Why DC shock is more harmful than AC shock?

I have heard that DC shock is more harmful than that of AC shock. Can any one reply me the reason for that.

ac shock grabs dc throws

The answer has been taken from the folowing page:

https://www.allaboutcircuits.com/vol_1/chpt_3/2.html



Direct current (DC), because it moves with continuous motion through a conductor, has the tendency to induce muscular tetanus quite readily. Alternating current (AC), because it alternately reverses direction of motion, provides brief moments of opportunity for an afflicted muscle to relax between alternations. Thus, from the concern of becoming "froze on the circuit," DC is more dangerous than AC.

However, AC's alternating nature has a greater tendency to throw the heart's pacemaker neurons into a condition of fibrillation, whereas DC tends to just make the heart stand still. Once the shock current is halted, a "frozen" heart has a better chance of regaining a normal beat pattern than a fibrillating heart. This is why "defibrillating" equipment used by emergency medics works: the jolt of current supplied by the defibrillator unit is DC, which halts fibrillation and and gives the heart a chance to recover.

do you get stuck or thrown by an ac shock

Thanks for the answer. If anybody else finds any other reason then please post it yah!

body capacitance heartbeat

What I know is that 50Hz current is more dangerous than DC current.However when the frequency increases the effect of the current decreases below that of DC current.You can test it easily with 60V AC and DC.That is,if you are not "superconductive".
I personally almost do not feel 60V DC but 60V AC tickles a little.

which is worse ac or dc for a shock

batdin said:

What I know is that 50Hz current is more dangerous than DC current.However when the frequency increases the effect of the current decreases below that of DC current.You can test it easily with 60V AC and DC.That is,if you are not "superconductive".
I personally almost do not feel 60V DC but 60V AC tickles a little.

Click to expand...

thanks batdin for your comment. As I can remember the skin behaves like a capacitor in parallel with a high-resistance resistor.

Re: DC shock Vs AC shock

With DC you get stuck to the line. Where as AC will throw you off. So with DC you need someone to seperate you with a non conducting material or he too will get stuck.

I hope this non-technical explaination alco helps.

bimbla.

Re: DC shock Vs AC shock

You can try the effect by your self If you catch the telephone line wire tip&ring ; although it's almost 50VDC you will not feel any thing. Then Try to touch the same wire while some one is calling ; The voltage is 75V AC with 25Hz ; You will FEEL the effect !
ofcourse don't try it

Re: DC shock Vs AC shock

how much is the killing voltage by the way? :roll:
are they the same for both dc and ac?

Re: DC shock Vs AC shock

I don't know if this is fully correct, but I've always thought that current is the thing to be afraid of rather than voltage. Don't get me wrong, high voltage is dangerous, but (at least in South Africa) the earth leakage system is set to 18 mA because 30 mA is thought to be fatal. I think that at low voltage, you should still be safe because the body resistance is rather high. But, at higher voltage the current becomes significant, and it possibly does more damage. I've also heard that voltages in the range of about 220 V are more dangerous than higher voltages because they 'grab' you by causing the muscle to contract (especially if you try to clasp a live wire). However, at a much higher voltage (say 525 V), the voltage tends to 'kick you away', but what you need to worry about here is being burnt.

Re: DC shock Vs AC shock

As far as I remember from the lectures on electrical safety (some ten years ago) the skin resistance is not constant with respect to voltage.At low voltages is tens of kiloohms to megaohms depending on condition.
However at high voltages the skin cells that isolate at low voltages are damaged and the body resistance becomes about 1 kohm.With voltage of 220V this quite dangerous.I don't know what time it takes for the resistance to drop to 1 kohm but it is not instantly because I've been "shaken" a lot of times even between my two hands (with 220V) and I am not writing from the afterworld.
The danger depends on the frequency because the heart has its own electrical pulses that interfere with external ones.At high frequencies the body capacitance takes over and most of the currend does not pass through the heart.

