Struck by lightning

[Qfwfq]

What counts most is the current density at each point in tissue, but also the gradient potential (voltage drop along the current's path). The product of course determines how rapidly heating occurs but this isn't the main problem and anyway resistivity is negligible beneath the epidermis.

 

The current OTOH is what determines the most severe physiological effects, electrolysis and neaural stimulus. The former is complicated and I know sqat about it except that burns can be severe starting from 10 or so mA; the neural stimulus is especially a hazard when it causes ventricular fibrillation. A lightning bolt is typically a rapid sequence of pulses, so it can cause such effects.

 

The voltage between you and other things while current is flowing, certainly doesn't count.

[TheBigDog]

I am glad to hear that you are not seriously injured. Have you done any checks regarding new super-powers or other new abilities since the strike? :)

 

Can you charge a battery by putting it in your ear? Does lint in the air find and stick to you? Can you name the day of the week of any date in history? Can you recite all the digits of Pi from intuition? Do you possess the power of healing hands?

 

Imagine the possibilities...

 

Bill

[modest]

What counts most is the current density at each point in tissue, but also the gradient potential (voltage drop along the current's path). The product of course determines how rapidly heating occurs but this isn't the main problem

 

Do you mean that the product of current and voltage along the path would determine tissue damage (or how quickly a resistor is heated)? I was thinking that current alone would do that. Or, I guess I should say, current per area.

 

and anyway resistivity is negligible beneath the epidermis.

 

Yes, I agree. We found in post 12 that the resistivity of blood is ~140 ohm-cm which I'd consider negligible compared to something like air.

 

The voltage between you and other things while current is flowing, certainly doesn't count.

 

Yes, I was going to add "It counts as far as being the determining factor in whether or not a person is struck", but you stipulated "while the current is flowing". So, yeah, very nice. I agree.

 

Would you think the current between my feet and head would need to be approximately equal to the current between me and the fan? And, if so, do you think using V=IR to find voltage between me and the fan (where current is estimated by tissue damage and the resistivity of air and the cross section are known) would work? Me and Jay were thinking that V=IR would be a bad approximation with high-voltage and air as post 10 seems to confirm.

 

I realize, like you say, that the voltage through the air is not a determining factor in tissue damage, but I'm mostly curious and looking for an impressive sounding number, if you know what I mean.

 

 

 

 

 

I am glad to hear that you are not seriously injured. Have you done any checks regarding new super-powers or other new abilities since the strike? :naughty:

 

Can you charge a battery by putting it in your ear? Does lint in the air find and stick to you? Can you name the day of the week of any date in history? Can you recite all the digits of Pi from intuition? Do you possess the power of healing hands?

 

I haven't noticed any new superpowers, but the old ones are still intact ;)

 

~modest

[lemit]

Ouch. We need to start a club—a paranoid group of people who think electricity is out to get them :naughty: We could hand out flyers and scare the locals. Good times ;)

 

~modest

 

James Thurber's Aunt Ida believed electricity leaked from the outlets and spread all over the house. I've never seen a picture of her, although I know some do exist. She could be a mascot for the club, or maybe we could even name the club after her.

 

I grew up afraid of lightning, partly because it seemed pretty deadly and partly because I had very sensitive hearing and felt like I was going to die when there was fairly close thunder, as there always in northern Missouri.

 

I have a question about thunder. It is apparently caused by shock waves as superheated air expands. Does an arc welder--or a Tesla coil--not produce thunder because it doesn't heat the air enough? When a particularly intense thunderstorm produces a noise similar to an arc welder, is that caused by an electrical flow insufficient to heat the air to a temperature that would create the shock waves? I hear that noise occasionally in the kind of thunderstorm that sweeps through here and causes tornadoes out on the plains. My house was previously owned by a president of the local VFW and therefore sports a flagpole. Would that work as a lightning rod and attract branches, leaders, and other electrical events not available to people who don't have their very own flagpoles?

 

Thanks, and a special hello to all other members of the Ida Fisher Club.

 

--lemit

[Boerseun]

Sheeeesh, mate - glad you're alive!

