Electricity Kills

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Doing my continuing ed requirements today and they had this nifty chart I wanted to share with you. A tiny amount of electricity will kill you. Most people don't realize how little it takes. Please note those measurements are in miliamps. Thats three places past the decimal. Household breakers are usually 15 amps or larger.
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[Robinson]

I wonder how an electric fence rates -- I've touched those a few times. I was shocked by 110 once while standing on a stool and it knocked me right on my ass.

[JohnO]

Technically current (amperage) kills. Also the path it takes. You can take a hit from a big source if it does not follow a destructive path. Across the heart is certain death. In one finger and out same or another on the same hand can hurt or burn but likely will not kill you. However if you ground yourself by touching lets say a grounded copper pipe with your left hand and your right hand comes into contact with a hot source you are fairly certain to establish an across the heart path. I say fairly certain because electricity can be rather fickle. There may exist a path of least resistance outside of the obvious.

[Drang]

Also, 110=volts, not amps.

What is the difference between amperage and voltage (https://www.answers.com/Q/What_is_the_difference_between_amperage_and_voltag e)

[Clusterfrack]

Worst shock I ever had was from a 12 VDC power supply for a 2hp servomotor. It kicked my ass and left me on the ground. Way worse than any of the 120 VAC shocks I've experienced.

[Cypher]

I'm almost positive I got hit by 480 volts while trying to turn off a Strippit turret press. I grabbed the cabinet door and reached for the breaker and missed the switch and touched a piece of metal on the breaker. I felt the electricity going through me but I couldn't let go of the machine. I have no idea how I broke loose but I never turned that machine off like that again

[ranger]

We are active in boating. Many people underestimate the dangers of stray current in the water around boats in the marina.

[Welder]

Worst shock I ever had was from a 12 VDC power supply for a 2hp servomotor. It kicked my ass and left me on the ground. Way worse than any of the 120 VAC shocks I've experienced.

That's interesting. Despite the movie and TV shows where car batteries and jumper cables are used to inflict torture, I've never heard of anyone actually being shocked by 12V. I can grab hold of both posts of a car or heavy equipment battery and hold on all day without feeling a thing, and some of those are rated in the 1200 or more CCA range. I would guess that many engine starting motors are in the same hp / amperage draw range as the servomotor you're describing.

Were there odd conditions on that job?

[blues]

Worst shock I remember getting was when I touched a cracked distributor cap on an old Datsun while trying to get it running in the rain in a none too friendly part of Brooklyn. Yowza!

[Luke]

That's interesting. Despite the movie and TV shows where car batteries and jumper cables are used to inflict torture, I've never heard of anyone actually being shocked by 12V. I can grab hold of both posts of a car or heavy equipment battery and hold on all day without feeling a thing, and some of those are rated in the 1200 or more CCA range. I would guess that many engine starting motors are in the same hp / amperage draw range as the servomotor you're describing.

Were there odd conditions on that job?

I believe he's talking about a power supply that plugs into a 120 AC wall plug and then transforms it to D.C. D.C. usually has more amps but there's always if ands and buts.


We recently had a guy get hit with 7200v's and live to tell about it. In the hand out the feet. Scary stuff.

[Clusterfrack]

That's interesting. Despite the movie and TV shows where car batteries and jumper cables are used to inflict torture, I've never heard of anyone actually being shocked by 12V. I can grab hold of both posts of a car or heavy equipment battery and hold on all day without feeling a thing, and some of those are rated in the 1200 or more CCA range. I would guess that many engine starting motors are in the same hp / amperage draw range as the servomotor you're describing.

Were there odd conditions on that job?

Man, I don't know... Might have been 24VDC. High current for sure.

[theJanitor]

Getting hit by a MSD ignition box hurts pretty good. I got hit pretty hard by a 600amp, 220 volt main. Blew me about 7 feet off. That wasn't a fun experience

[farscott]

That's interesting. Despite the movie and TV shows where car batteries and jumper cables are used to inflict torture, I've never heard of anyone actually being shocked by 12V. I can grab hold of both posts of a car or heavy equipment battery and hold on all day without feeling a thing, and some of those are rated in the 1200 or more CCA range. I would guess that many engine starting motors are in the same hp / amperage draw range as the servomotor you're describing.

