Absolutely amazing nobody was killed. I wonder what the conversation was like on the bus keeping folks in while there was fire encroaching. Even if you don't touch the conductors, potential gradient can ruin your day.
In this situation it means that the ground (or water) near a downed power line is charged, but the voltage drops quickly as you get further from the conductor (that's the potential gradient).
It can ruin your day if you walk towards or away from it, because your feet might bridge two areas of ground that have a 10kV difference.
Your body being a bag of salty water makes a much better conductor than dirt, so the voltage takes the path of least resistance.
The safest advise is don't try to traverse the ground in that situation at all. However, if you must, the advice is to hop with your feet together or shuffle with very small steps (with the understanding that if you fall you're almost certainly going to fry).
Minor quibble: This implies that electricity only takes the path of least resistance. Electricity actually takes all available paths in inverse proportion to the impedance of the paths. This is why grounding rods don't keep you from being electrocuted. I'm looking at you, sketchy lamp-post.
Good clarification. When I was a kid I found out that standing on the edge of the kitchen sink and touching the pull chain on the lamp in the soffit overhead would 'tickle'. I was so proud when I told mom and dad! :P
Bad idea. If you slip even once, suddenly you don't have "just" the 1m of an ordinary step but 1.5 or 2m... and the longer, the greater the voltage gradient.
In theory if you leap from the bus such that you are completely in the air for a moment, you won't be in contact with a conductor and the ground at the same time. (Given enough voltage, electricity can cross the gap to the ground, but if there's a fire you gotta do what you gotta do.) You then have to keep hopping with your feet together or shuffle-step away due the the potential energy difference in the ground.
A problem is that many people who use a bus are not physically capable of a leap. They may be elderly, disabled, pregnant or simply be very small children.
I'm pretty sure that even almost invisible smoke can already cause significant trouble in this respect. Partly because particles of smoke themselves can be electrostatically attracted to objects under significant voltage, so even low density smoke can concentrate itself in problematic places. See Figure 3. and the text above it in https://www.osti.gov/servlets/purl/3313 .
We learned as kids stay put unless absolutely having to leave the vehicle. If you had to leave because of say a fire you were to keep both feet together and literally hop away like you say not walk. This is going way back it seems to make sense but I haven’t checked the source on this.
Shuffling is recommended over hopping because you're less likely to fall over. Shuffle in small movements keeping your feet on the ground and close together.
Where did you learn this? Were they specifically teaching you want to do if a power line lands on your car? That seems like a pretty rare situation. Or was it about electric cars or busses?
Is power line landing on things all that rare? There's lots of power lines on poles in cities around the world. Also very strong winds like to down trees, which then sometimes down such powerlines.
I am from denmark, we have practically no power lines above ground except for the occational high voltage lines which they are also planning to bury. By 2040 it will only be allowed to have 400KV lines above ground.
I’m grade school. I am in Canada and almost all our power lines are above ground. Yes it was specific to if a power line landed on your car or even if it crashed beside your car and you had to get out.
I don't know anything about urban fire fighting. It seems like the primary block to rescuing the civilians is that the power is still on, and they had to wait for the power to be off. That makes me think that firefighters, if they can't already, should be able to either 1) turn off power on site, or 2) easily contact someone who can do so remotely.
We can easily contact someone but they can’t do it remotely. The power company needs to come on scene. Isolating power is a lot more complex than it used to be because of solar installations. We can never be sure that every building’s solar is properly isolated from the grid.
In these cases where people need to be evacuated from a vehicle that’s live due to power lines there are protocols for doing so, it’s just more risky. We need to ensure they jump from the vehicle so they’re never touching the vehicle and the ground simultaneously. We also need to get them to shuffle to make sure there’s no step potential between their feet. Neither is easy to guarantee with a member of the public probably panicking.
Yes, and this is why grid-tied solar installations go out when the power goes out. You need a battery backup for energy independence. This catches a lot of first-time solar owners by surprise if they don't do their research; they think that solar will mean they don't lose power if there's a daytime power outage, but unless they also get a battery they lose it anyway.