 

If you were a religious type, then it was probably God who smacked you across the ear because you didn't pay him enough last Sunday.

 

Be that as it may, if the current was strong enough to break down the resistance between your head and the ceiling fan, then it sure as hell was strong enough to break down the resistance of the soles of your shoes. That current must have gone somewhere. Did you notice anything funny on your feet? Or on your bum - it could just as well have passed through your chair?

 

The other possibility is that you were static, and the current actually came from you and snapped off, dissapating into the air. Are there any marks on the ceiling fan? This would explain why it sparked your ear, which is pretty thin and pointy (not mr. Spock pointy, but you catch my drift)

 

The closest I've ever got to this was in a thunderstorm, where all my extremities started getting needles and pins - fingers, ears and the tip of my nose, and my scalp was all a-crawling. Nothing zapped or sparked, but I guess it wasn't far off. Did you feel any needles and pins before the zap?

[Turtle]

first, glad to hear you well enough to report your experience Sparky, erhm...i mean modest. :naughty: ;)

 

 

... My house was previously owned by a president of the local VFW and therefore sports a flagpole. Would that work as a lightning rod and attract branches, leaders, and other electrical events not available to people who don't have their very own flagpoles?

 

Thanks, and a special hello to all other members of the Ida Fisher Club.

 

--lemit

 

the flagpole may or may not work well as a lightning rod. if it is not buried deep enough & in "good" contact with earth of "good" conductivity, then it may not attract lightning more readily than other contacts.

 

this whole article is good, but one part got me thinking that perhaps the fan housing is not properly grounded & so caused a side-flash that then found Sparky modestly attractive. :eek: :hyper:

 

Lightning rod - Wikipedia, the free encyclopedia

...Additional precautions must be taken to prevent side-flashes between conductive objects on or in the structure and the lightning protection system. The surge of lightning current through a lightning protection conductor will create a voltage difference between it and any conductive objects that are near it. This voltage difference can be large enough to cause a dangerous side-flash (spark) between the two that can cause significant damage, especially on structures housing flammable or explosive materials. The most effective way to prevent this potential damage is to ensure the electrical continuity between the lightning protection system and any objects susceptible to a side-flash. Effective bonding will allow the voltage potential of the two objects to rise and fall in tandem, thereby eliminating any risk of a side-flash.[12] ...

 

then there is this fella: >>

US Park Ranger Roy C. Sullivan from Virginia holds the record for the person most times struck by lightning - and living to tell the tale. Between 1942 and 1983, Roy has the dubious distinction of being struck by lightning seven times. He was known as the Human Lightning Rod

Struck by lightning record seven times: Weird News, Strange But True Stories, Odd Facts, Bizarre

[lemit]

Thanks, Turtle. I'm sure you're right about the flagpole. Thanks also for explaining something I'd been trying to remember, the side-flashes. I think lightning in a house is somewhat like a squirrel in a house, that is, unpredictable, all over the place, and generally pretty destructive. Pinning down the path of a lightning strike, particularly with all the wiring and electronics, is a pretty difficult job. There are so many attractive conduits that it's like finding a needle . . . .

 

Well, that analogy might not work. A grounded needle might be pretty easy to find after a lightning strike on a haystack: just look for the origin of the fire. (Maybe all those haystacks that burned after thunderstorms when I was growing up had needles in them. Presumably it's a pretty common occurrence to have become such a cliche. I'm sure veterinarians get a lot of camels with broken backs. I know that when I was about 11, I tried to be awake every morning just before dawn to see if it really was a lot darker.)

 

But regardless of where the lightning came from, if it burned the skin, it may well have done some other damage. I don't know if your doctor's response, a good laugh, is sufficient. I hope so.

 

--lemit, proud Ida Fisher Club member

[Qfwfq]

In order to be good, a lightning rod should have a sharp point at the top and must be well earthed. The earthing, however, must be good as far goes withstanding the current, which in some cases may be some kA's. The earthing's resistance is important only in these cases, since even a tenth of an ohm will give a significant voltage for anyone touching the earth line.