Were there odd conditions on that job?

It is possible that the 12V supply was not referenced to earth ground but was not floating. For example, I did a lot of power supply designs for inverters where we took 120VAC, rectified it to 170VDC, and then used a voltage doubler to create a 340V bus. That allows the use of smaller current for the same power, meaning lower conduction losses in the drive switches.

Then the microcontroller power supply would be set to 3.3V above the "ground" reference for the inverter. 3.3V is not much until you realize that the reference is now 170V BELOW earth ground as the voltage doubler midpoint is neutral. The designs were frequently around 1 hp (used about 410uF of equivalent capacitance to stabilize the DC bus) so touching that 3.3V rail would provide a nice jolt.

[JohnO]

Do not screw around with electricity. Especially multi-phase sources like 220 VAC and 480 VAC. The potential exists for Arc Flash. The energy released during an Arc Flash is nothing anyone wants to be near without the proper PPE Personal protective Equipment. I have seen the aftermath and it is devastating.

The following video illustrates what can happen and the individuals are not wearing proper PPE.

https://www.youtube.com/watch?v=J8auz60ma0A

[Jared]

I've taken two hits from 3 phase 480VAC. It's not fun, especially the one that went hand to hand and I still don't understand how that one happened.

Seriously, like was said above, do not screw around with electricity. I've been working with it for almost 15 years and have been quoted as saying "you'll never find another electrician that has as much respect for electricity as me."

[Wheeler]

I've been hung up on 277VAC, both the hot and the neutral, (at separate times.) It hurts. A lot. Very few folks have actually been hit by 480 as they would have to make contact with two separate current carrying conductors (hot wires,) to actually have 480 V pass through them.

Arc Flash is a real thing. The video above shows an extreme example, it's one of the training videos we have to watch occasionally. It is not nearly as likely to happen in what is considered a low voltage system, typically referred to as 120/208 VAC. It is much more likely in what is referred to as a high voltage system, (277/480VAC.) keep in mind that 220VAC is the typical voltage in domiciles in the USA.

[Wheeler]

I've taken two hits from 3 phase 480VAC. It's not fun, especially the one that went hand to hand and I still don't understand how that one happened.

Seriously, like was said above, do not screw around with electricity. I've been working with it for almost 15 years and have been quoted as saying "you'll never find another electrician that has as much respect for electricity as me."

That shit will put the fear of God in one for sure.

[ranger]

I made the mistake of putting a steel feeler gauge in between the points on an old Mustang with the ignition switch on - maybe it was only 12v but it was all I wanted!

[JAD]

In my new job I play with batteries, sized to propel ferries or source power for directed energy weapons. After years in RF and AC, I have a newfound respect for DC.

[BobM]

Thanks to the OP for bringing this up. The power company used to put on a safety presentation for police, fire, and street dept workers. We've had quite a bit of turnover since we last had them come in. I'm going to see if we can get them to do it again.

[octagon]

Bunch of pansies. I took 50,000 volts for 5 seconds........voluntarily.

Plenty of people have on a TASER ride.

[Wheeler]

There's taser voltage and then there's the stuff that kills you. Not only does it kill you it hurts the whole time you are dying. ;)

[UNK]

There's taser voltage and then there's the stuff that kills you. Not only does it kill you it hurts the whole time you are dying. ;)
I don't remember mine. Except the last part where I had a brief moment of clarity and I thought if I don't get off of this it will kill me. Somehow I did. In my hand and out my face into the snowbank I was laying in. Burnt marks all over my face and from the exit wounds and covered in blood. If I ever find out who put that illegal under ground box in then spliced the wires with wire nuts I will surely kill them.