Re: DC shock Vs AC shock

Why do we get attached rather stuck when a dc shock is felt but not for ac shock? :wink: :arrow:

Re: DC shock Vs AC shock

well, i THINK it depends on ur own reflects too.. can we like pull back on the very second we feel the shock?
my friend, he got shocked by a 240Vac and he pulled back at once which also caused his whole left arm numbed. i think when the current flow thru more than that, u'll get stucked. Not only DC isnt it? :roll:

Re: DC shock Vs AC shock

i just had a lecture by my proffesor on this topic.

he says it takes very little current to kill an average person. like less than one amp.

however, we can take a lot of voltage (without the amps). of course if the current flows through our heart, then we can say bye bye to ourself.

and he mention that most of the fatal cases of are due to internal burning and not from the electric shock. it is hard to cool our internal cells, and thus we die from internal combustion.

Re: DC shock Vs AC shock

wwfieee said:

and thus we die from internal combustion.

Click to expand...

yeah we die from heating ourselves up.

Actually there is more to it. Two atrias and two ventricles under them are electrically induced muscles in heart. At least as far as we know. In fact myocytes kind of muscle which makes these is electrical impulsed muscle.

Any electrical impulse makes both atrias and ventricles to contract together making heartbeats.


Imagine if existing electrical impulse is added something else in magnitude AC or DC. Heart will fibrillate!



Well under condition of fibrillation it is true heart will beat faster. Will it mean more blood/oxygen pumped???

No! Because the cycle fast isnt a requirement. The amplitude of fibrillation/oscillation or this new heartbeat occurring is very small in compare to full regular heartbeat.

In medical terms this is called "quiver". Heart is quivering. Is beating fast but amplitude of beating is very small and amount of oxygen/blood is about at least 20 times less then regular heart beat.

There are people who had fibrillation/quivering of 500 (500/60=8.3 Hz frequency) heartbeats per min. Regular heartbeat is between 60-90 (1-1.5 Hz) under normal state.


It is "shocking" why so fast heartbeating so little blood/oxygen is pumped. There is condition of "heating ourselves up" because we have resistance.

Adding up complications addition of electrical current (ac or dc) is creating to our electrical system body OF COURSE does not get any better but worse.

Kids do not play with electricity! Santa-Clauss will not bring you presents for Christmas because he will be mad.

djalli

Re: DC shock Vs AC shock

I could not understand well from the above discussion about getting stuck and thrown off in different cases of shock. Can any one explain me that in detail friends?

Thank you.

DC shock Vs AC shock

I shocked myself with 220VAC 50Hz. I was about to plug in my UPS because the battery was running low and it was still in operation! My index finger (I can't rememeber if it was right or left, I think right) accidentally touched the plug pins and I zapped my finger. I wasn't painful, just felt like someone was giving it a good squeeze.

Plus, if you have excess iron in your blood, this will increase the conductivity and so reducing the heating effect, not so?

Sputnik :idea:

Re: DC shock Vs AC shock

So, if there is more amount of iron in our blood, does it mean that the effect will be less due to less heating effect or will the effect be more due to more conductivity?
thank you

Re: DC shock Vs AC shock

I don't think the variation of iron content will change the body conductance by much. I doubt if iron content in blood varies very widely and anyway the iron content in blood is about 1-2 milligrams/litre.
However even if iron content increases and conductivity increases this will increase the current flow through the body and will be more harmful despite the reduction in heat dissipated.

Re: DC shock Vs AC shock

OK you techno geeks the question is ac vs dc,i've been hit by both and from my standpoint ac is more lethal than dc.Whoever says that ac jolts you off is full of sh--.Every person i've talked to says just the opposite along with your local fire dept.It won't let you go.If dc is that much more potent than why doesn't the industry use it?It seems to me that the more powerful motors and equipment in the real world uses ac for the fact that it produces more power and then there's the economical factor also.I don't see alot of 10,000 volt dc wires hanging over my head on a daily basis.Just food for thought.Prove me wrong,please.