Would a battery really sove that though? If regulations say that anything feeding the grid should shut down if it detects an outage of incoming power (I'm still perplexed as to how you'd measure that on the same conductor, but it's not really my field), wouldn't a battery feeding the grid have to do the same. And if you have the cut-off "upstream" of your house (so your house can still get power from the battery, but the grid doesn't), then why couldn't you do that just with the panels and no battery? Obviously a battery would be better, but in terms of cutting power in an outage, I can't see a difference.
When the grid goes down the panels power the house if there's electricity demand, or the battery if there's not. The reason this doesn't work without the battery is that in any closed circuit, electricity production must equal electricity demand at all times. The grid can aggregate millions of households and then has peaking power plants to adjust electricity production to meet electricity consumption. Residential solar panels have no such mechanism - if it's the middle of a summer day and the only appliance you have plugged in is your computer, then that computer is getting your ~4kW of power and is gonna fry. Add a battery and any excess power instead goes to charge the battery.
When the battery is full, the grid is off, the house isn't drawing anything, and the panels are still producing, then the circuitry does some trickery to just disable the panels. (I think the inverters actually feed the power back 180 degrees out-of-phase so it cancels out the other power coming from the panels, but the details are beyond me.) Note that the panels are actually disabled at this point, though - they're effectively producing nothing, not just producing less. That's why this doesn't work without the battery - you can break a circuit entirely to stop power from flowing, but as long as the circuit exists without energy storage, power in must equal power out.
I imagine it's two separate inverters, a solar inverter that cannot function without grid power and a separate battery inverter. The two feeding the house circuit via a break-before-make transfer switch reduces the chances of accidentally back-feeding the grid because the isolation switch didn't work.
It's part of the requirements, but that doesn't guarantee it will happen. Equipment can fail to operate correctly (or be misconfigured) and you still need to verify that the power is correctly isolated before doing work on potentially live conductors.
We can never be sure that every building’s solar is properly isolated from the grid.
Is this a new problem? Standby generators seem pretty common in the SF Bay Area - you can tell when the power goes out by the sound of generators in the neighborhood. I'd think that there are at least as many sketchy generator installs as solar installs.
Generators isolate themselves from the grid (unless they're installed extremely irresponsibly.) Part of the point behind solar is that it feeds power back to the grid because the operators are the only ones with the infrastructure to deal with the excess.
Grid tie inverters do the same, no power company would allow them otherwise.
Generators don't isolate themselves, a code compliant generator will have a transfer switch that makes it impossible to backfeed the grid.
The problem with generators is that anyone can buy one for a few hundred dollars and hook it up to backfeed their house without a transfer switch because a transfer switch is expensive to install and "I'll never forget to turn off the utility breaker before I turn on the generator"
At least you need to get approval (and inspection?) from the power company before you can utilize net metering with solar, but anyone with basic electrical knowledge (or access to Youtube) and $20 can rig up a suicide cable to backfeed the grid from their generator.
While that's true most generators are only rated for a few KW and most circuits they're hooked up to the bad, backwards way are several hundred KW i.e. their local grid that has been disconnected. So they would trip their breakers immediately and go offline or else stall or melt.
Unless I'm missing something of course. Which is entirely possible.
If everything is working perfectly, then sure. But maybe that cheap 30A generator isn't running well enough to trip its 30A breaker and it's trying its best to backfeed 20A of current into the grid. Or maybe the other 5 neighbors on his pole transformer tripped over to generator or solar, so that one guy is able to power his pole transformer while the lineman is trying to work on it, or maybe he can't figure out why the breaker keeps tripping, so he keeps resetting it, only to have it trip again a second later, meanwhile he's sending surges of current into the grid.
Utility workers will normally ground de-energized conductors before they work on them, but they need to do it perfectly each time to protect themselves from backfeeding.
You can turn a generator off, and power in lines ends. Solar is different in that there is no way to safe a panel. If it’s receiving sunlight it’s generating power. That’s a pretty different paradigm then any other electrical system currently used on buildings.
Inverters should be equipped with automatic anti-islanding, which causes the inverter to shut off when it no longer detects power from the grid supplier (there are a few different ways to detect this). A lot of inverters built for grid-tie applications can't function without a mains connection anyway because of the way they track the frequency (unity power factor output).
