Electrical Shock Log Book

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Tubetec said:
I once went on a college trip to Russia , the group stayed on the top floor of a 25 storey hotel in Moskow for a few nights .
Anytime we tried to press the lift call button a spark would jump across the gap the instant before touching the switch, on a few ocassions a casual brush off a person closeby and click, more sparks .Very weird ,not something Ive experienced before or since ,I wonder were the lifts acting as a van der graph generators ,sparks were a few mm in lenght ,so  we must have been charged upto killovolts ,Id be interested if anyone has any possible explanations .
That sounds like static build up from shuffling feet on carpeting...  actually pretty common in cold dry climates. High humidity generally reduces the static build up.

JR

 
JohnRoberts said:
I felt a lightning shock through my feet while standing outside in a rainstorm after several beers challenging Thor...  Oops...  :eek: haven't done that again.  I now respect lightning.  8)  Getting hit by lightning is lower probability than tornadoes (?) but the only reason lightning doesn't strike the same spot twice is because the spot is usually vaporized after the first hit.  Tornadoes will return to the scene over and over.

Lightning is high enough voltage that it can be pretty unpredictable and there are two strokes, an upstroke with relatively modest current that ionizes the path, and then a heavy current downstroke that does the actual damage (ionized paths are conductive)...  If the ionized upstrike path gets disturbed the downstroke seems to possess momentum and finds a new path. Logical if the path is broken it finds a new path based on high relative voltage potentials.

In general avoid lightning...  I encountered my share when jogging in sudden rain storms and tried to hang out near road side power poles and other grounded protection. Properly done the grounded power poles will diffuse the static potential, and prevent the upstrike to not draw a direct down strike. 

JR
My Greek grandfather was caught in a storm. He went under a tree to get some shelter. He was struck by lightning and the "story" goes he was found naked, his clothes blown off and stuffed into the rough rock walls surrounding the trail he was on. He lived, but had the lightening gone through his left side it would have gone through his heart and killed him instantly. As it was, he had terrible foot problems the rest of his life due to damage of the lightning (exiting?).

That was an interesting story JR thanks.

I also have read of people getting hit more than once; in the Guiness Book it's said a man was struck 7 times. Not sure I buy it, nor why that would be the case.

Maybe he just had a magnetic personality?  ;D
 
Tubetec said:
I once went on a college trip to Russia , the group stayed on the top floor of a 25 storey hotel in Moskow for a few nights .
Anytime we tried to press the lift call button a spark would jump across the gap the instant before touching the switch, on a few ocassions a casual brush off a person closeby and click, more sparks .Very weird ,not something Ive experienced before or since ,I wonder were the lifts acting as a van der graph generators ,sparks were a few mm in lenght ,so  we must have been charged upto killovolts ,Id be interested if anyone has any possible explanations .
Happens here all the time. It's annoying when I go to pet my cat and I inadvertently shock her first! She doesn't like that!
 
Phrazemaster said:
My Greek grandfather was caught in a storm. He went under a tree to get some shelter. He was struck by lightning and the "story" goes he was found naked, his clothes blown off and stuffed into the rough rock walls surrounding the trail he was on. He lived, but had the lightening gone through his left side it would have gone through his heart and killed him instantly. As it was, he had terrible foot problems the rest of his life due to damage of the lightning (exiting?).
Yes hiding under a tree is a classic way to get killed by lightning. Lightning likes to hit trees.

My strategy to hug the side of the road with power poles because they generally don't get hit by lightning (I expect they use a variant on lightning rods to dissipate local charge and prevent direct strikes. )
That was an interesting story JR thanks.

I also have read of people getting hit more than once; in the Guiness Book it's said a man was struck 7 times. Not sure I buy it, nor why that would be the case.
apparently to be hit multiple times, one would have to be where lightning strikes, so likely not an office worker....  I never understood playing golf in the rain... that seems like asking for it.
Maybe he just had a magnetic personality?  ;D
He surely had a story to tell.

JR
 
JohnRoberts said:
That sounds like static build up from shuffling feet on carpeting...  actually pretty common in cold dry climates. High humidity generally reduces the static build up.

You ain't kiddin'. Right now here it is 30F outside, and air at that temp does not hold much moisture. When it leaks inside and gets heated to 75F, the relative humidity is very low. For some reason, the dehumidifier is on and set to 40% RH, but it is just setting there feeling useless, with nothing at all to do. I should go unplug it until spring.

I'm walking around the house getting zapped by everything I touch, probably not a good day to sort out older cmos chips.

One solution, years ago I put a "touch me first" resistor near one of the power switches on my stereo to drain off the charge.

