Power line arching and line failure

[TheMrpanda54]

tweet tweet tweet tweet tweet tweet tweet ... BOOM!

[TheCessnaDriver]

mmm, crispyness

[randylaheycoreytrevo]

....that's why you should run a seperate primary neutral...hopefully it's tied from both ways.



[randylaheycoreytrevo]

There goes the noodle.



[hunterlegoking]

How did this happen?

[sonconmas]

Cool vid! BTW, what's the sound at 0:19?

[ribeekeeper]

@sonconmas - A fire truck that was on the scene.

[123Jus1]

wait, i thought the electrical lines were the three at the top, Hotwire + , hotwire - , and ground

[TheChipmunk2008]

@123Jus1 The three at the top are the high tension primary phase lines. Depending on what area (and indeed country) you're in, they can vary from 2400v in some parts of Canada, up to 33,000v in parts of the UK. If you notice, the transformer is connected to just one of them, providing single phase :-)

[123Jus1]

@TheChipmunk2008 so then the thick ones at/ on the middle are cable, phone, two hotwires and a ground? + sometimes a fiber optic?

[TheChipmunk2008]

usually the sequence goes primaries at the top, then low tension at or about the level of the base of the transformer, then everything else lumped together below that (cable tv, phone, fiber, etc.) If you notice at the end of this video, when he pans to the right to follow the 'dropped' cable, you can see 2 thicker cables below it that are offscreen or not present on the pole with the transformer, those would appear to be the cable/phone feeds :-)

[123Jus1]

@TheChipmunk2008 thanks for the clarification

[RussianBear842]

Коротыш-тыш-тыш, коротыш.

[Mofoe2001]

SELF DESTRUCTING.......BZZZZZZZzz ZZzz pop zZzZzzz pop....SELF DESTRUCT COMPLETE (power down noise)

[randomvideowatcher]

That's what you call the hotline. The wires died fron too many hertz. They should get a neutral party to fix the wire. The wire is nervous...it was smoking. It's always good to study current events. The incident was revolting. A shocking event for the tree. It was beyond beleaf.

[tall32guy]

@randomvideowatcher LMAO!!!!

[nodoubtpetersbuilt]

Look again! The neutral never severed. Both hot legs came into contact. Probly in that tree? Heated up and melted. Saw the same thing happen once. Only it wasn't a tree. It was a rookie mistake by a lineman. The cutout "fuse" never blew.

[EvilKiteeProductions]

goos thing no one used the phone *ring ring ring* *KABOOM* <_<

[wasteconnectionsdude]

that looks fun!

[myryonspoof]

pretty nice conversation in the comments section.

[ApolloWasReal]

Note also how even the three wires from the transformer secondary terminals dance around as the high currents produce some pretty intense magnetic fields.



[quantumbits]

It worries me that the neutral on the secondary is also used for the "neutral" on the primary. There is an earth ground at every pole but as we all know the earth is a very poor conductor.

[REWYRED]

@quantumbits  True but depending on where you are in the circuit, the neutrals are all connected in a grid so if you had an opening in one of them, there is still a path around the break. In my neighbourhood , being at the END of a line , if the neutral were to open up, there are still alternate neutral paths, between ground rods, through customers neutrals, along the water lines used as grounding and back up elsewhere... Sounds bad but I have seen it happen.

[quantumbits]

@REWYRED Thanks for that. I see your point. .... Hmmm Still it makes me want to put three ground rods at my service entrance!

[REWYRED]

@quantumbits Ah! we dont use rods here anymore for resi services if we do not have a water line.. ground "plates" are the norm.. galvanized chunks of steel that are equivalent to 2 rods.

[quantumbits]

@REWYREDHmmm.. where is here and How big are these plates?

[REWYRED]

@quantumbits "Here" is Ontario Canada... Hamilton to be really specific.. and the plates are 12"x18" roughly... they must be buried no less than 18" and in contact with "undisturbed" soil, but the code around here allows us to use various other methods of grounding such as water pipes, rebar within concrete, copper conductor of a given length set within so many inches of the bottom of a concrete footing etc..