There can be a danger to first responders on the DC side of the inverter, which may still have a high DC potential from the panels (string voltage can be 100vdc and up). Fortunately, code in a lot of areas (in general areas that have adopted a 2014 or newer NEC) requires a "DC Rapid Shutdown" feature on new solar installations. In these systems there is a small module on each panel that detects the loss of a signal from the inverter and disconnects the panel from the string, eliminating the shock hazard from the panel cabling. This way the panels just get hot instead of producing power. That's only going to be on newer installations but at least NEC requires a big "DC Rapid Shutdown" sticker on the inverter if so. These systems can also be useful to avoid "cold start" overvoltage problems.
Beside automatic disconnects, every solar installation I've seen (Boston area) has a readily accessible grid disconnect colocated with the inverter on the side of the house. As in, I could walk up to anyone's house and disconnect their solar from the grid with no special tools. (I know they all have automatic disconnect as well, because by and large the majority are the same brand -- SolarWave. Not sure about microinverters though.)
My understanding is that inverters are required (by electrical code among other things) to disconnect from the grid when grid power is lost.
Malfunctioning (or illegally installed) inverters are possible but shouldn’t be a common problem.
Yes, but in firefighting, a lot of the time we are up on the roof, cutting holes in the attic to let heat out of the building. The invertor will shutdown power to the inside of the building, but the line from the solar panel to the invertor is still hot. That line can be cut through as in a lot of installs it can be run through the attic. This line is never discharged but is always hot. As well as all of the lines between the panels. These can ground out in the building and cause electrical charge in objects that would be 'off' if it was a traditional power hookup that all power to the building can be shutoff from cutting the power grid building service. If one of those lines is cut, and a firefighter sticks a pike pole into the attic and touches that wire it could electrocute him just as readily as if the building was still energized by the power grid.
I wonder how effective grid isolation/'anti islanding protection' is, when the 'island' is big enough, and contains multiple grid tied solar installations.
It probably comes down to how they detect a grid outage.
But I can think of some scenarios where the solar inverters can see each other on the grid, and assume the grid is still up
I think they usually look at the frequency and magnitude of the voltage, if it is outside of say 57.5 to 62 Hz or 80-120% of nominal voltage the inverter probably decides it is no longer connected to the grid.
It is possible, but extremely unlikely, that a distributed generation island gets lucky that there is enough generation to meet the load on the island and it can respond fast enough to keep frequency and voltage within range when the island forms.
Dumb question, but how do you measure the voltage on a conductor if you're also putting out that same voltage on that same conductor? For the frequency I can imagine you could probably detect a frequency shift with an independent oscillator, but even then, since the inverter's sine wave is generated electronically, I can't imagine it would follow the usual laws that rotary generators do (frequency changes when supply and load are mismatched).
(I'm a software engineer with no formal EE education, so "it's complicated, go read a book first" is also an acceptable answer)
It is a good question and I don’t design inverters so I don’t really know.
I imagine an inverter with one solar panel behind it can’t muster enough oomph to back feed a sizable chunk of distribution network - if it tried it would not be able to maintain nominal voltage. Say the load of the neighborhood is 500 kW, that’s 1200 A at 240V, which the inverter can’t supply unless there is 500 Kw of solar panels behind it. The 500kw load at 240V looks like a 0.2 ohm resistor to the inverter - essentially a short. Actually looking at the impedance of the network is one technique protection relays use to detect line faults.
Maybe the inverter can’t sustain the nominal voltage when feeding essentially a short so the voltage will be less then nominal and then it knows it is operating outside or normal conditions.
I can’t imagine a scenario in which the inverter could maintain nominal voltage at its terminals with a 0.2 ohm load looking out, if there is 240V across 0.2 ohm then there is 1200A through the 0.2 ohm.
In summary despite putting out voltage it will not be able to maintain the desired terminal voltage.
For frequency I understand most grid tie inverters somehow follow the grid frequency as opposed to generating their own.
I'm surprised fire departments don't have equipment for emergency grounding of power lines, e.g. something that creates a ground connection and some form of launcher that throws a steel cable and/or mesh across the line.
I know this exists for subway systems with a third rail, I'll edit if I find the video.
Or insulating mats for evacuation, potentially with steel conductors underneath them to avoid step potential.
> We can never be sure that every building’s solar is properly isolated from the grid.