[Maple Syrup Actual]

My best shock was back when I worked for a telephone company. Typical phone voltage here is around 52v at 85 mA, so if you're hunting for a live pair you can tap them on your tongue and it's like a 9v battery on steroids. It's pretty old school and most guys don't do it now, but it's really quick and back then I used to climb poles a lot and splice wires and I got paid piece rate so I got really fast.

But that's just dial tone voltage. RING voltage is around 90v AC. And if someone, for some weird reason, is ringing the line at the exact moment you touch it to your tongue, and you're going really fast so you only have one spur dug into the pole because you were used to doing the whole operation in a few seconds so you just dug in one and hooked the other around the pole...WHAM.

Knocked me right off my spur. Got lucky and got a hold of the pole and only slid down about four or five feet before my spur dug back in. Took me a few minutes to figure out what had happened, and I realized ring voltage because my tongue felt bruised. Must have gripped the telephone pole reflexively because I had no idea where I was for a few seconds.

After that I always wore my climbing belt.

[Drang]

Bunch of pansies. I took 50,000 volts for 5 seconds........voluntarily.

Plenty of people have on a TASER ride.

Again, VOLTS are not AMPS.

[Welder]

Again, VOLTS are not AMPS.

Right, this is why the vast, vast majority of people are alive and well after taking hits from electric fences and vehicle ignition systems, which also go into the tens of thousands of volts. Heaven knows I've been hit by plenty of both in my younger days which were spent first on a farm and then as a mechanic.

I'm currently a welder, so I also have the experience of being shocked through sweat-soaked welding gloves while changing rods. Welding in the rain is not a fun job either, as you can imagine. There you're generally talking DC current (AC for aluminum TIG) in the range of 16-40V (OCV can run to nearly 100V) and amperages ranging from 50A for tiny stuff to the max 575A that my 6-cylinder engine drive will put out while arc gouging.

[RolandD]

My best shock was back when I worked for a telephone company. Typical phone voltage here is around 52v at 85 mA, so if you're hunting for a live pair you can tap them on your tongue and it's like a 9v battery on steroids. It's pretty old school and most guys don't do it now, but it's really quick and back then I used to climb poles a lot and splice wires and I got paid piece rate so I got really fast.

But that's just dial tone voltage. RING voltage is around 90v AC. And if someone, for some weird reason, is ringing the line at the exact moment you touch it to your tongue, and you're going really fast so you only have one spur dug into the pole because you were used to doing the whole operation in a few seconds so you just dug in one and hooked the other around the pole...WHAM.

Knocked me right off my spur. Got lucky and got a hold of the pole and only slid down about four or five feet before my spur dug back in. Took me a few minutes to figure out what had happened, and I realized ring voltage because my tongue felt bruised. Must have gripped the telephone pole reflexively because I had no idea where I was for a few seconds.

After that I always wore my climbing belt.

I've had the pleasure of experiencing ring voltage, also. Fortunately, I was sitting in the floor of a office trying to find the one pair out of a 24 pair that was live. Found it just as it began to ring. ;)

I think the worst shock was while replacing a wall outlet, hot. Dumb, I know, but it was an old house with fuse box and the whole house was on two twenty amp fuses and I was doing this a night. While sitting cross legged in the floor, I accidentally made contact. Next thing I know, I'm standing about six feet from the wall, stunned. As was my wife who had watched the whole thing. I had flipped over backwards and landed on my feet. I later found out that the previous tenant had put pennies behind the fuses.

[txdpd]

I say fairly certain because electricity can be rather fickle. There may exist a path of least resistance outside of the obvious.

Back in February I watched a guy die that was walking too close to a downed power line. There is less resistance through one foot, up the body, and out the other foot, than there is through the ground between the feet. He was 30 feet away from the line. I don't know how many times I've been closer than that to downed line.

[Doc_Glock]

Most memorable burn of my time in the burn unit was a line worker who arced something from an arm down to his legs/buttocks. He came in alive and screaming and smelling horrible.

