March 20, 2014

Why little David wasn't shocked when he peed on an electrical outlet.

In yesterday's post about toilets, the commenter David-2 recounts a story of getting up in the middle of the night to pee when he was a little boy and not only missing the toilet, but hitting "a very badly placed electrical socket."
I still remember the fireworks show! I wasn't shocked (electrically, I mean) or hurt ... just damn surprised!
A nice thing about blogging one commenter's lifelong mystery is solved by other commenters. SJ takes the first shot, but kind of misses:
And I spent 10 minutes trying to figure out why you didn't receive an electric shock... The path-of-least-resistance for electricity was from the +110V AC wire to the neutral wire, and not through the urine to you. Now, I'm no longer surprised that you weren't shocked.
That brought correction from sojerofgod:
Actually, that is not why he wasn't shocked. Water does not actually flow in a stream. The surface tension of the liquid is such that it actually forms discrete droplets that are invisible to the eye due to the "analog" nature of vision. (See: Visual persistence.) Only if the voltage had been high enough to arc from droplet to droplet would the electricity have found him. -or if the distance was very short, which would kind of blur the line between "accidentally" and "deliberately" if the boy chose the latter, well, lets just say its a weird way to light up your life...

28 comments:

Seven Years of College Down the Drain said...

Were any of the rest of us shocked when little David peed on the electrical outlet?

Xmas said...

A strobe light is fantastic for showing the droplets that make up a stream of water. The Boston Museum of Science used to have a display that showed that.

I'm not sure if it's there anymore. The chance of causing seizures with strobe lights is a little too high for today's society.

garage mahal said...

I've heard that if you piss on an electric fence the current does travel back to the source. Ow.

Ralph Hyatt said...

http://www.youtube.com/watch?v=tU1UKn7iXv8

Bob Boyd said...

"There are three kinds of men. The one that learns by reading. The few who learn by observation. The rest of them have to pee on the electric fence for themselves.” - supposedly Will Rogers

hawkeyedjb said...

It may also depend on the electrical strength of the target. For some examples, just Google "man urinates on third rail."

betamax3000 said...

Comedy Stage Open Mic Night Comic says:

It's interesting: there are things that didn't make much sense when you were a kid, but make sense once you're older. Mom and Dad having sex, that's one right there (laughter). Never should've opened that door, never should've opened it: (laughter) for years I believed my naked Dad thought Mom was a wheelbarrow (laughter): he kept pushing her from behind, pushing and pushing, but she wasn't going anywhere (laughter). I mean -- Dad -- Mom is on her knees, she doesn't have wheels (laughter)...

One thing that still doesn't make sense to me, though: why my Uncle Harold kept jars of urine under the bed. (laughter) Still don't get that one. I can understand needing to 'go' and being so drunk you don't want to get out of bed, and there's a beer bottle there, so...(laughter) But I would think you'd flush it in the morning. That would be the right thing to do, right? But Uncle Harold: there were dozens of these jars, under the bed, dozens. I'm assuming they all had urine -- I didn't get around to inspecting those in the back (laughter). Then again, maybe I missed out: maybe, in the back, he had a jar with thousands of dollars in it -- figuring, hell, no burglar would go through ALL those bottles of urine expecting to find anything of value (laughter)...

So -- as a child -- after much thought, I figured the only reasonable explanation: the monsters under the bed kept their urine in jars (laughter). Sounds like what monsters might do, collect their precious Monster Urine for their evil deeds (laughter)...

Anyway -- years later, after Uncle Harold died -- I was going through our garage and lo-and-behold, I found one of Uncle Harold's jars of piss at the back of a shelf: I assume Mom got it in the will (laughter). Maybe it makes sense to my Mom, but I'm afraid to ask -- maybe it'll make sense when I'm in my sixties (laughter)... Thank you, you've been great...

PB Reader said...

I don't believe sojerofgod is correct. Water most definitely flows in a stream and is indistinguishable from a standing body or a river (which most definitely flows) in this regard. Urination is also mostly a continuous stream.