This sounds like a risk that needs to be balanced against other risks. If the fire on that bus had got to the point that it was clearly going to burn the passengers alive, it surely would have been better to allow them to walk over a possibly-electrified area? That's assuming that the responders wouldn't have needed to walk over it though.
Yep, absolutely. Chances are if there's a going fire there won't be any isolation at all before the occupants need to be moved. In that case you try and extract them from the vehicle without letting them be shocked. Never touch the car and the ground at the same time. Shuffle away from the incident rather than walking to limit step potential.
Ideally, stay in your vehicle and wait for help to disable the power. The vehicle's frame will protect you as long as you stay inside the car.
If it's necessary to leave the vehicle (e.g. due to fire), you have to avoid being in contact with the vehicle and the ground at the same time. You have to do a funny looking hop into the air.
There's a similar problem with people using male-to-male cords (suicide cords) on their generators too? Plug a portable generator into your house this way and now it's pumping out electricity and not purely consuming it.
It should be obvious that before you do so you should turn off the main disconnect. Otherwise you're electrifying the line for utility workers and also powering (half of) your neighbor's house backwards through a 20A circuit from your little generator, which won't work out well...
Some departments are trained in shutting down the power to a building via cutting the service line to the building. LAFD does this as response times for power companies are long.
This incident involved high voltage lines which are a different problem. Taking these down requires a bucket truck and specialized tools and training. Firefighters have a lot of training but most of us stay away from electricity. Not to mention they would essentially have to have a specially trained crew that is trained and educated regularly for what are once in a decade type incidents.
Scenes like this are an extremely rare situation, more then likely why it was highlighted in this group. Firefighters enjoy looking at cases like this and thinking about how they would deal with it in their jurisdiction.
that reminds me of the time the construction crew my brother was working with opened a buried gas line, a small one used to supply a group of house. The firefighters and the police were quickly on the scene, but they could only secure the area (creating a nice trafic jam), because apparently firefighters in Paris (or France) aren't authorized to close gas leaks and have to wait for a worker from the gas utility to do it, I guess because there's been accidents when firefighters tried to do it themselves? And so the worker from the gas utility worker arrived 15 min after the firefighters, while the gas continued to spew from the ruptured pipe, and closed the pipe using pliers.
Why are these local power lines up in the air on such low poles? Shouldn't they be buried when in an urban environment? I've only ever seen power lines up in the air when crossing open country, and then 50m or so up in the air.
This is fairly common across the US (based on your use of the metric system I’m guessing you’re not familiar with US cities.) About the only areas with buried lines are high-density urban neighborhoods and wealthy suburbs.
Some places on the coasts bury them as well. My wife grew up on the coast and it wasn’t uncommon to go a few days or more without power each year because wind storms would knock over trees onto the power lines. They’ve since buried a lot of their lines.
It's not unusual for rural and suburban neighborhoods built since the 1970s to bury their powerlines. Even in nowhere Appalachia where I grew up that was very normal.
Many of them in Florida on the east coast are also buried to lessen hurricane damage to infrastructure, but of course the main arteries coming from the power plants are always above ground.
In Slovakia all new construction must have underground power lines. Not only that, hanging anything in the air (like fiber) across the street in all residential areas is banned. But only few decades ago it was common and there are still active 240/400 volt power poles everywhere. The major reason is probably winter icing.
> "I am curious as to where you live where underground is the norm?"
It's very rare to see above-ground power lines in UK towns and cities. You do see them in more rural locations.
(Some UK towns do have broadband cables running on poles, installed in the 1990s/early 2000s and typically splayed out in star configurations to several houses from a single pole. They're very ugly!)
To further add on to other commentators, wooden utility poles are cheap in North America and expensive in lots of places in Europe. Wooden utility poles are made of a solid trunk, not smaller pieces of wood that have been attached together. North America has lots of long straight pine trees to build utility poles out of. European forests have lots of thin or bendy trees which don't make good utility poles. Much of Europe has been denuded of its natural forests.
I remember back in the 90s in Finland there still used to be overhead medium-voltage powerlines in lower-density urban areas; those are practically all gone now, replaced with underground lines. In higher-density areas underground was the norm even back then.
Many HV trunk lines (ie. tens to hundreds of kV) are buried as well, and those that aren’t, of course have wide buffer zones to avoid being hit by errant cars or falling trees.