He died of sepsis after a month, much heroic, tortuous care and several amputations.

Now that I think of it, that was the worst case of my entire residency.

[DallasBronco]

It is possible that the 12V supply was not referenced to earth ground but was not floating.
I agree with this. It is the lack of a reference that kept you safe. A battery has voltage potential, but must be referenced to a ground to conduct current.

[peterb]

Dry intact skin should be insulation to 50V. That's where the OSHA standards for guarding jump up.

Automotive -- If you're downstream of the coil(older cars)you're talking thousands of volts. The voltage has to be stepped up to jump the spark gap. The other big danger is accidentally shorting the battery(wrench, screwdriver, etc.) -- it's only 12VDC, but there's a lot of current available for a short time, and the flash can be nasty.

If you HAVE to approach unknown wiring, use the back of your hand. If it's live, the reflex will probably pull your hand away instead of clamping on.

[WobblyPossum]

When I was four, I stuck a pair of tweezers into a wall outlet. I remember a small lightning bolt coming out of the wall and hitting me in the knee and ten running around screaming for a bit. Let's just say I learned my lesson and haven't messed around with electricity since. Sometimes I think that Otto Von Bismark was thinking about me when he said "God has a special providence for fools[...]."

[Welder]

Back in February I watched a guy die that was walking too close to a downed power line. There is less resistance through one foot, up the body, and out the other foot, than there is through the ground between the feet. He was 30 feet away from the line. I don't know how many times I've been closer than that to downed line.

We had a line go down on the farm years ago, and the first clue was a pile of dead steers near it on the ground. There were 17 of them in the pile, but one, near the middle, was alive. My Dad first realized this when he saw it blink. That steer lived on with no apparent lasting ill effects.

[schüler]

[QUOTE=TBone550;613932...I've never heard of anyone actually being shocked by 12V. I can grab hold of both posts of a car or heavy equipment battery and hold on all day without feeling a thing, and some of those are rated in the 1200 or more CCA range...[/QUOTE]

12V doesn't have the "pressure" or high voltage but will definitely conduct higher current when conditions are right. Imagine a 9v 200A battery on your tongue... or stun fishing with 12v batts.

A servo drive is not simple, switched DC but pulsed per load/speed equirement. It is similar to AC in some ways. A 2hp servo drive has around 130 amp potential, pulsed to steady.

Between ages of 14 and 19 I'd pissed on hot fence (accidentally), cut off my own 120v power cord using an old metal framed circ saw, shorted unfused 100A/240V service (phase to phase), blown ditches in wrenches with 540V battery strings and built several electric rat traps with fused 120 volt. I swear rats can sense electricity. Not a single one got lit up. Didn't have any more problems from barn rats eating all the seed in my bird feeder overnight either.

Have kept it pretty sane since then except for a few hot work instances.

[Coyotesfan97]

Back in the early 90s when I was a young guy working graves I took a suicide report. Guy was found in underwear and to quote a witness "looked like Don King". He had climbed into an SRP substation and onto one of the machines/boxes that dropped the voltage down from the high voltage lines. It blew him off and burned him pretty badly. SRP had to shut stuff down to check the facility. They called me back after they located his property. The SRP guy told me it must've arced and knocked him off because if he had latched onto the wires he would have been nothing but meat.

[TheCarl]

Bunch of pansies. I took 50,000 volts for 5 seconds........voluntarily.

Plenty of people have on a TASER ride.

"It's the volts that jolts, but the mils that kills."

[schüler]

"It's the volts that jolts, but the mils that kills."
Them MCMs tho.

[NEPAKevin]

New Jersey driver killed after driving around barricade onto live wires (http://www.foxnews.com/us/2018/03/08/new-jersey-driver-killed-after-driving-around-barricade-onto-live-wires.html)

https://twitter.com/ABC7NY/status/971798261219643392/photo/1?ref_src=twsrc%5Etfw&ref_url=http%3A%2F%2Fwww.foxnews.com%2Fus%2F2018%2 F03%2F08%2Fnew-jersey-driver-killed-after-driving-around-barricade-onto-live-wires.html

[Stephanie B]

Bunch of pansies. I took 50,000 volts for 5 seconds........voluntarily.

