worked was that a battery bank kicked in immediately to keep the power perfect to the mainframes. Then after a few minutes, the diesel generators kicked in and switched over.

It was a fragile system, even though it cost hundreds of thousands. They even had a small roof fire one time when it switched over. Nice: both a power failure and fire at once!

Mainframes don't like it when they lose power.

---

BTW, I've been busy. I'm on hold for over 15 minutes at the power company to talk about this with them. I'll see if I get through and report back.

 

[JoeWras]

Well, I did my duty and reported it.

The agent listened to my story, then said: "Hold on, I need to talk to a specialist."

After a few minutes she came back and said: "You were sharing your neighbor's generator, that's why that happened."

I mean, they probably don't know for sure, but it sounds like this fault is so common they just assume that's going to happen now.