Mythbusters "Peeing On 3rd Rail" Busted

n0tWorthy writes "The Mythbusters tested the myth that you could be electrocuted by peeing on the 3rd rail. The myth was 'busted' as the stream would be broken up due to distance and there wouldn't be a continuous path for the electrical current to follow. This seems to be refuted by a Monsanto, Washington man that was found electrocuted after urinating into a ditch that had a downed power line."

Comments

Apples and Oranges

[pudge]

Third rail != power line

Re:Apples and Oranges

[Anonymous Coward]

Third rail != power line

And it's always going to be a matter of both voltage and distance that determines whether or not the current would be enough to kill you. You're protected by the resistance from the gaps in the stream, but sufficient voltage or proximity will overcome that.

I'm pretty sure they acknowledged this in a follow-up to the original episode.

Re:Apples and Oranges

[pudge]

You're protected by the resistance from the gaps in the stream, but sufficient voltage or proximity will overcome that.

Exactly. There's plenty of voltage in some currents to jump between streams of urine, but -- apparently -- not enough in a third rail of whatever train track they tested on Mythbusters.

Re:Apples and Oranges

[Sody]

Depending on the power line, it's likely the line in TFA was at least 880 volts (what the lines running along the road in a residential area carry), and likely much more. Apparently, New York's subway only runs 625 (here) and DC's Metro trains run 750 V (here). According to this, even a millimeter gap in a conducting stream (like someone's urine) would require around 3000 V to jump it. It's quite likely the pole this guy took down with his car was carrying at least 4000 V (here).

So it looks like the Mythbusters were fine, as far as they went. An electric fence or third rail is very unlikely to be able to electrocute someone through a urine stream because of the air gaps, but there are plenty of electrical transmission lines easily capable of it.

Re:Apples and Oranges

[pudge]

Awesome, thanks for the facts. It's what I suspected, but I didn't know the numbers.

Re:Apples and Oranges

[Anonymous Coward]

in one of their Myths Revisited episodes, they retested the electrocution myth and confirmed that it was possible for someone to be electrocuted by urinating on an electric fence

Re:Apples and Oranges

[Nefarious Wheel]

And it's always going to be a matter of both voltage and distance that determines whether or not the current would be enough to kill you.

Frequency too. If the frequency of the electrical current is high enough, it might just decide the outside of your skin is the easier path. You might prefer this.

Re:Apples and Oranges

[TFGeditor]

Wrong. Voltage in overhead power transmission lines (at least in the U.S.) is 7200 volts minimum per line. A single overhead line is 7200 volts, and a pair is 14,400 (180-degree phase). Even if the urine steam is broken into a series of droplets, 7200 is sufficient voltage to arc between droplets, and obviously enough current to melt you Indiana Jones-Nazi style.
     

Re:Apples and Oranges

[Anonymous Coward]

The electricity would take the easiest path. Thus it would ground itself through the urine ON THE GROUND. To think it would travel back up the (broken) stream, through the body, and out through his shoes instead belies logic. Also, a shock of several thousand volts usually will knock you back unless you are holding on to something (other than yourself) solid.

Re:Apples and Oranges

[ffreeloader]

Electric fences are high-voltage low-current circuits. As it's the current that kills you, not the voltage, when you're electrocuted, an electric fence is a low-risk proposition with respect to electrocution.

A third rail for an electric train is not a low-current application. It's both high-voltage and high-current as both are required to run electric motors, lights, etc....

As water alone can be sufficient to short out electrical circuits, and salt water even more likely to do the same, I would say I wouldn't even begin to want to experiment with pissing on a third rail to find out if it does, or doesn't, work. Also, I've worked with circuits in 440 or 600 volt range and an air gap of 1mm, not existing in a vacuum, will break down fairly easily, especially in dusty conditions.

Re:Apples and Oranges

[Anonymous Coward]

The original story was in error, the guy came into physical contact with the power line. Corrected story here:

http://thedailyworld.com/articles/2010/03/02/local_news/doc4b8d762495bc8758424321.txt

Oh yes, many have died peeing on the 3rd rail

[axeldot]

But it has nothing to do with electrocution.

Continuous path

[Rhaban]

the stream would be broken up due to distance and there wouldn't be a continuous path for the electrical current to follow.

Depends on how many beers you had.

Shocking!

[jockeys]

This news is positively electrifying!

WikiPEEdia..

[L3370]

I say we create a Wiki entry that lists out things we can and cannot pee on.

Sooooo...

[cyn1c77]

Would it feel like a really good orgasm?

You know what I am talking about: The kind that makes your toes twitch.

Spiraling Urine

[TFGeditor]

The human urethra imparts a spiral/twist to the urine stream to make it, well, stream instead of dribbling. MythBusters failed to recognize/account for this in the original tests. (Actually, they fail in fundamental things like this rather often.)