Plenty of people have on a TASER ride.

In the words of a German electrical engineer, back when they were electrifying the New York Central Railroad into Grand Central Station: "To hell mit der volts, it's der amps that count."


Sent from my NSA-approved tracking device via Tapatalk

[Darth_Uno]

Current kills. Just touching a 110 or even 220 line won't necessarily do anything. I build homes, and was previously primarily an electrician, and it still amazes me how many electricians don't really understand how electricity works.

I also brushed a live 200 amp terminal with my knuckle and it knocked me straight on my ass and I saw stars. Felt like a punch in the chest by Mike Tyson in his prime.

Been shocked a few other times. I'm ok. *head shakes uncontrollably*

[OlongJohnson]

I swear rats can sense electricity. Not a single one got lit up. Didn't have any more problems from barn rats eating all the seed in my bird feeder overnight either.


No question. Cars parked long term often have the wiring systems eaten by rats. Literally everything under the hood that has electricity inside it gets attacked. I have no idea why they do this.

Take the battery out to prevent it.

[FNFAN]

Current kills. Just touching a 110 or even 220 line won't necessarily do anything. I build homes, and was previously primarily an electrician, and it still amazes me how many electricians don't really understand how electricity works.

I also brushed a live 200 amp terminal with my knuckle and it knocked me straight on my ass and I saw stars. Felt like a punch in the chest by Mike Tyson in his prime.

Been shocked a few other times. I'm ok. *head shakes uncontrollably*

My Uncle had a contract for building out the old Spies groceries. Always cussed about getting hit on the commercial freezer units which I recollect him saying were 480. Also told a story about refurbishing homes on the reservation said those were some of the poorest wired dwellings he'd ever seen and some of the most creative "improvements" he'd seen.

[Hambo]

Electricity is magic. I've only been zapped by 110 and stun guns and can't say I enjoyed any of it.


https://www.youtube.com/watch?v=VRaoHi_xcWk

[Hemiram]

Getting hit by a MSD ignition box hurts pretty good. I got hit pretty hard by a 600amp, 220 volt main. Blew me about 7 feet off. That wasn't a fun experience

I got a double hit by an MSD box about 40 years ago. I had a '77 Dodge "Macho" Power Wagon, and had an MSD 6C box on it, with a huge coil and the pretty expensive Blue Max wires. The truck was a total piece of garbage and had constant issues. It developed a miss, which turned out to be a carb issue, but I thought it was an ignition problem. It was dark out, about 11PM, and I was standing on a plastic milk crate, leaning over and I had the lights off in my garage, so I could see any sparks jumping. It was, as it tended to be in Vegas, 100 degrees and I was sweating a ton. I had dripped sweat all over the milk crate, and I started to fall. I grabbed the coil wire and leaned forward as far as I could, pressing myself hard against the front right quarter panel. My pants were soaked and the fly was messed up on them, and the zipper was exposed. Apparently, my junk had come into contact with the zipper, which grounded itself to the truck, and my junk got zapped. Well, more than zapped. I had a rag in my right hand that insulated it from the radiator mount, so all the hits went through my junk into the zipper. I "danced" around for a few seconds, and fell off the truck. I didn't know what happened, "down there" for a while, but when I went into my bathroom, my shorts were full of blood. At the tip of my penis, I had a hole blown into it! When I took a shower, I found I had a tiny hole in my sack, too. Both bled way more than I expected they ever would. I doctored myself with Neosporin or whatever it was that I had and everything healed up fine. But I was paranoid when I got near the plug wires on that truck when it was running. A few years later, I would have a much less traumatic burn/hole in my hand when I somehow touched the messed up coil wire on my '79 Trans Am that had an MSD 6 box with one of those giant Accel coils on it.