Gene

 

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Gene Pink said:
You ain't kiddin'. Right now here it is 30F outside, and air at that temp does not hold much moisture. When it leaks inside and gets heated to 75F, the relative humidity is very low. For some reason, the dehumidifier is on and set to 40% RH, but it is just setting there feeling useless, with nothing at all to do. I should go unplug it until spring.

I'm walking around the house getting zapped by everything I touch, probably not a good day to sort out older cmos chips.

One solution, years ago I put a "touch me first" resistor near one of the power switches on my stereo to drain off the charge.

Gene
Yup, my dehumidifier(s) are off right now and humidity still only 30%, but that is rare in MS, so I expect more normal weather to return in about a week.... but cold and dry for next few more days. 

I haven't had any static issues recently but back when I lived  el norte (in CT), I had a several megohm resistor attached to the grounded screw on my office light switch plate so I could discharge myself painlessly without the light show, and drama.

We also had an old shop vacuum that thought it was a portable van de graaff generator, so cleaning my office carpets required a resistor limited discharge or pain would result.  :eek:

JR
 
Its always so damp and humid here in Ireland static doesnt get a chance to build up ,
would be a cool party trick for someone with a gas cooker to be able to light the flame with a spark from the finger tip ,it would appear like sorcery to the non technical people at your dinner party .
 
One of my mentors at the first studio where I worked told me about an engineer he knew who was once struck by lightning.  Apparently this fellow could move the touch-sensitive automated faders on the console and the computer would not recognize the moves!
 
sept 8th 2018

probing Epiphone amp B+ with clip leads where the black insulator slid down the cable, too lazy to replace it,

500 volts across right hand, this is the first shock where i actually saw a small puff of smoke coming off my hand,



 
Anything over 300V deserves respect! ::)

If respect goes against the grain, then surgical gloves and a rubber fatigue mat might make you last a bit longer :-\

DaveP
 
Interning at an electronics shop back in the 90's, was at the shop alone one day, thought i turned off the variac that was supplying power to the peavey amp i was tasked to fix... nope... grabbed the ac line and froze.  110 - 120 AC from the wall.  My knees gave out eventually and i fell disconnecting me from the line.  I either passed out or fell asleep where i landed below the bench for a bit.  Had a horrible headache for about a day and had that weird metal smell and taste like when you get a nosebleed. My  fingers and forearm were very stiff for quite a few days after.  I think my upper forearm was resting on the chassis and the current was going up my arm to about the elbow where it was touching. 

Building an LA2A and forgot to discharge the caps... took B+ which sparked, and make a loud pop scaring the crap out of my wife and me as it kind of shot my hand back (or maybe i just pulled it back quick).  That was around 275 or more DC...  that happened twice a few years apart.  Both times fingers had some brown marks.  Fun times.

Recently building a tube reverb unit, accidentally missed a ground and wound up sending the B+ for that (around 200 something VDC) to the cable ground coming from the unit.  Went to unplug the thing and got a nasty buzz.
 
If you are getting zapped after walking across carpets, try damping them down slightly with soapy water splashes.  I have no idea why this works, but it was standard practise when I worked for a computer company in the UK and seemed to work fine (along with personal ESD bracelets). 

You could also try holding a small piece of metal in you hand when you touch other things so that the discharge flows through it and sparks off it rather than your finger tips.

Cheers

Mike
 
> I have no idea why this works

Maybe if the UK were not all-wet 99.44% of the time, you'd have an idea.

Actually I do not know the physics (probably conductance), but damp stuff won't hold a charge like dry stuff does.

Instead of "splash" we fill a cleaner spray bottle with water and a pinch of soap. Even better: No-Cling additive as sold for laundry clothes dryers, so your dress does not cling to your pantyhose. The NoCling is hydrophilic, it attracts water and holds it in the carpet.

Used to be, at work, all the PCs would lock-up when heat came on in autumn. Specifically the worker would come back to the PC and it would be "locked". Worst-case, a static shock was reported, usually not. So part of my job was spraying the carpets and chairs a couple times every year.
 
That was THE standard method when I was a small boy.

It was incorporated in a Sea Hunt episode.

When I was an older boy suddenly it was all Mouth To Mouth. They said flapping the arms and chest did little.

When we all got AIDS it got complicated. Unless you are trained and carry tubes etc, you don't share breath with strangers.

Last year we went for CPR training. Pump the chest with a disco beat. You won't get AIDS etc this way. (It was brutal on my bad back.) It does save some lives. I strongly suggest you sign up for a class. They give you a dummy with real-feel chest springs, they play Staying Alive, they walk around and guide you. We were just two old folks in a room full of home nurses and a few emergency service workers, who need the certificate for their jobs.

 
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