Lights got real dim

[hobbyfarm6]

A couple nights ago we had a really bad storm. Five inches of rain in an hour. I now have ruts all over the place. But that's not why I'm posting. During the storm I unplugged everything because the lightning was really bad. I only things I left turned on were a few lights, a window fan, and my battery operated weather radio. The power went of several times, but it would come back on in less than a minute. This is pretty normal, especially out here in the country. Generally a bright and close flash of lightning will cause this. All of a sudden there was another very bright flash of lightning, and the lights went out, but this time when they came back on, the bulbs were barely lit. Just a dull glow, as if they were getting half or less voltage. These are common incadesant bulbs, not CF bulbs. They remained in this barely on state for maybe a half minute, and the fan motor had a noticable hum. Then they came back on to normal brightness.

I can understand the power going totally off, and know the power company has resets on poles and such, but why did I get this half power thing? I'm glad I unplugged the electronics or I might be replacing lots of stuff.

I know someone is going to ask, so I have 120/240 single phase in the house. This was not something just in my house, both my, and my neighbors yard lights went out.

[hobbes]

This I think is commonly called a "Brown Out". The power station cannot supply sufficient voltage, so basically instead of seeing 120v you may be seeing say 40 volts only. Hence everything is sort of dim.

best, Mike.

[Steve Barker]

Generally this will happen when a tree branch arcs out a line down the road a ways. You may have actually seen the light of the arcing and not lighting. Lighting could have also hit a transformer on your line somewhere and fried it out.

steve

[bud--]

Could be a power line was knocked to the ground, resulting in high current, producing a voltage drop, and a fuse finally opened.

Or a transformer shorted and the fuse finally opened

As you lower the voltage on an incandescent bulb, the brightness goes down a lot faster than the voltage.

-- bud--

[John Reber]

Or a neighbor back feeding onto the grid from incorrectly hooking up a generator.

[EXT]

Since the power came back after about half a minute, I would say no fuse blew on the line. Instead there may have been a major drain of power such as mentioned below with a branch hanging onto the line but not creating a dead short that would have blown the line fuse. With a major draining of power, that left you enough to make the lamps glow, possibly the wind blew the branch back off the lines allowing full power to be restored. Possibly, if the branch stayed on the line much longer the fuse would have popped, and you would be in the dark until a power line worker replaced the fuse.

[dpb]

Not a replaceable fuse, no, but a breaker may well have opened (and probably did) to give the line a chance to clear of whatever was the problem.

When it reset, sounds like a temporary sag which isn't too uncommon on long lines, particularly if there might be a fairly sizable load somewhere off the particular affected line. High inrush currents of all those A/C's, fridges, etc., plus any other large single-point loads if any all add up to quite a chunk...add that to a possibility of a partial drain not quite cleared yet and not at all uncommon for it to take 30 seconds or so to recover...happens to us on the rural lines quite often.

--

[JohnR66]

Could have been a tree as others have said, but it could also be a phase loss condition since your power is a single phase from three phase distribution. The commercial building I worked in would often lose a phase thanks to a squirrel or some other accident that would trip on of the phases. Some of the outlets would go to about half voltage until full service was restored. John