[ApolloWasReal]

@REWYRED How long do those buried plates last? If they're galvanized steel, you know they're gonna corrode eventually. In fact, here in southern California one of the local modifications to the NEC is to require that all buried conduit be PVC. Buried steel conduit is banned because it corrodes so quickly. Maybe buried steel lasts acceptably long in cold Ontario?

[REWYRED]

@ApolloWasReal We are allowed to use galvanized conduit and bury it but it must be rigid ( Heavywall).. No one ever does anymore because it is just that much of a pain in the ass and it does corrode. As far as the lifetime of these plates, probably as long as a galv ground rod, OR long enough to outlast your service... Some applications I believe call for copper clad rods ONLY, such as transformer vault ground grids and the like

[ApolloWasReal]

@REWYRED Interesting, thanks. I'd think that unless you really needed a conductive bond with the soil, as in a ground system, you'd want to use PVC conduit anyway, right? Lasts forever and is much cheaper, lighter and easier to work with.

[ApolloWasReal]

@quantumbits Here in California the practice is different. Every distribution transformer primary is wired phase-to-phase, not phase-to-neutral. The transformers all have two insulators on top rather than one. I don't know if this practice is followed in any other states, or why it's done here.

[quantumbits]

@ApolloWasReal Interesting, I dunno either. That's a single phase derivative of the delta system. It may have to do with WHEN the system was initially installed. Here, we only see phase-to-phase primary (delta) only at commercial locations where multiphase is required.

[ApolloWasReal]

@quantumbits The phase-phase transformer primary connection seems to be universal in California. I had thought maybe it's standard practice in dry areas (since grounds on neutrals might not be as effective) but Nevada seems to use phase-neutral connections. Maybe it's California state law?

[ApolloWasReal]

It's really interesting that at first only the neutral heats and expands. After it breaks, then only one of the phase conductors does the same. I'm trying to figure out how that happened.

With the loss of that neutral, I'd expect some appliance-damaging voltage surges in the nearby houses, depending on how effectively their neutrals were grounded. Were there any?

[quantumbits]

Respond to this video... trying to figure that out to. Wow that old drop line needed to be replaced a long time ago. Sometimes other transformers secondaries are linked together with these drop lines.

[ribeekeeper]

@ApolloWasReal I turned the entire service off at my house when I first heard and saw the arching. That was about an hour before it finally failed.

[ApolloWasReal]

@ribeekeeper That was a VERY wise move!

[SSGTrentsXe]

@ribeekeeper Smart man.

[Hemingray]

@ApolloWasReal Neutral is still intact. the other two wires are phase. 

[ApolloWasReal]

@Hemingray Ah so. I guess I had assumed the neutral was in the middle.

[TheChipmunk2008]

@ApolloWasReal Apollo, I THINK some of the shorting is offcamera to the right, maybe the neutral was corroded at the left end due to water damage, causing a bit higher resistance than the rest of the line? Pure guesswork, but it's the closest I can guess!

[nakayle]

The transformer primary fuse should have blown before all this happen.

Somebody must have overfused it.

[djrimenica]

@nakayle Not really, cause the transfor. asume that short circuit as a load... the fuse that should have blown its the secondary side.

[nakayle]

@djrimenica Pole transformers don't have fuses on the secondary side- and if you look at the transformer towards the end of the video you can see where the oil has boiled out over top- indicating it has been been badly overheated by excess current which a properly sized primary fuse would have prevented. This transformer will likely have to be replaced because of damaged winding insulation. A lot cheaper to replace a fuse.

[quantumbits]

@nakayle Good observation on that oil. I didn't notice that.

[ApolloWasReal]

@nakayle What's a typical transformer rating, and how big should the primary fuse be? I know that would depend on the primary voltage -- let's say it's 7.62 kV from phase to neutral, which seems common in the US.

[MSCompuServ]

Pulling too many amps. You shouldn't ever go over 100A on a 240v line.

[OnnomonnomonnO]

oops..

[c0rrupts3ct0r555]

too bad it wasnt the line BEFORE the transformer, would have been a much nicer arm and a loud hum.. thats about 240 volts because its AFTER the transformer..

[jro9001]

did the lights go out?

[mattsoftnet]

@jro9001 nope, I don't think they did. they have wireless power meters now

[flakmonkey47]

Short out!