The reason the person isn't shocked IS because of the path of least electrical resistance. Even if you stand in your bare feet on a wood or tile floor, the path to ground is shortest and least resistant within the socket itself, wood and ceramics being pretty darn good insulators.

The reason for the sparking in and around the wall socket was because of the current jumping from puddle of droplet to droplet, particularly as the water boils off from current flow through the water and the heat generated from the water's resistance (just as your body would heat up if significant current would flow through it.

jimbino said...

When we were boys on the farm, before we discovered sex, we'd pee on the electric fence and we sure got a tingle--similar to the tingle we got when we held a green leaf to the charged wire. Of course, the voltage of the electric fence many times that of an electrical outlet, meaning that conduction is possible through pee-vapor. Even normal wire insulation will "conduct" above a few thousand volts, which is why high-tension lines aren't insulated at all.

DKWalser said...

I've heard that if you piss on an electric fence the current does travel back to the source. Ow.

My 8 year-old self can attest both to the fact that its possible and that it hurts. Several decades later, I've still not forgiven, nor gotten even, with the cousin who persuaded me peeing on an electric fence was good luck.

DKWalser said...

I've heard that if you piss on an electric fence the current does travel back to the source. Ow.

My 8 year-old self can attest both to the fact that its possible and that it hurts. Several decades later, I've still not forgiven, nor gotten even, with the cousin who persuaded me peeing on an electric fence was good luck.

SJ said...

@Ann,

I didn't know you had a penchant for circuits and electronics.

@jimbino,

I've heard a similar story from my own Uncle.

I'm not sure whether electric fences are typically high voltage or low voltage.
I think the real question is whether it is DC or AC.

@PB Reader: I kind of suspect you're right, but I'm not sure I really want to do any field tests in the name of science.

Magson said...

Mythbusters did a segment on peeing on an electric train rail a few years back.

https://www.youtube.com/watch?v=pDY-0ijiOEQ

dbp said...

Only one of the slots in a plug is hot, the other is a ground. The third, round one is an earth ground.

If the boy had managed to only pee on the hot slot (with such accuracy, he should have hit the bowl) then he could have been shocked. Instead, he splashed onto both slots and the urine provided a conductor between the hot and the ground.

David said...

PB Reader is correct. If the receptacle is grounded then it is not possible for your "stream" and feet on tile floor to draw significant current to ground.

Also, the stream may start out continuous but it does eventually break into droplets. I presume the electric fence works because one is standing relatively close to it.

Peter said...

"I'm not sure whether electric fences are typically high voltage or low voltage.
I think the real question is whether it is DC or AC."


It's high voltage DC. And it doesn't last long, just long enough (it's not there to kill the farm animal, just to persuade it to avoid the fence).

The old fencers (the part that charges the fence) just charged a capacitor- if you discharged it, it could take a few seconds to charge it back up. Today's fencers mostly provide a continuous stream of brief DC high-voltage pulses.

eric said...

soferofgod is incorrect.

It's true that there is no continuous stream, it's drop following drop, but there is plenty there to make that jump and shock little David.

As a child, we did this a lot with a very low voltage electric fence around our yard. This wire had no ground, so if you touched it, YOUCH! And we touched it with all sorts of stuff. We used a rubber hose (Yes, the typical garden hose would send quite a jolt back up at you), a wooden stick, and even urine. We'd dare each other and pay the price. We'd even hold on to one another and learn a bit of a lesson, the guy at the back of the chain would get the worst shock. I still don't know why that is.

David said...

A little boy? Ha.

11 brewskis and 2 brandies for the chase at age 23 is more like it.

Do not trust people named David.

rhhardin said...

Electric fences aren't low voltage.

The battery voltage is low but it's converted to very high voltage pulses albeit with low current.

David-2 said...

David @ 12:40PM:

Why pee on my Althouse post? You've got to be the most cynical David I've ever met. (And I've met quite a few, since I was born in the 50s.)

jimbino said...

Interesting to me is how much we've managed to dumb down our current generation of kids.

In my day, we knew lots of ham radio operators and munitions experts (returned from WWII).

We also had chemistry sets (see Oliver Sachs books) with which we could make explosives. Of course, we did.

