gayler
Well-known member
Just wondered. As a hobby I tinker with tube amps that have voltage DC. I am well aware of safe practices with these.
Which is more dangerous A/c voltage or DC?
- Thread starter gayler
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matt151617
Well-known member
Amps kill you, not volts. Tasers for example are 50,000 volts but a tiny fraction of 1 amp. In high amps both are equally dangerous.
FJ 432
Well-known member
DC the worst. Can't let go.
rlitman
Well-known member
Both have their hazards. HV DC is more likely to sustain an arc in air, so that's one additional danger of it.
Ask Edison! He really did have a nation wide campaign to demonstrate the horrors and dangers of AC versus the more safer DC.
The good old answer of course though, is it depends. Although, generally AC is more dangerous. There are a few studies stating that AC at common household frequency is significantly more dangerous than DC at the same voltage and amperage. Additionally while DC may be inclined to stop one's heart, AC has a greater propensity to throw one's heart into fibrillation. In both events you'll die without advanced medical treatment and a defibrillator. However there are studies showing that you're more likely to be revived and receive less heart damage with DC than AC. Unfortunately DC is also likely to have some unpleasant secondary effects in your body, should you live.
At higher voltages, DC is more likely to sustain in arc than AC, as rlitman mentioned.
As for being able to "Let Go" of an energized conductor, that is more of a matter of current. With something like 9-15mA being the limit. While theoretically you might be able to let go of AC at the zero-crossing, that's mere millisecond's, and unlikely in practice.
Regardless, both are quite effective killers that should be carefully respected.
The good old answer of course though, is it depends. Although, generally AC is more dangerous. There are a few studies stating that AC at common household frequency is significantly more dangerous than DC at the same voltage and amperage. Additionally while DC may be inclined to stop one's heart, AC has a greater propensity to throw one's heart into fibrillation. In both events you'll die without advanced medical treatment and a defibrillator. However there are studies showing that you're more likely to be revived and receive less heart damage with DC than AC. Unfortunately DC is also likely to have some unpleasant secondary effects in your body, should you live.
At higher voltages, DC is more likely to sustain in arc than AC, as rlitman mentioned.
As for being able to "Let Go" of an energized conductor, that is more of a matter of current. With something like 9-15mA being the limit. While theoretically you might be able to let go of AC at the zero-crossing, that's mere millisecond's, and unlikely in practice.
Regardless, both are quite effective killers that should be carefully respected.
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Jarcese
Well-known member
I've seen this mentioned here a few times before, but when Edison(DC) and Westinghouse + Tesla(AC) were battling for supremacy, Edison staged a public electrocution of an elephant in NYC to try to prove which was more dangerous. They filmed it and killed it in front of a few thousand people. Pretty sad actually... Edison seemed like a bit of a *******, but seemed to get credit for the way we use electricity today even though he tried so hard to destroy AC theory.
I say it depends on the voltage, not current. I get why people say current is the factor, but don't really agree. 1 amp at 120 volts can kill you mostly from throwing off your heartbeat, it's not very likely at all. 1 amp at 25kv you would be lucky to die or spend a year in a burn unit and wake up with no face or arms.
Both have their reasons for being dangerous, but it really all depends on the voltage and amps combined.
Didn't see the post above mine until after I submitted.
I say it depends on the voltage, not current. I get why people say current is the factor, but don't really agree. 1 amp at 120 volts can kill you mostly from throwing off your heartbeat, it's not very likely at all. 1 amp at 25kv you would be lucky to die or spend a year in a burn unit and wake up with no face or arms.
Both have their reasons for being dangerous, but it really all depends on the voltage and amps combined.
Didn't see the post above mine until after I submitted.
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nehog
Well-known member
Define dangerous!
The rule of thumb is that AC is more likely to cause fibrillation. Both AC and DC are about the same in the "can't let go" department.
The rule of thumb is that AC is more likely to cause fibrillation. Both AC and DC are about the same in the "can't let go" department.
ForceFed70
Well-known member
At school (Electrical Engineering Technology) we were taught that DC is the most dangerous as you cannot let go.
Jarcese
Well-known member
Yeah AC gives you a chance to let go 60 times in a second... in North America anyway. Don't know many people gifted enough to move that fast.
Jose G
Well-known member
DC is more dangerous (cant let go). both can kill.
RECox286
Well-known member
Q. Which is more dangerous, AC or DC ?
A. Yes.
Uncle Bob
A. Yes.
Uncle Bob
Jarcese
Well-known member
^Good answer
People who think DC is worse, your body can't tell the difference between 60 cycles a second and constant voltage... you guys must be more sensitive than most.. kidding of course.
