bridgebuster
Active member
According to the TV show Mythbusters, this can't happen, apparently it can
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I thought this was an urban legend.
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MikeHalloran
Mechanical
I have accidentally brushed against the NYC 3rd rail without being fried or even tickled, probably because all surfaces but the top are typically covered with rust/oil/dirt.
However providing a saline path to the interior of your body is a different matter.
Mike Halloran
Pembroke Pines, FL, USA
However providing a saline path to the interior of your body is a different matter.
Mike Halloran
Pembroke Pines, FL, USA
GregLocock
Automotive
plenty of counterexamples in the comments
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376
I seem to recal one problem with the MythBusters was they didn't allow for 'Beer Bladder' when evaluating urine flow.
Posting guidelines faq731-376 (probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484
What is Engineering anyway: faq1088-1484
ah yes... I reviewed the episode on Amazon last night. some comments:
- they didn't confirm conductivity from their "bladder" assembly to the gel in the legs - most of the bladder seemed to be of insulative material (although in the end they were able to get their target of 65mA by using more fluid and less distance, which shows there was at least some amount of conductivity.
- 65mA was their estimated maximum current based on conductivity of their urine sample(s) - so why would they set that as the minimum threshold for a successful electrocution test? Why didn't they use their stated value of 25mA-30mA for fatality?
- they didn't seem to address varying electrolyte concentrations in the urine at all
- they didn't seem to make any attempt to evaluate actual clearances between "nozzle" and rail - I'm not familiar w/NYC subway, but the BART's third rail is substantially higher than the other two rails if memory serves. Their test was w/6" rail, not elevated at all.
- They didn't make much effort to vary the pressure in the bladder nor the diameter of the stream, they only used a little stream with a little pressure to "disprove" the myth and then a big nozzle w/similar pressure to demonstrate a shock
Their experiments did seem to show the following:
- current can be carried from the rail via urine under the right conditions
- this is sensitive to distance from nozzle to track
- this is sensitive to nozzle diameter
- they didn't confirm conductivity from their "bladder" assembly to the gel in the legs - most of the bladder seemed to be of insulative material (although in the end they were able to get their target of 65mA by using more fluid and less distance, which shows there was at least some amount of conductivity.
- 65mA was their estimated maximum current based on conductivity of their urine sample(s) - so why would they set that as the minimum threshold for a successful electrocution test? Why didn't they use their stated value of 25mA-30mA for fatality?
- they didn't seem to address varying electrolyte concentrations in the urine at all
- they didn't seem to make any attempt to evaluate actual clearances between "nozzle" and rail - I'm not familiar w/NYC subway, but the BART's third rail is substantially higher than the other two rails if memory serves. Their test was w/6" rail, not elevated at all.
- They didn't make much effort to vary the pressure in the bladder nor the diameter of the stream, they only used a little stream with a little pressure to "disprove" the myth and then a big nozzle w/similar pressure to demonstrate a shock
Their experiments did seem to show the following:
- current can be carried from the rail via urine under the right conditions
- this is sensitive to distance from nozzle to track
- this is sensitive to nozzle diameter
I peed on an electric fence once and got a h#ll of a shock. I don't think diameter had much to do with it. Last time I did that. Electric fences have current limiters and will not kill anything, 3rd rails do not.
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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.
I don't think diameter had much to do with it. Last time I did that. Electric fences have current limiters and will not kill anything, 3rd rails do not.
They operate at substantially different voltages, though. The higher voltage of the elec fence makes it less sensitive to distance/diameter. A larger break in the stream can be tolerated w/enough voltage.
They operate at substantially different voltages, though. The higher voltage of the elec fence makes it less sensitive to distance/diameter. A larger break in the stream can be tolerated w/enough voltage.
dgallup,
A childhood friend did that at Scout camp. It certainly made him jump. I have no idea whether he's had kids.![[wink]](/data/assets/smilies/wink.gif "[wink] [wink]")
Over here commercially-available electric fences send a short high voltage impulse which has a limited energy level. The peak power is probably quite high but it is for such a sort duration that it is unlikely to cause permanent harm.
It has long caused me amusement that some of our open-terminal transmission substations require an electric fence for protection against the locals. You would think that 400,000V would put off most sane people from entering, and that Darwin could deal with the others if do-gooders stopped interfering with his work...
A childhood friend did that at Scout camp. It certainly made him jump. I have no idea whether he's had kids.
Over here commercially-available electric fences send a short high voltage impulse which has a limited energy level. The peak power is probably quite high but it is for such a sort duration that it is unlikely to cause permanent harm.
It has long caused me amusement that some of our open-terminal transmission substations require an electric fence for protection against the locals. You would think that 400,000V would put off most sane people from entering, and that Darwin could deal with the others if do-gooders stopped interfering with his work...
btrueblood
Mechanical
I've read a scholarly paper (having first heard about this from a urologist) that demonstrates that the breakup of a liquid stream from an elliptical orifice takes longer (has a longer characteristic wavelength) than the breakup of a circular jet (at flow rates and jet diameters similar to those exiting the human male urethra). Given the organic orifice in question here is typically elliptical, whilst the mythbusters used a piece of circular tubing, the early breakup of the mythbuster jet (which they postulated interrupted the current path at normal human height-over-3rd rail) may have been due to this phenomena.
Despite the sensationalism in the FoxsNooze headline, the man did not die of electrocution through his "whizzing apparatus", be was taking a leak off of the platform into the track area, and FELL onto the electrified rail. Nothing about this story changes the findings from the venerated Myth Busters.
"Will work for (the memory of) salami"
"Will work for (the memory of) salami"
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