120 volts AC vs 120 volts DC shock

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kwired said:
You also were not in the path of 200 amps of current,
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Does making series connections on the battery terminals count?
the voltage needs to be very high to be able to push 200 amps through an average human body. Even if you put yourself in series with that 200 amp load @ 24volts - your body resistance is so much higher then that of the load that practically no current is flowing - need really low scale measuring devices to read what little is flowing.
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So your saying that you need enough voltage before any number of amps can do harm? If you are then I agree.
 
ActionDave said:
Does making series connections on the battery terminals count?
So your saying that you need enough voltage before any number of amps can do harm? If you are then I agree.
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I am saying you can just put yourself in series in a path that normally carries 200 amps and expect that same 200 amps to flow when you are part of the path, because you (should) have a higher resistance then the conductor you replaced in the path.

Raise the voltage enough though and you can get 200 amps to pass through you, but also remember as you cook, your resistance probably increases meaning even higher voltage is needed to achieve 200 amps.

You did mention this 200 amp circuit only had 24 volts behind it.
 
I thought one of the arguments Westinghouse used to win out his AC over Edison's DC was that DC was so much more dangerous for shock at 120v level.... course his proving it with electrocuting an elephant on DC did not help his argument with lots of people.....

I thought there were studies showing DC was more deadly at same marginal voltage as AC due to not being kicked off it (can't let go).

The question was which was more dangerous for shock at 120v, not necessarily involving an earth ground, but since earth ground contact was mentioned......

I post to ask if anyone ever tried to put 120vdc into a ground rod and tried to get anything from another even one a few inches away?

I had only 75vdc available for an experiment, but conclusively proved to my self that this low a voltage level will not conduct thru earth; you need AC or very very high DC voltage (researching why, I found AC does something to the chemical makeup of the earth in contact with the ground rod that allows low impedance).
 
mike_kilroy said:
I thought one of the arguments Westinghouse used to win out his AC over Edison's DC was that DC was so much more dangerous for shock at 120v level.... course his proving it with electrocuting an elephant on DC did not help his argument with lots of people.....

I thought there were studies showing DC was more deadly at same marginal voltage as AC due to not being kicked off it (can't let go).

The question was which was more dangerous for shock at 120v, not necessarily involving an earth ground, but since earth ground contact was mentioned......

I post to ask if anyone ever tried to put 120vdc into a ground rod and tried to get anything from another even one a few inches away?

I had only 75vdc available for an experiment, but conclusively proved to my self that this low a voltage level will not conduct thru earth; you need AC or very very high DC voltage (researching why, I found AC does something to the chemical makeup of the earth in contact with the ground rod that allows low impedance).
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Big difference between your small system and the grounding grid tied all over the POCO service area, and that grounding grid likely even interconnects at substations to grounding system of other systems, and we effectively have most of the utility grid of the entire continent all connected together and billions of electrodes are "earthing" all of it.

Try grounding a truly isolated AC source (no bond to the grounding system of the primary) and do some similar testing. I don't know what results you will get, but can tell you if you have a bond to the grounding portions of a utility supplied system, you have much lower resistance to ground because you have electrodes connected all over the place - at each building supplied, at nearly every pole or other structure, at substations, generation facilities, and probably some I missed. Then you likely will have with a single ground rod on an isolated system.
 
kwired said:
Big difference between your small system and the grounding grid tied all over the POCO service area, and that grounding grid likely even interconnects at substations to grounding system of other systems, and we effectively have most of the utility grid of the entire continent all connected together and billions of electrodes are "earthing" all of it.

Try grounding a truly isolated AC source (no bond to the grounding system of the primary) and do some similar testing. I don't know what results you will get, but can tell you if you have a bond to the grounding portions of a utility supplied system, you have much lower resistance to ground because you have electrodes connected all over the place - at each building supplied, at nearly every pole or other structure, at substations, generation facilities, and probably some I missed. Then you likely will have with a single ground rod on an isolated system.
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Interesting idea.... I do not think the millions of grounds around the continent do much for my two ground rods 100' feet apart that lite a 100watt bulb full brilliance on 120v ac and none on 75vdc (hooked directly to it, it lite nicely of course)....

I will test this wed when back to the lab! I have a nice 120v isolation xfmr I can use. My prediction is DC will not lite the lite but the isolated 120v will - chemical change of molecules bouncing around in contact with the ground conductor.... fun!
 
mike_kilroy said:
Interesting idea.... I do not think the millions of grounds around the continent do much for my two ground rods 100' feet apart that lite a 100watt bulb full brilliance on 120v ac and none on 75vdc (hooked directly to it, it lite nicely of course)....