If you really do the math, 120 volts is 170 volts peak to negative peak. So by that math would that make 120v ac(170 peak to peak) more dangerous than 120v DC or less? I'm asking 'cause my brain hurts...
I had an old lady yell at me one time because she thought we were putting people in danger by using AC.. I really didn't have a reason to tell her why which one was safer. She didn't want to hear anything about why AC is easier to distribute.
People who think DC is worse, your body can't tell the difference between 60 cycles a second and constant voltage... you guys must be more sensitive than most.. kidding of course.
If you really do the math, 120 volts is 170 volts peak to negative peak. So by that math would that make 120v ac(170 peak to peak) more dangerous than 120v DC or less? I'm asking 'cause my brain hurts...
I had an old lady yell at me one time because she thought we were putting people in danger by using AC.. I really didn't have a reason to tell her why which one was safer. She didn't want to hear anything about why AC is easier to distribute.
Speedy Petey
Well-known member
This quote always gets me.
It's NOT the amps of a circuit, appliance or thing that kills anyone. It is amperage flowing through the body that does harm. You can get just as killed from a 120V 15A lamp cord as you can from one leg of a 240V 1200A switch gear.
It's all in how the voltage is delivered to the body. A taser will only ALLOW a certain amount of current to flow. Just like a GFI receptacle. You will still get a shock, but it will not allow the amperage to reach lethal levels.
At the same time, you can grab a 12V 1000CCA car battery by the terminals and not feel a thing. It's the voltage that is so low it is not allowing the amperage to flow through your body since the body's resistance is so low to such a low voltage.
So saying "it's not the voltage that kill, it's the amperage" is not entirely true.
Jarcese
Well-known member
Also, everyone's body has a different resistance. A callus on your fingertips could be the difference between getting hurt or not feeling a thing. In theory of course.. do not try at home.
err...13,200volts?? Yea it kills...just ask these theives...I have the rest of the pictures..but they are very very very very graphic...so let me know if you want to see them.
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View attachment 225469
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ihatelaramie
Well-known member
So.. were they trying to steal copper.. from a live line?
Of course that statements true! It's just not defined what it's in reference too!
Now we're getting into semantics 
I'm a bit solemn over apparently so many schools teaching people that you can't let go of DC while you can let go of AC though. Too many people here have posted similar things. It's especially sobering when you consider that in some cases the let go thresholds of AC are significantly less than that of DC.
I suppose technically you could with one hand grab one phase of an energized 40KV conductor while holding a ground with the other hand... if you're quick enough. Come on, there's more than a few zero-crossings in a given second... Just remember to calculate the potential difference to ground in that equation as well... Shoot, your millisecond is over, sigh - we're dead.
Shockingly enough, no pun intended, and to point out the scary nature of how complicated this all can become. I know of a crew who unwittingly worked on some energized equipment of similar voltage... and due to some miracle, none were even hurt.
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rsanter
Well-known member
There is no difference. It's not the type (AC or DC) and it's not the voltage (directly) it is the amount of electricity that goes through you (amps) that will do the damage and will kill you.
Electricity will take the path of least resistance including through you.
Being exposed to an arc flash can get you too, the arc will super heat the surrounding air to a couple thousand degrees and can cook you.
By the way, I do electrical training and electrical safety
Bob
Electricity will take the path of least resistance including through you.
Being exposed to an arc flash can get you too, the arc will super heat the surrounding air to a couple thousand degrees and can cook you.
By the way, I do electrical training and electrical safety
Bob
I pretty much agree wholeheartedly, for all intents and purposes they both should be treated as deadly as they are. However there are dramatic differences in the characteristics of AC current versus DC current on the human body, even from similar voltages.
y20dth
Well-known member
I was taught the same thing.
Yep...STUPID!! The small about of copper in the Highvoltage lines is not worth it...I installed plenty...Lower voltage 1000mcm..now that is some cash..lol. Rule of thumb is your close to it and your hair stands on end on your arm...do not touch it..your already to close..lol. Here is another shot that is not too bad...
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Shockingly enough, no pun intended, and to point out the scary nature of how complicated this all can become. I know of a crew who unwittingly worked on some energized equipment of similar voltage... and due to some miracle, none were even hurt.[/QUOTE]
You can with Hot Gloves, Hot Blanket, and overall, as well as tools built for it...normally tools that have a 5 foot reach...if your not grounded ( touching earth, metal) or anything else your good. You should see the guys that hang out of a Helecoptor and change the insulators on super high voltage..now that is an insane job..