Today's kids don't know how to build a crystal radio or a bicycle, much less an airplane using bicycle technology.

They can't make gunpowder or other simple explosives. They can't pee on an electric fence, enjoy the increasing voltage of a Tesla coil or make a strobe light.

We kids knew how to hold our breath until passing out and enjoying a seizure. We knew how to launch CO2 cartridges across the college campus or through gypsum board walls.

Robert Goddard, praised by von Braun for teaching him rocket science, could not exist in the USSA today. His phone would be tapped by NSA and he would be arrested and imprisoned.

No country for young physicists!

Life now is so safe for Amerikan kids that rocket-science (not to mention pharmaceutical, medical device and stem-cell research) will have to take place overseas, especially now that Obamacare and drug screening have made work in the USSA so distasteful for a rocket scientist.

I am a rocket-scientist who can testify personally to all that.

Hazy Dave said...

SJ is right. And don't underestimate the firehose capacity of a young boy's bladder. Discrete droplets, indeed.

Kirk Parker said...

DBP,

"Only one of the slots in a plug is hot, the other is a NEUTRAL. The third, round one is an earth ground."

FIFY.

jimbino said...

The definitive study of the breakup of a column of pee was performed by Lord Rayleigh around 1895. He showed that a column of water tends to break up into spherules under the force of surface tension of the water. He showed that the size of the spherules was related to the velocity of the stream and the diameter of the nozzle (through Bessel functions) and that a stream first forms a column of spherules joined by finer columns, and that the finer column, having a different diameter, would break up into ever smaller spherules and ever finer columns joining them. Ultimately, the entire column would consist of independent spherules of varying sizes.

Under action of a forcing frequency (vibrator) at the discharge nozzle, a column of 2, 3 or more streams would be formed by collisions between the larger and smaller spherules, leading to a fantastic show that can be appreciated only under a strobe light,which Rayleigh in his day approximated by a spark coil similar to that used in a Tesla coil.

It is interesting that a man could use a vibrator when peeing to control the spray, enhancing both his experience and the bathroom experience of women. It should be noted, however, that a stream of pee hitting porcelain or water results in serious splashing that Lord Rayleigh didn't weigh in on.

fizzymagic said...

garage mahal said...

I've heard that if you piss on an electric fence the current does travel back to the source. Ow.


Garage maintains his record of being 100% wrong in everything he says. Impressive.

sojerofgod said...

Well I am so thrilled that I got an honorable mention on this blog! even if the subject is (ahem) a little less than could be desired. I suppose I should take the bow and shut up about that...

sojerofgod said...

Now as to some of the doubters and naysayers here; You are all wrong and I am right.
So if you agree with me we can all get along well.

No seriously, this subject is a lot more complicated than they suppose and I didn't want to go into all the variables but, well here is a brief overview:

You can lick your finger and stick it into an electrical outlet and not get shocked. Assuming a few things of course: First and mostly, the question of whether you get shocked is one of grounding if you ain't grounded you don't get the juice. you can actually hold on to a live wire with both hands and not get shocked -ever see a bird on a wire? they aren't vaporized instantly are they? In our friend's case peeing on a wall outlet did not shock him. Like I said, if the distance had been shorter then the chances of electrocution would have been much greater. That is not the only variable though. how well he was grounded would have a lot to do with what happened. was he barefoot? wearing bunny slippers or feetsies? What was the floor composition? a slab will conduct where a raised wood floor generally will not. How bad did he have to go? Things like um, "Pump pressure" and "pipe diameter" have a great deal of bearing on the stream characteristics.
I really don't want to get into formulas and math. I hate math. but I worked on electrical equipment for 20 years and I do know about getting shocked. Repeatedly. Comes with the territory.

sojerofgod said...

dbp said...
Only one of the slots in a plug is hot, the other is a ground. The third, round one is an earth ground.

You do know that both grounds end up being terminated to the same place? The ground bus inside your circuit breaker box connects both the wires to a 6-8' metal rod driven into the earth outside the house, usually right below the electric meter. Hence the term "Ground"