In the countryside (of which there is a lot in Finland), overhead lines are much more common due to the cost of burying them all. Still, it’s increasingly being done because a few storms in recent years left thousands of rural residents without electricity for days or even weeks – and such storms are only becoming more frequent while our lifestyles are getting even more dependent on electricity.
Burying all those lines is of course expensive, and the expenses will ultimately be paid by the consumers. There has been some pushback due to this – transmission fees have gone up a lot in the 2000s and utility companies are accused of using the costs as an excuse to inflate their profits.
Above-ground pole infrastructure is considered an eyesore by a lot of municipalities, so it's common to require that new subdivisions bury everything for some decades now.
I can see the appeal for urban zones to have new underground high voltage lines (even though it's not ideal from a technical/operation standpoint) to appease land owners, who don't want big new easements for overhead transmission eyesores in their backyard.
That being said, in a typical neighbourhood it's still wires everwhere to the house. I even went as far to drop the little man in google maps and have a peek. Wires everywhere the eye can see!
Same in parts of New England. It's not too unusual to lose power during storms (especially ice storms), but it's typically restored within a few hours.
My understanding is that it's only economical to bury utility lines when there is frequent enough inclement weather to bring them down, which definitely isn't the case in San Jose.
Even then it's not worth it, unless there's some unique risk or liability they're worried about, like near airports.
Retrofits in urban areas are especially expensive, because any good contractor knows there's gonna be unknown problems once you start digging.
Most places that have underground electric in the US have it either because it's mandated by local code or because the original developer was willing to pay for it.
Hypothetically, enough bad weather would make burying it economical, but I've never heard of any particular instance where that was the case.
There are a lot of interesting differences in the basic grid designs and layouts that are a result of the 120 vs 240 voltage differences. Everything from number of transformers, to distances between substations, to the required line separation and clearance from ground.
It all results in fundamental cost differences, that were originally calculated based on density and distances, with US being low density/ large distance and the opposite for the UK.
I'm sure there's related consequences with line burial, but I don't know if that's the reason it's so common in the UK.
Wooden utility poles are made from a single piece of wood, usually the trunk of a pine tree. It's cheap to toss a bunch of them on the back of a truck and drive them to wherever, but they're typically longer than a cargo container, so putting them on a ship is annoying.
The forests in North America has lots of tall, straight pine trees but there are fewer forests in Europe and what forests there are tend to have more deciduous forests, where the trees are shorter, narrower, and ... squigglier.
You could have shorter poles and fit them into cargo containers more easily, but now you're stuck with short utility poles. Concrete or metal utility poles are a thing, but they're more expensive.
All, wooden, concrete and metallic poles over a concrete block are common in Europe. Sometimes is buried, other not. Maybe is not the best solution where the phreatic water level is too high (i.e. most mediterranean cities in the coast).
I suspect this is a big component: uk population density: 281/km2; us population density:36/km2. Obviously not a perfect comparison because density is highly variable, but the US is just so so much more spread out than european countries.
2. I don’t think so. But the way way people describe the geography here is weird. Usually people say it’s the southern end.
3. It’s pretty sprawly, car is king, generally the threat of earthquakes and nimbyism has resulted in low density. I doubt ‘thousands’ though I’m not clear on your units.
4. Highly doubtful. The super-rich mostly live in the suburbs or exurbs of SJ, where it’s cooler (temperature wise) and less urban. Los Gatos, Mountain View, Palo Alto, Woodside, Menlo Park, Atherton, etc.
The electrical grids in general were fundamentally designed differently from country to country, including the voltage difference.
That took into account what was cost effective from the perspective of large scale deployment, and then individual elements are designed from (and are intertwined with) everything downstream from that. So even if two cities (one US and one UK) were/are nearly identical, the resulting grid is going to end up being laid out very differently.
The neighborhood in question was built in the late 1960s, underground has been the default for a few decades now but this neighborhood (along with many others through SJ) is just all old construction. There's no real justification for moving the power underground, even in rich neighborhoods most streets still have power via poles unless they're relatively new.