You can with Hot Gloves, Hot Blanket, and overall, as well as tools built for it...normally tools that have a 5 foot reach...if your not grounded ( touching earth, metal) or anything else your good. You should see the guys that hang out of a Helecoptor and change the insulators on super high voltage..now that is an insane job..
wyliesdiesels
Well-known member
Keep in mind that electricity 12kv and up is pyrophoric so if u have an arc, the air will catch on fire!
I have to agree with u Pete!
I'll check 'em out! Send me a private message if u don't want to post them here.
I have to agree with u Pete!
I'll check 'em out! Send me a private message if u don't want to post them here.
Yes, I used to do all of that, minus the helicopter line work. However that crew actually climbed in the wrong metal clad switch gear cubicles and started disassembling an energized bus without any protection. After removing the bolts holding the bus bars on insulators, they took a break to reassess why all of the hair on their arms was standing up... An absolute miracle no one was killed or injured.
Worldpowerlabs
Well-known member
- Joined
- Jul 3, 2011
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It's a bit more than that... 120Vrms = ~170v peak, which is from the zero-volt crossing point to either the negative peak or the positive peak. (i.e., Vp = 1.414*Vrms). However, peak-to-peak is 2*Vp = ~340 Vpp.
As for whether your body feels the effects of the full pk-pk voltage, or whether 120Vac (RMS) is similar to 120Vdc in terms of biological damage, I suspect that the former is worse, but I'm not a biology expert -- just an electronics engineer.
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Speedy Petey
Well-known member
It's not semantics. It is a very important distinction IMO.Of course that statements true! It's just not defined what it's in reference too!
The whole "it's the amps" thing conveys the dangerously wrong impression that a 15A wall receptacle is somehow less dangerous than a 200A service panel.
They are both 120V and THAT is what matters.
nehog
Well-known member
Yep, you can't recover and make a muscle movement in that time period. So no difference what so ever in that respect.
Interesting fact: fewer people are killed with 240 volts than with 120 volts (adjusted, this study was done by studying electrocutions in both countries where 120 volts was common, and countries where 240 (or 220) volts was the standard. It turned out that the higher voltage was safer. There was some debate as to whether people were more careful with 240 volt power (are we complacent with 120 volts?) but the general consensus was that 240 tended to throw people's hands off the circuit more often than 120 did.
As for those who say that they were taught that DC was more dangerous than AC, I can only say that sometimes we are taught the wrong thing. Both are at least as equally dangerous though AC perhaps more so because it more easily causes fibrillation is more dangerous. Sorry: that is just the way it is!
In the majority of the acknowledged research on the matter that I've read, they use peak AC values versus RMS, due to how it effects the body.
Rated ///M
Well-known member
check out this video... Pretty interesting...
Jarcese
Well-known member
I'm surprised the power in India stayed on for enough time to film that.
How pissed was he that the guy threw the egg on the hot plate. You can tell he was thinking, "thanks *******, I'm not immune to boiling hot eggs on my arm".
How pissed was he that the guy threw the egg on the hot plate. You can tell he was thinking, "thanks *******, I'm not immune to boiling hot eggs on my arm".
Jose G
Well-known member
people who said DC is more dangerous have been taught the right thing.
AC is known to stop the heart and DC has the "cant let go" factor. both are dangerous and can kill/burn you.
NO ONE prefer to stay connected while been shocked without been able to move a finger, yell, etc... that's the reason why DC is "more dangerous".
the fact is people rarely see DC current high enough to kill them / shock them. they usually see AC current 90% of the time.
this question is like asking how much water do you need in your pool to make it dangerous, or how many MPH do you need to go to be in the dangerous spot?... there's no real answer, its always dangerous.
AC is known to stop the heart and DC has the "cant let go" factor. both are dangerous and can kill/burn you.
NO ONE prefer to stay connected while been shocked without been able to move a finger, yell, etc... that's the reason why DC is "more dangerous".
the fact is people rarely see DC current high enough to kill them / shock them. they usually see AC current 90% of the time.
this question is like asking how much water do you need in your pool to make it dangerous, or how many MPH do you need to go to be in the dangerous spot?... there's no real answer, its always dangerous.
racingtadpole
Well-known member
Reality is AC is more dangerous, because it is somewhat more abundant in the number of places it is found. AC is literally everywhere. Big DC setups are generally speaking only found in industrial applications.
