human body is shocked by AC or DC ?

[waheeda]

hi friends
plz tell either DC or AC 40 amp current is felt by human body.

 

[Optikon]

hi friends
plz tell either DC or AC 40 amp current is felt by human body.

Either one can shock if the magnitude is sufficiently high.

40amps of current flowing in human body will definately be felt.

There is much controversy of what safe levels are but this is typical.

Voltages under 42Vrms or 60VDC are considered "low" voltage and safe to work with.

Currents as low as 20mA if flowing through the human heart can cause defibrillation(cardiac arrest). 100uA can be felt.

Although static electricity charges can build up to several _thousands_ of volts like 10kV, 25kV and even 50kV are common, they are not dangerous because the discharge does not last long and the energy levels are not so high.

AC mains voltage at 120Vrms , 220Vrms or higher at 50/60Hz can be DEADLY.

Capacitors charged up to high voltage such as in a microwave or some TV's can be DEADLY.

High current capability doesnt necessarily mean dangerous if the voltage is low. Example, car battery.

High voltage capability doesnt necessarily mean dangerous if the current is limited and low. Example, static electricity, shock box etc..

Generally, assessing the danger level is not as simple as voltage or current but more about amount of energy delivered and where to and for how long.

To play it safe, stay away from anything over 60VDC.

 

[Joel Rainville]

Daily Planet on Discovery Canada tried an experiment once in a shopping mall. They asked 3 people to hold a mutimeter's leads in each hands, and they took the resistance readings. One was 3.5Mohms, one 7Mohms and the other more than 11Mohms.

They gave a low voltage, low current shock to everyone. First subject with the least resistance had the typical "shock reaction", screamed and couldn't hold to the metallic object for more than a fraction of a second. Second subject at 7Mohms tried to hold on, but she lasted only a couple of seconds and it clearly hurt. Last subject with the most resistance could feel a slight tickle, and had no problem dealing with the "shock". The conclusion was that the thickness of your skin defines your natural resistance to electricity.

Note that this is only relevant with low voltage, low current. Like Optikon said, it only takes a few milliamps through your heart to potentially kill you. I had several 110V shocks when blindly [dis]connecting appliances from the wall, but the current path almost always stayed in my hands. But one time I had a shock through the whole forearm and it ended with what felt like a hammer blow to the elbow, and the circuit breaker tripped. It felt like it lasted a few seconds, but it was probably way a shorter time lapse, more like a few milliseconds. Unfortunately there were no witnesses to confirm :lol: That was quite a feeling :shock:

 

[Styx]

hi friends
plz tell either DC or AC 40 amp current is felt by human body.

40A will not be felt by the body.

Why? because you would be DEAD!!!!!
it takes only 6mA through the brain to kill you.
A bit more in other parts of the body.

The human body has a faily high impedance so to get 40A flowing through some part of the body (say from the hand to the elbow so not to kill straight away) it will take alot of volts

 

[audioguru]

Where are you going to get 40A?

Ohm's Law says that only a few mA will flow through the high resistance of your body, if the voltage is 60V. More current will flow if the voltage is higher.

40A is what the source is capable of supplying to a very low resistance.

 

[Joel Rainville]

Where are you going to get 40A?

Bah, a few millions of volts should do it :lol:

 

[bryan1]

A while ago mythbusters did a test on urining on an electric fence and proved the myth busted but Jamie wasn't standing on wet grass or in water so it had little effect. Yesterday while picking up my son from the bus stop, one of his friends was balling his eyes out so I asked what happened and for a dare he urined on an electric fence but he was standing on wet grass. The hardest part for me was not laughing but I did feel sorry for the young bloke. Anyway that fence has 15,000 volts DC running thru it and NO amps and awhile ago there was a thread on the same subject.

This may seem to be detracting from the thread topic but it does concern DC shocks.


Cheers Bryan

 

[audioguru]

I think your body is like a Diac when high voltage is applied.
The low current burns through your insulating skin, exposing the low resistance of your guts. Then a massive current flows to cook you. :wink:

 

[Klaus]

A while ago mythbusters did a test on urining on an electric fence and proved the myth busted but Jamie wasn't standing on wet grass or in water so it had little effect. Yesterday while picking up my son from the bus stop, one of his friends was balling his eyes out so I asked what happened and for a dare he urined on an electric fence but he was standing on wet grass. The hardest part for me was not laughing but I did feel sorry for the young bloke. Anyway that fence has 15,000 volts DC running thru it and NO amps and awhile ago there was a thread on the same subject.

This may seem to be detracting from the thread topic but it does concern DC shocks.


Cheers Bryan

You cant have 15,000vots and NO amps in a closed circuit, only in an open circuit, like a bird sitting on a single 15,000volt line.
For the young bloke to feel ANYTHING, a current, however small, has to flow to complete a circuit. The magnitude of the current very much depends on the total resistance of the current path.
Now, was that pedantic or what? :wink:
Klaus