 

The purpose of the sharp point is to more effectively ionize air, making it the favoured path. In days when people were less jumpy about mildly radioactive devices, some lightning rods were made exploiting the ionizing effects of nuclear radiation; this added to the point effect by which the electric field itself more easily causes ionization.

 

Do you mean that the product of current and voltage along the path would determine tissue damage (or how quickly a resistor is heated)? I was thinking that current alone would do that. Or, I guess I should say, current per area.

Well, I was a bit muddled in my hurry; I could have said that "voltage along the path" is the electric field (E). Current per area is what I called current density. So their product gives density of total absorbed power but the effect of electrolysis is worrisome far before the thermal energy is.

 

Would you think the current between my feet and head would need to be approximately equal to the current between me and the fan? And, if so, do you think using V=IR to find voltage between me and the fan (where current is estimated by tissue damage and the resistivity of air and the cross section are known) would work? Me and Jay were thinking that V=IR would be a bad approximation with high-voltage and air as post 10 seems to confirm.

Charge is conserved, current that doesn't follow one branch follows another. The air becomes conductive when its dielectric rigidity has been passed and ionization starts. This is what the lightning rod should favour. The resistivity gets far lower when that has occured. Ohm's law isn't all that helpful (at least, not without plenty of assumptions).

 

I realize, like you say, that the voltage through the air is not a determining factor in tissue damage, but I'm mostly curious and looking for an impressive sounding number, if you know what I mean.

Like, when you won a few hundred from a lottery draw, someome else won several million! :naughty:

[pamela]

Ouch. We need to start a club—a paranoid group of people who think electricity is out to get them We could hand out flyers and scare the locals. Good times

the minute you were struck you became a full fledged card carrying member

just you wait modest, since that day way back in the eighties, i have become the not only the receptor at times but a conduit as well. I cannot get in and out of my truck wiithout getting shocked.I cannot change an outlet cover without starting a fire up the wall.I cannot successfully remove a heavy wired box from the circuit, even tho the power has been shut off for over one week without getting an overwhelming zap.i am the human terror on carpet in the winter sending screeching kids running.And as far as lightening goes, it all gets unplugged.Surge protectors are to no avail.The damn bastard went after my comp, the printer, the playstation, completely destroyed the protector and started a fire in the wall. A week later it went after the transformer and set my yard on fire. Am i scared? heck no, i just chalk it up to a magnetic personality;)

[modest]

The air becomes conductive when its dielectric rigidity has been passed and ionization starts.

 

Thank you Q! The term "dielectric breakdown" has been on the tip of my tongue all through this thread. Easily now googled, the dielectric strength of air is 3 x 10⁶ V/m. As you indicate, this changes some with the geometry of the electrodes, and the pressure and humidity of air, but is a superb approximation me thinks. So, the OP can be answered (for whatever that's worth):

The distance between me and the lowest point of the ceiling fan above me at the time was just over a meter... what was the minimum voltage...

The minimum voltage needed to make that jump would be approximately 3 million volts.

 

Like, when you won a few hundred from a lottery draw, someome else won several million! ;)

 

I won the 3 million volt lottery* :hyper:

 

~modest

 

*1,666 volts of it anyway :naughty:

[freeztar]

*1,666 volts of it anyway :naughty:

 

So, assuming 70mA, that would be 117 watts (max).

 

That's quite a jolt, but seems to make sense, intuitively.

[modest]

James Thurber's Aunt Ida believed electricity leaked from the outlets and spread all over the house. I've never seen a picture of her, although I know some do exist. She could be a mascot for the club, or maybe we could even name the club after her.

 

Perfect. Now all we need are some bubblewrap jumpsuits and a 300 page manifesto addressing the evils of electricity. :naughty::eek2:;)

 

 

 

 

Sheeeesh, mate - glad you're alive!

 

If you were a religious type, then it was probably God who smacked you across the ear because you didn't pay him enough last Sunday.

 

Actually, it's kind of funny, and I'm not kidding about this. I literally got struck by lightning a few minutes after making this post:

 

Re: Does this physical "evidence" make you believe in God?

