Neightbor Overloads Neighboorhood's Power System
This isn't directly ham radio related, but I thought it'd be a good warning to what else can happen with electricity even if the person causing the problem isn't shorted out himself.
This guy was pulling shingles off his roof, accidentally caught one of the power lines running to his house, it swung into the other, fused and caused at least three other houses to have significant damage.
*Note, this is the first time I've posted a news topic, so I hope I'm not doing anything wrong here.
An interesting read--and a warning to hams about what could happen if the incoming power lines were to be shorted--by a person installing an antenna! Keep in mind that the 220 volt 2 phase power coming into a home is nothing to fool with if you're not sure what you're doing.
In my area, the incoming power is a twisted threesome, two hot and one neutral, but some areas still don't do things in that manner. That is evident in the story. The power company has to share some of the fault for leaving the incoming wires bare, at the lease they should be covered by insulation especially when going up to a private residence.
The guy will probably lose his house anyway, or will have to take out a mortgage to pay the power company because his insurance company isn't going to pay this bill--not when the facts of the story are told!
Not exactly ... it's still single phase power even though there are two hots. The voltage on the hots is 180° out of phase, but still the SAME phase.
the 220 volt 2 phase power coming into a home
But the same warning still applies, regardless...
That story just does not sound right. Why didn't the secondary fuse on the transformer open up with a dead short. I have seen that happen and they go BANG!!!! in short order (no pun intended). Also why would the neighbors wall sockets start arcing? It was a short condition not an over voltage condition.Why would his stove magically turn itself on when the switch was off? I can see no way that the primary would make contact with the secondary as the primary would have to fall onto the secondary. The secondary does not "flip up" into the primary even with the force resulting from an arc. If the transformer was to short primary to secondary then an overvoltage condition would result but the fuse on the secondary should have opened up before the transformer short occured with the amount of current that shorted 220 lines would draw.I know that electricity can do strange things but something still does not sound right. If it did in fact happen as the story says then the power company should be at fault as well because of the failure of the fuses to open.
Primary Fell On Secondary
The usual cause of a disaster like this is a high voltage primary falling onto a secondary.
A few years ago here, during a heat wave, our ancient power lines actually melted through in places and fell into the street. Luckily, no fires were started and no injuries or damage were caused. Just gravity doing its job.
After a couple of days, we got all new "infrastructure", inlcluding a flatbead semi loaded with a dozen or so new pole transformers.
I agree. There has to be more to the story than the original story tells. There's no rational reason why shorting the wires coming into normal residential feeds should cause HIGHER voltage, if the original electrical feed was properly installed. (Unless, of course, the person causing the problem had some sort of special, "industrial" feed into the residence, with more than the standard 240 Volt (120 V.- Neutral - 120 V.) feed.
Originally Posted by kf6iiu
And the feeds (but not neutral) are supposed to be insulated from the house to at least the pole. In most areas, the feeds are actually twisted around a steel messenger cable, so bare wires are an impossibility.
Over here, I was watching the news one morning and,,,
Originally Posted by VE1IDX
Sounded just like a shotgun going off. The power went out with the pow, so I went outside and my neighbors were out there too, scratching our heads trying to figure out what happened. The power company came over and the guy up on my pole right behind my house said, "Well, that's the end of that squirrel". I asked him what he meant and he pointed down at the ground by the pole and there was this burnt up squirrel there. The squirrel shorted out the connections from the transformer to the pole. And the line fuse is also on my pole. He said that the squirrel was climbing around and shorted himself out with the connections on the transformer. That bang sounded like a shotgun going off when the fuse blew. In fact, I thought that's what happened that someone that doesn't like me very well shot my fuse at the pole
I spent all my years when I was young wishing I was older. Now I spend all my years when I'm old wishing I was younger....
Perhaps they have them in Canada, but in the US, usually only the primary is fused.
Originally Posted by VE1IDX
It was an over voltage condition after the neutral opened up. Normally, NEMA duplex outlets (5-15R and 5-20R) are rated for 125VAC, not 240VAC. Exceed the rating, and failure by arcing fault is possible.
Also why would the neighbors wall sockets start arcing? It was a short condition not an over voltage condition.
Electronic controls that use the neutral to derive 120 volts and got instead a lot more than they could handle was probably the reason.
Why would his stove magically turn itself on when the switch was off?
Not so much for the fuses not operating so much as the neutral opening up somehow. An arcing fault can continue for quite a while sometimes before its solid enough to take out the transformer primary fuses.
If it did in fact happen as the story says then the power company should be at fault as well because of the failure of the fuses to open.
It is obviously when a kid rubs his shoes on a rug in the winter and zaps his little sisters mitten covered hand with his own mitten covered hand.
k4kyv What is an inter-mitten arc?
I've seen this during storms with tree limbs. They will nearly contact the line but not completely, causing some arcing but not completely. Then when the tree finally makes actual contact with the line there is the failure or trip.
Originally Posted by w6em
I'm personally thinking there is more to the story than we're being told. And who the heck would reset a breaker after watching his lights or appliances do something obviously well BEYOND normal operation? I think if I saw something like that happen I would perhaps stop for a minute and think before I went and started reconnecting my house to that kind of power.