5 ms·
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
by jcims 5y ago
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.
- dehrmann 5y agoIs there a right technique for hopping (literally) out of bus like that?
- 14 5y agoWe 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.
- admax88q 5y agoShuffling 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.
- Thorrez 5y agoWhere 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?
- TeMPOraL 5y agoIs 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.
- msh 5y agoI 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.
- dharmab 5y agoIn the US, most power lines are overhead. Downed power lines are common. Well over 100,000 incidents per year: https://www.nfpa.org/-/media/Files/News-and-Research/Fire-statistics-and-reports/Electrical/osNonFireElectricalIncidents2020.ashx https://www.nfpa.org/-/media/Files/News-and-Research/Fire-st...
- 14 5y agoI’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.
- dharmab 5y agoIn 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.
- jhgb 5y ago> Given enough voltage, electricity can cross the gap to the ground Doesn't smoke make air more conductive?
- dharmab 5y agoYes but if the smoke is that thick you're about to pass out from smoke inhalation anyway
- jhgb 5y agoI'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 https://www.osti.gov/servlets/purl/3313 .
- bagels 5y agoThis is the recommended procedure for exiting some stricken Formula 1 cars due to their hybrid powertrains.
- dharmab 5y agoMany race series will require internal and external buttons to cut the battery as well: https://youtu.be/qM_iXuuwC9M?t=687 https://youtu.be/qM_iXuuwC9M?t=687
- bentcorner 5y agoI've read that if you must, to hop with your feet together if you are near a downed line.
- tejtm 5y agothen shuffle without lifting your feet keeping them tight together
- edoceo 5y agoCould thick rubber mats or blankets help? (or other non-conductive material) like an escape slide?
- ithkuil 5y agoWould running work? (By running I mean literally jumping from one foot to the other).
- bpoyner 5y agoThis video describes some of the hazards and how to avoid them. https://www.youtube.com/watch?v=fLVzvMTgGDY&t=170s https://www.youtube.com/watch?v=fLVzvMTgGDY&t=170s
- gorgoiler 5y agoWhat is potential gradient and how does it ruin your day?
- jcims 5y agoIn 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).
- c_o_n_v_e_x 5y agoAssume your blessed with perfect balance and athletic ability... Electrically speaking, wouldn't you want to hop on one foot?
- Sharlin 5y agoHopping with your feet together works just as well and is much easier.
- tomp 5y agoHow about running? (The definition of "running" vs "racewalking" is that at some point during each "step" of "running", both feet leave the ground.)
- mschuster91 5y agoBad 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.