That explains things - in my experience I have seen money as the most conspicuous main barrier in the Northeast. Get above a certain threshold of wealth and even in sparse areas they go underground and poorer areas can get a bit more density than usual before being forced underground. A suburb with power lines is on the lower side of middle class. An urban area with power lines is practically a red flag for poverty for the two go together.
Reminds me of the joke about cancer risk and lowered IQs and power lines - the mechanism of the damage is insidious - it doesn't act through radiation but through lowered property values.
It's economical for new developments. I lived some years about a mile outside the Washington Beltway, in a rowhouse development built in the mid-80s. Everything had been done on the cheap, but the utility lines were underground.
Which has gotten very bogged down. Undergrounding in San Francisco has all but stopped because of the expense. More ominous is the Palo Alto experience. Quite some time ago, like late 60s or early 70s or there about, Palo Alto undergrounded its utility lines. Since then the combination of clay soils and earthquakes has done enormous damage to the point that the City may have to rebuild their entire utility infrastructure. Seeing Palo Alto confront this enormous unexpected expense is giving pause to local governments all over the bay.
getting downvoted is no reason to keep to yourself :/ its people moderating the overall discussion, not trying to punish you or silence you or something (getting flagged is another matter ofc...)
That goes against my intuition. Everything standing about the ground is bound to have things fall over it in an earthquake. Power lines could be much safer under the ground.
From a friend of mine who was trying hard to get the “unsightly” utility poles buried underground - it was just a lack of interest and funds. Just not a priority here.
Almost all new neighborhoods have utility lines buried.
Earthquake or flood so severe that it damages underground power line, damages water and sewer pipes even sooner. So in that case digging must be done anyway.
I don't know what the power-grid considerations are, but much of the SF Bay Area is on fill or other unstable ground which is subject to liquifaction and severe movement in seismic events.
Undergrouding local transmission might increase overall risks of outages / cost of repair.
Here in my area of Canada it's very rare to have underground electrical power lines. So rare that there was a study using a small town (in New Brunswick?) to research the cost, maintenance, durability of doing so. That was back in the 70s or 80s. It was a unique situation that didn't seem to catch on probably due to the cost.
I don't see that the bus was knocked over. In the photos, the bus is upright and there was no mention of it tipping. It got pushed off the road, and a power pole was knocked over.
My mistake, I misread it. Although, if you're going fast enough to push a bus (an extra-long, bendy bus at that) off the road, it still seems like you were going rather fast for in town?
Each accident is different. The wreckage of the SUV doesn't look like it hit all that hard. It struck the left front corner of the bus. In doing so it may have pushed the wheel, or caused the driver/steering wheel to move sideways. Either could cause the bus to briefly drive itself off the road more so than being directly pushed by the SUV. The bus does seem to have been moving at the time of impact.
I just saw a video of a man who was rescued by police from a burning vehicle. He suffered a medical incident while back his truck up and ended up flooring the gas as he got into his parking spot. The tires spun high speed while the truck stood still until they caught fire and almost burned him alive. He did suffer smoke inhalation but I believe made it. It could have been the bus driver attempting to make evasive maneuvers added to the fact the car hit it as well could be why it ended up a bit farther off the road then expected.
> Switching to manual mode the doors at the fire station are opened, but they discover they can’t get their equipment out because the power lines are across the apron of the fire station.
Why couldn't the fire trucks just drive over the wires? They'd be insulated, no?
That depends entirely on the voltage in the wires. A proper high voltage line could draw an arc to the wheel and chassis if they get close enough (less than a meter can be enough). The people in the cabin should still be protected by the Faraday effect. But anything outside that cage or close by may be effected - it's almost impossible to predict which way the currents would flow.
Searching online, you find varying opinions, with little evidence. Eg most are insulated; most aren't; it's an issue of not being insulated enough to prevent arcing; in case of fault, insulation may burn away due to high current etc. I'm not sure what to believe.
Isn't an "apron" in this case an overhead structure? They might have been worried about the power lines touching the top or sides of the truck, or getting tangled and making the situation worse.
Apron in this case is more or less the driveway, I believe. From the photos (and expectations from living in Santa Clara county for several years), there is no overhead structure outside fire department buildings.
From what I can tell, the fire engines couldn't go out the front, because the wires were hanging down over their driveway and they didn't want to strike them on their way out.