When I was in high school, I had a CB with a 300 watt linear on it. I talked all over the world on it. The linear was very hard on tubes and I had to replace them several times. One time I was home sick with the Flu and I decided to change out the tubes before bedtime, in case the skip was rolling the next morning, so I could just fire up and start talking. Instead of my insulated shaft screwdriver I had made just for the job of tuning a variable cap to set the tube up, I used a regular one, thinking, "I'm not a dope, I'll be fine!". I was keyed up and talking to a friend of mine, and the next thing I know I was flying into my closet door, knocking it off track and landing on my boots and shoes. I had pulled out the mike cord from the plug and my friend said he heard a loud "BZZZZZT", and me scream before the radio stopped transmitting. I was pretty shaken up and my right index finger was a little burned and my heart was pounding like a machine gun. I went to school in the morning and was kind of shaky all day. My teeth were chattering at lunch. After that, I was super careful and managed to do several tube swaps without any issues and avoid all electrical shocks until the above incidents.

[peterb]

Worst shock I ever had was from a 12 VDC power supply for a 2hp servomotor. It kicked my ass and left me on the ground. Way worse than any of the 120 VAC shocks I've experienced.

Just rereading this thread. A lot of AC/DC power supplies have huge capacitors to smooth out the rectified AC. They can kick your tail even after the equipment is powered down.

[Joe in PNG]

Just rereading this thread. A lot of AC/DC power supplies have huge capacitors to smooth out the rectified AC. They can kick your tail even after the equipment is powered down.

As a tube amp builder, this is so true. I have a custom jumper with a 220v/2a resister soldered in for draining the caps before I do anything inside, and will probably hardwire a cap drain into everything later.

[11B10]

First, I don't trust anything I can't see. Let me rephrase that: If you SEE electricity, it's way too late. I had a good friend, well-versed in electrical work, who was electrocuted while lying on his back, drilling holes in the bottom of his camper. He was lying on damp grass, using a small drill, 110 current. Apparently he closed the circuit between the grass and a bad cord with his body. No one remembers him ever talking about the bad cord. I've been jolted many times - probably the worst one was when I was working on a truck's carburetor, kneeling atop the fender. It was an HEI (high energy ignition), 1977 Chevy. Anyway, I began to slide and to stop the slide, I reached out and grabbed the nearest thing - the distributor. HEI generates around 40,000 volts. I ended up about 10' away, ears ringing - guess that's what "getting your bells rung" means.

[JohnO]

Just rereading this thread. A lot of AC/DC power supplies have huge capacitors to smooth out the rectified AC. They can kick your tail even after the equipment is powered down.

I know of a case where a guy was killed by the energy stored in a large capacitor. Never assume Zero Energy. Always Verify!

[Hemiram]

I was putting in a C Band dish in the summer of 1999, and I had to drill a couple of holes in my foundation to pass the cables though. I was sitting on the ground and I was using the giant, I'm talking colossal drill I bought when I was in high school. It had an all steel gearbox with 2 speeds in it, even at the high speed, it could twist itself loose if it stalled. So I put my 3/4" bit into it and start to drill the hole. I got zapped and yelled, "Yow!!", and for some odd reason, I pulled the trigger again, with the same result. I jumped up and pulled the extension cord out of the wall and took the drill in and fixed it. About 20 minutes later, I had a hole in my foundation along with a huge bruise on my arm from when the drill stalled right at the end, and I was probably lucky to not have had a broken arm. That drill needed a clutch, badly.

[RJ]

Wow.

Good stories.

As a EE, it amazes me people survive some of this stuff. Glad you guys are around.

To date, I’ve managed to avoid anything serious, myself.

One cool story bro; my intern job summer of 1981 was with the Naval Research Lab. We had a task to do some RF (mm wave) testing out on a jack up barge in the Chesapeake Bay.

Visiting the shore side part of the site, I distinctly recall being told I really should not walk in front of the emitter array while it was transmitting if I ever wanted to have kids.

I’m not sure they weren’t kidding. [emoji41]