It really is a pointless question, they both have the potential to kill you if not treated with the respect they deserve.
It really is a pointless question, they both have the potential to kill you if not treated with the respect they deserve.
wyliesdiesels
Well-known member
Huh? The egg was cooking on a hot plate not directly on the guys arm. I'm still skeptical because I couldn't tell how the indian guy completed the circuit. Yes, he had wire wrapped around himself(during the hot plate experiment) but it looked like the wire around his chest was connected to the wire on the table and then the wire under his foot and wrapped around his waist went to the hot plate as well. If the hot plate was not directly connected to the outlet, then it would have meant that the electricity was flowing through the hot plate via induction over the guys body.
And the experiment with the light bulb is possible with anyone. When I took electronics in high school, the teacher had a tesla coil which he rolled out and plugged in with each new class. He would have a few of his students hold one end of a light bulb(fluorescent) up to the tesla coil and all the students in the class would watch in amazement as the bulb lit up!
Jarcese
Well-known member
Looked like it fell off the plate the first time I watched it. Video looked a little fishy for sure. I'm sure that meter was extremely accurate.
Does anyone have any real numbers as to which is more dangerous? We've established that electricity is dangerous and speculated that DC makes you hang on, which I don't believe your body can tell the difference. Both current types are going to make you hang on if you wrap your hand around two points of contact and at high voltages they will both blow you away from the conductors.
What if the question is; What is more dangerous at 120v and 5amps?
Does anyone have any real numbers as to which is more dangerous? We've established that electricity is dangerous and speculated that DC makes you hang on, which I don't believe your body can tell the difference. Both current types are going to make you hang on if you wrap your hand around two points of contact and at high voltages they will both blow you away from the conductors.
What if the question is; What is more dangerous at 120v and 5amps?
nehog
Well-known member
Re-read this thread. The questions have been answered (both of yours) above. Hint: that '5 amps' is meaningless. It takes less that 120 MA (that is 0.12 amps) and it is possible that currents as low as 20 MA (that is 0.02 amps) can be lethal.
Since it has already been stated that AC is much more likely to cause fibrillation I don't see much need to continue to bash the subject.
Jarcese
Well-known member
I just threw that number out there, I realize that less amperage can be deadly. I wrote AC is more likely to throw off heart rhythm.. I said it in my first response.
Discussion over then. Lets move on to more discussions on how to run wire to a sub panel.
Discussion over then. Lets move on to more discussions on how to run wire to a sub panel.
Speedy Petey
Well-known member
Why? It's a worthwhile discussion.
The question is, what does that 5A you mention represent?
Jarcese
Well-known member
I was being a little sarcastic. What I was looking for is the difference in what you feel on a specific amperage when you compare currents. Five was a big number, I shouldn't have used 5amps as an example since I guess it wouldn't matter.
I was looking for a comparison like in the chart on the middle of this page:
http://www.allaboutcircuits.com/vol_1/chpt_3/4.html
I was looking for a comparison like in the chart on the middle of this page:
http://www.allaboutcircuits.com/vol_1/chpt_3/4.html
ddawg16
Well-known member
So much misunderstandings.....
In most cases, what really kills a person is the muscle tissue being cooked by the current flow...
Each type of shock has it's own issues....arch flash causes burns on the body....
A common injury....someone touches a high voltage point...it goes in the hand...discharges through the elbo or other part of the body....depending on the power....(I said power which means a combination of voltage and current), the power will cook the meat in the body...once that happens....that body part is dead...if it happens across the heart...guess what....won't beat....
We had a local new reporter loose her arms due to high voltage...the TV van tech raised the broadcast mast into some high voltage power lines....she panicked and jumped from the van with her arms holding the door edge....it cooked the muscles...she lost her arms....
In most cases, what really kills a person is the muscle tissue being cooked by the current flow...
Each type of shock has it's own issues....arch flash causes burns on the body....
A common injury....someone touches a high voltage point...it goes in the hand...discharges through the elbo or other part of the body....depending on the power....(I said power which means a combination of voltage and current), the power will cook the meat in the body...once that happens....that body part is dead...if it happens across the heart...guess what....won't beat....
We had a local new reporter loose her arms due to high voltage...the TV van tech raised the broadcast mast into some high voltage power lines....she panicked and jumped from the van with her arms holding the door edge....it cooked the muscles...she lost her arms....
Speedy Petey
Well-known member
This is my point. The "current" of the circuit does not matter one tiny bit. It is the current flowing through you that matters.
You can get 5mA flowing from many sources, from a 5mA source to 2000A or greater.