I will test this wed when back to the lab! I have a nice 120v isolation xfmr I can use. My prediction is DC will not lite the lite but the isolated 120v will - chemical change of molecules bouncing around in contact with the ground conductor.... fun!
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I may have been thinking a little from the wrong perspective with that last reply. The public grid is definitely "earthed" much better then an isolated system because of all the millions of electrodes and interconnections via grounded conductors but I guess you can still have areas of raised potential simply because of voltage drop to a somewhat isolated area. The good is there is probably low enough impedance to effectively mitigate lightning and other surges, the bad is there is increased possibility of extraneous voltages.

I don't know if conductive ability of a single ground rod application is different for AC or DC assuming same RMS or effective voltage is applied.
 
mike_kilroy said:
Interesting idea.... I do not think the millions of grounds around the continent do much for my two ground rods 100' feet apart that lite a 100watt bulb full brilliance on 120v ac and none on 75vdc (hooked directly to it, it lite nicely of course)....

I will test this wed when back to the lab! I have a nice 120v isolation xfmr I can use. My prediction is DC will not lite the lite but the isolated 120v will - chemical change of molecules bouncing aY
round in contact with the ground conductor.... fun!
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Iam afraid Your prediction is bound to fail because ground resistance is afterall a resistance both for AC and DC.
 
Sahib said:
Iam afraid Your prediction is bound to fail because ground resistance is afterall a resistance both for AC and DC.
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I agree, resistance is resistance. If there is a difference it should be because there is an inductive or capacitive component in the path that will have different effects on the AC circuit and we call it impedance when we have those components in the circuit.
 
sbrehler said:
Having read these posts, I am wondering why it is that most people don't understand that that the Cardinal Rule of electricity is, "it isn't the voltage that kills you, it is the current!"
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Actually, it's both.
 
ggunn said:
Actually, it's both.
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Sometimes?paradoxically,neither:remember people sitting on metal plates connected to millions of volts high frequency Tesla coil ,high frequency current harmlessly passing over theit bodies and discharging into air as little lightnings.
 
Sahib said:
Sometimes?paradoxically,neither:remember people sitting on metal plates connected to millions of volts high frequency Tesla coil ,high frequency current harmlessly passing over theit bodies and discharging into air as little lightnings.
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Ah yes, the infamous "skin effect" using real skin....
But the performers who do the really spectacular effects wear Faraday suits just in case.
 
Here is the scan copy regarding experiment on significance of DC polarity in causing injury from 'Electricity and Man' by Manoilov, for your scrutiny.
 

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Sahib said:
Here is the scan copy regarding experiment on significance of DC polarity in causing injury from 'Electricity and Man' by Manoilov, for your scrutiny.
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Another mystery cleaned up: Wondered about that rabbit polarity claim amongst many totally erroneous posts along the way (e.g Edison electrocuted animals with ac, NOT George with dc - someone totally turned around story in that post, many others similar)

In regards to rabbits :: Calling PETA, calling PETA, animal cruelty underway....

Poor little rabbit were not electrocuted, the rabbit against the anode with Strychnine electrolyte received a fatal dose of Strychnine thru the skin as a result of the ionization of the electrolye quicker than the cathode side rabbit - electrons go to the anode and migration of ions thru the skin. Leave it on long enough with ac and both rabbits die, leave it off with rabbits having the shakes and both rabbits die with no electricity.

Article neglected to mention any timeline, assume the dead rabbit lived for 10-20 minutes before succumbing to chemical poisoning. Article is a good example of electrolyte migration thru permeable membrane.

Anyone who likes to think drinking ionized alkaloid water is healthful should wonder?

PS: am an old 'dried up' man, cannot even feel 120 Vdc with dry fingers, 120Vac just a tingle; wet is another matter as some of the better post discussed.

Another tidbit not covered is that electrocution is a matter of being connected during the T wave interval of your ECG. Thus, chance is a factor for momentary contact.
 
junkhound:
The article did mention the rabbit was killed the moment the power was switched on-no delay for any chemical ppisoning to.take into
account.!
 
iceworm said:
I'm a member of PETA*. What's going on?
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Poisioning, electrocution - sorry can't help.

*People for the Eating of Tasty Animals

ice
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You probably would NOT want to eat strychnine laced rabbit stew though <G> - or at least make sure you ate the cathodic rabbit?

One moment: 1.5 minutes, faster dead rabbit than I thought.
 
The chemical poisoning and death of the rabbit on the positive polarity side occurred immediately on switching on DC power supply, sparring the rabbit connected to the negative polarity side.
Thanks for the insight, guys.
 
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