Is it not possible to design power lines in such a way that voltage is cut off automatically in case they touch the ground or some other object? You can check for arcing or abnormal spikes in current. Or loss of voltage on the other end. Should be easy to do on the ends of the line, at the sub station.
I just walked past a SJ fire station with my dog yesterday, and had a nice visit with a firefighter sitting outside. I'll have to ask them about this next time I see one.
This station doesn't have a backdoor, I don't think.
I put the PDF on Drive. Rather than incur the wrath of FB's lawyers, I will manually grant access to anyone who asks (until I get tired of it), and not make it generally available.
It's mostly text, though there are some pictures at the end. Here you go:
Bruce Dembecki
August 12, 2019
San Jose Fire had an impossibly complex incident scene that will be the subject of countless Battalion Chief exams in the future...
An SUV collided with a large bendy bus, pushing the bus off the road and into a high voltage power pole, which came down on top of the bus. Power lines are down across the bus and the SUV, and the streets.
At the fire station next door there is a large bang and the power goes out... crews looking to find out what happened discovered they couldn’t open the apparatus bay doors...
Switching to manual mode the doors at the fire station are opened, but they discover they can’t get their equipment out because the power lines are across the apron of the fire station.
Manually open the back doors... the electric gate at the rear of the station is closed... plans for power loss at the station involve manually exiting through the front of the apparatus bay, time was lost as crews figured out how to open the back gate...
Meanwhile the 11 people on the bus can’t leave the bus because of the power lines... but the SUV has burst into flames, and the fire is spreading to the bus... passengers can’t stay on the bus because of the fire... they can’t get off because of the electricity...
Power remains a problem and fire crews are able to get a 1.5” line on the SUV from 30’ away... the SUV fuel tank starts dripping, the fuel ignites... the water stream from 30’ away pushes the burning fuel under the SUV... to the bus...
The bus is a diesel electric hybrid with 900V batteries on the roof, smashed from above by the power pole, being attacked from below by fire... fire crews can not fight the bus fire until a bus mechanic arrives with information on how deal with the batteries... the bus mechanic arrives, but can’t go near the bus until PG&E neutralizes the power from their lines...
Somehow, everyone was removed from the bus and there were no serious injuries.
Hours later the major traffic artery remains completely closed as PGE deals with the power... when they are done fire will look at the bus and the hazmat team will analyze the damage to the bus electrical storage systems... eventually the bus and SUV will be removed and the scene turned over to PG&E to repair the power system before the road can be reopened...
Elapsed time 4:03:00 and counting, we still can’t get at the battery systems on the bus...
It’s going to be a long afternoon - did I mention it’s 98 degrees outside?
But also, it's a Facebook post. The author's not selling subscriptions to this content. He's not charging per download. He put it in the public square himself, and in the comments he even positively comments about it being shared more widely. I would be very surprised if the author felt as strongly about this as you do.
Don’t worry. You’ve done nothing wrong. You just copied a public Facebook posting in a comment for a HN posting for said article. At no moment you violated any copyright or license.
It’s not Facebook I care about, it’s whoever wrote the post. I’m a photographer. When I find people pirating my work from social media sites I send them takedown notices. If not wanting people distributing my work makes me a corporate stooge, then so be it.
There's a difference between art and a statement of facts. What we're talking about here is mostly a statement of facts, written with the objective of informing the public instead of profit (the fire department doesn't rely on online "exposure" to fund itself).
What does the person who wrote the post lose by having a small subset of people ordinarily unable to view their original public post get to see the contents nonetheless?
There's the risk of grounding from the vehicle to earth by a disbarking passenger, as well as of ground currents within 100m or so of a high-voltage downed line.
Mitigating those conditions requires specific actions and measures. Ensuring compliance by all passengers aboard the bus is a challenge. The lesser risk might be having them remain aboard. Even the option of carrying or assisting passengers from the bus could risk grounding. Consider that passengers might be old, young, handicapped, non-English speakers, or otherwise have difficulty understanding or complying with instructions.
Question that sprung to mind, especially with the Dixie fire continue to rage- how did PG&E not know there was something seriously wrong with their equipment and shut off power remotely? That’s an honest question- the electrical system is big, complex, and often was built before I was born, but it seems like that sort of failure is something that would show up on a sensor somewhere.