 

Hummmm....

 

Then again, when it happened I was PMing Pam about Michael Mooney. So, I could blame either of them. :hihi:

 

Did you notice anything funny on your feet? Or on your bum - it could just as well have passed through your chair?

 

Yes, my head and foot were both tingling after I regained my senses. I was barefooted on hardwood flooring, so I'm pretty sure even though my foot isn't visibly burned that was the exit point.

 

The closest I've ever got to this was in a thunderstorm, where all my extremities started getting needles and pins - fingers, ears and the tip of my nose, and my scalp was all a-crawling. Nothing zapped or sparked, but I guess it wasn't far off. Did you feel any needles and pins before the zap?

 

No, I've heard that happens, but none that I felt—it was most unexpected.

 

 

 

 

 

 

first, glad to hear you well enough to report your experience Sparky, erhm...i mean modest. :hyper: :hyper:

 

:) Thank you.

 

this whole article is good, but one part got me thinking that perhaps the fan housing is not properly grounded & so caused a side-flash that then found Sparky modestly attractive. :eek: :hyper:

 

That's kind of what I was thinking... along the lines of a side-flash. Mostly I'm sure the walls, pipes, and the structure of the house carried the current.

 

I really don't have anything that would work as a lightning rod. My first thought was the sewer roof vent, but that might be plastic—not sure. There may be nothing conductive and grounded going from my ceiling up through the attic to the roof. :shrug:

 

 

 

 

 

 

But regardless of where the lightning came from, if it burned the skin, it may well have done some other damage. I don't know if your doctor's response, a good laugh, is sufficient. I hope so.

 

--lemit, proud Ida Fisher Club member

 

I probably made the Dr. sound less concerned than she was. I'm thinking about going to a dermatologist though—if for no other reason than it's starting to look like it might leave a scar.

 

 

 

 

 

the minute you were struck you became a full fledged card carrying member

just you wait modest, since that day way back in the eighties, i have become the not only the receptor at times but a conduit as well. I cannot get in and out of my truck wiithout getting shocked.I cannot change an outlet cover without starting a fire up the wall.I cannot successfully remove a heavy wired box from the circuit, even tho the power has been shut off for over one week without getting an overwhelming zap.i am the human terror on carpet in the winter sending screeching kids running.And as far as lightening goes, it all gets unplugged.Surge protectors are to no avail.The damn bastard went after my comp, the printer, the playstation, completely destroyed the protector and started a fire in the wall. A week later it went after the transformer and set my yard on fire. Am i scared? heck no, i just chalk it up to a magnetic personality;)

 

Alright :D We've got 3 card-carrying members of the IFC now.

 

My Faraday cage to work and sleep in is almost finished. That'll show these evil electric fields who's in charge. :eek:

 

~modest

[modest]

So, assuming 70mA, that would be 117 watts (max).

 

That's quite a jolt, but seems to make sense, intuitively.

 

Yeah, they say power = voltage x current, so that would be 117 watts :naughty:

[pamela]

Actually, it's kind of funny, and I'm not kidding about this. I literally got struck by lightning a few minutes after making this post:

 

Re: Does this physical "evidence" make you believe in God?

Hummmm....

 

Then again, when it happened I was PMing Pam about Michael Mooney. So, I could blame either of them.

hahahahahah!

transpersonal electricity?

ahhh yes, i see it all quite clearly now.

I am the hot wire

modest you are the neutral

and michael i guess you're grounded:D

[freeztar]

hahahahahah!

transpersonal electricity?

ahhh yes, i see it all quite clearly now.

I am the hot wire

modest you are the neutral

and michael i guess you're grounded:D

 

 

I needed a laugh, thanks!

[Qfwfq]

:lol:

 

Anyway, as you can see, 117 watts for a fraction of a sec would be schmuck if it were just heat alone. It's the chemical changes that cause the damage and of course neural stimulation stuns and causes wild contractions.

[Turtle]

how ya feelin' now sparky? :cup: any new quantifiable effects that you can relate to physics?