Author Topic: CRAZY Brownout/Partial "Phase Loss!"  (Read 119 times)
MVMH_99
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CRAZY Brownout/Partial "Phase Loss!" « on: October 26, 2025, 02:27:04 PM » Author: MVMH_99
Hello everyone! 

I know everybody here enjoys crazy electrical stories, and I have a good one for you today!  This one is actually about something that happened a little while back, but it is still well worth sharing.

Last year, in our neighborhood, we experienced our first-ever brownout, due to some idiot (people where I live drive like crazy) having crashed into a power pole a few blocks away.  To be honest, I actually found it peculiar that a pole located several blocks away would feed our block, but I guess that goes to show the “interconnected” nature of the grid, at least where I live.  I digress.  Nevertheless, it was a summer evening, and I had just gotten home from work.  All of a sudden, we heard a loud electrical buzzing noise in the distance, which stopped after a little while.

When we got inside, we noticed the lights were dim, and the fridge appeared to not be running at full “strength.”  We also have a smart meter, which was not reading correctly – it was showing a screen with all sorts of symbols and characters, but no actual reading.  This means the incoming voltage to the house was so low that even the meter couldn’t read it!  We scrambled to turn off the power to sensitive electronics/appliances in the house, which luckily were not damaged by the decrease in voltage.  What is also very strange is that at one point, it seemed as though one phase was running at full power, but the second one was not (some lights were brighter than others).  It almost seemed to mimic a lost neutral type of situation, although it truly wasn’t.

Fast-forward about five minutes, and the power went out completely.  There was more buzzing in the distance, and several minutes later, you could hear sirens.  At this point, we knew it was clearly an accident of some sort (which was later confirmed the next day).  A few minutes later, the power came back on again, but the lights were still very dim.  This happened a couple of times before it went out again completely.  It stayed off for a couple of hours, before PG&E was luckily able to show up for emergency repairs.  The good news is that after it came back on, the voltages were all reading as they should have, and everything in the home resumed normal operation.


I’m not entirely sure as to why the falling of the power lines and pole resulted in a brownout as opposed to a full-on outage.  My only guess is that due to how it happened to fall, it resulted in only partial damaging of the lines (until they presumably burned through from arcing), thereby causing them to make only “half” or otherwise unreliable contact.  If so, this would also explain the “cycling” on and off of the power, but perhaps still not the decrease in voltage.  I wonder if there could be any other explanation.  If anyone on here has any ideas, I’d welcome any input!


Anyway, I thought this was pretty wacky to actually experience first-hand!  Has anyone else here ever experienced a brownout before?  I can at least say I’m pretty confident that even if you have, it almost certainly wasn’t due to anything like what happened here!
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Multisubject
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Re: CRAZY Brownout/Partial "Phase Loss!" « Reply #1 on: October 26, 2025, 03:06:10 PM » Author: Multisubject
Very interesting story, that is definitely not a common occurrence. The power cycling behavior is almost certainly the doings of a "recloser", which is essentially a high voltage circuit breaker that resets automatically a set amount of times before finally quitting and keeping the power off. I have never experience a brownout, but reliably once a year the high voltage expulsion fuse right outside my house opens with a deafening bang and then we have to wait to get it refused. Don't you just love overhead distribution?
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xmaslightguy
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Re: CRAZY Brownout/Partial "Phase Loss!" « Reply #2 on: October 26, 2025, 08:47:03 PM » Author: xmaslightguy
I can remember at the place I used to work (large building so 3-phase power) there were a few separate times where there was a partial outage.... one phase went out, one was on at around half-voltage and one was on at full voltage.
That ofcorse caused issues. Refrigerators & freezers don't like running half-voltage!
And 3-phase motors like those in HVAC systems especially don't like such a setup..
Fluorescent lights in the hallway must have been on the half-voltage phase, because turned it into a wild blinky light-show. .lol.
Then there were various that were either on or off.
Stuff like LED bulbs just ran dim.

One of the times it happened I heard the cause was a truck hitting a power pole.
Another I think was road construction.
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Medved
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Re: CRAZY Brownout/Partial "Phase Loss!" « Reply #3 on: Today at 02:29:12 AM » Author: Medved
What surprises me on this story is how long the situation remained: 5 minutes of clearly damaged distribution system, doing who konws what and no protection shut it off automatically? That is the craziest part on it form me.

I consider the grid here as pretty outdated, but this has never happened here, even going as far as into the 80's.
To be clear idiots ramming poles and breaking some wires or causing flashovers do happen. But such crazy situation laststing for more than a second or two, before the power gets completely cut off by the protections.
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