| Author |
Message |
anishjp
Joined: 04 Jan 2008
Posts: 58
Helped: 1
Location: "Gods own country".. Kerala
|
 03 Aug 2008 18:10 Which one is more danger AC or DC...? |
|
|
|
Hi,
Out of AC and DC, which one is more dangerous (receiving an accidental shock) to human life..? , and Why...
|
|
| Back to top |
|
 |
KoRGeNeRaL
Joined: 08 Mar 2006
Posts: 72
Helped: 5
Location: Turkey
|
| 03 Aug 2008 21:04 Re: Which one is more danger AC or DC...? |
|
|
|
It wouldn't be right to say something like AC is more dangerous than DC or vice versa. Both are dangerous but their effects changes with the voltage level, frequency and of course the device in which they're used.
If the path of the current flow doesn't contain your heart, the current needed to give you ventricular fibrillation is less compared to DC when AC is in question. AC frequency is another factor, a high frequency AC signal would burn you rather than leading to fibrillation and death.
On the other hand, DC is more likely to stop your heart because it won't allow your muscles to move away from whatever that was giving you the shock.
Also generally the risk of electric shock is higher in AC systems if grid connected systems are in question, due to the fact that the power system is earthed and the only thing that should be done to have an electric shock is touching to a single live wire.
Regards.
Last edited by KoRGeNeRaL on 20 Aug 2008 21:52; edited 1 time in total |
|
| Back to top |
|
|
Externet
Joined: 29 Jan 2004
Posts: 58
Helped: 2
|
| 03 Aug 2008 21:06 Re: Which one is more danger AC or DC...? |
|
|
|
I would say alternating current is more dangerous.
Because 50V DC is 50 V. 50V AC is actually 140 V peak to peak.
|
|
| Back to top |
|
|
joozwa
Joined: 31 May 2008
Posts: 11
Location: Poland
|
| 06 Aug 2008 8:31 Which one is more danger AC or DC...? |
|
|
|
| It's rather difficult question. I would say that DC may be more dangerous because of the effects of the electrolysis that are much more noticeable than in case of AC.
|
|
| Back to top |
|
|
a_tek7
Joined: 09 Feb 2006
Posts: 345
Helped: 12
Location: Bandar Abbas
|
| 07 Aug 2008 1:13 Re: Which one is more danger AC or DC...? |
|
|
|
| current is important too.250ma can be dangerous.
|
|
| Back to top |
|
|
madicalphy
Joined: 22 Jul 2007
Posts: 35
Helped: 3
|
| 07 Aug 2008 6:00 Re: Which one is more danger AC or DC...? |
|
|
|
DC volatge with high current source can be more dangrous, even 50v with 20A is a big source.
so i think votage less than 100 but with high current source are dangrous rather high volatge but low current.
what you people say?
|
|
| Back to top |
|
|
xulfee
Joined: 27 May 2008
Posts: 256
Helped: 25
Location: Pakistan
|
| 07 Aug 2008 7:50 Which one is more danger AC or DC...? |
|
|
|
| Ac is more dangerous
|
|
| Back to top |
|
|
sushain
Joined: 15 May 2007
Posts: 4
|
| 07 Aug 2008 9:10 Re: Which one is more danger AC or DC...? |
|
|
|
| if the voltage level of both are same then DC is more dangerous than AC. Shocks due to DC are much more fatal due because of its constant supply whereaes AC regularly crosses zero because of its pulsating nature
|
|
| Back to top |
|
|
umery2k75
Joined: 19 Apr 2006
Posts: 258
Helped: 19
|
| 07 Aug 2008 9:21 Re: Which one is more danger AC or DC...? |
|
|
|
Why don't electric welders get electrocuted that easily? They use very heavy source of current. We don't see cases of electric welder getting electrocuted.
I think they use very low AC voltage and very high current. There must be a factor by which they don't get electrocuted.If I happen to find a welder shop in my way, I would go and ask what's the voltage and current, those guys use for electric welding.
|
|
| Back to top |
|
|
Awarapunshee
Joined: 11 Jul 2007
Posts: 356
Helped: 48
|
| 07 Aug 2008 10:14 Re: Which one is more danger AC or DC...? |
|
|
|
| Actually it is current that creates problem. But there is enough potential required to flow that much amount of current between two points (of a body etc). Thats why some body receieves shocks even at 60V AC some don't, because of the different body resistance. The minimum amount of current that prove fatal would be a question to discuss. I read some where in a book that there is a letgo current which is 0.8mA to 1mA (I do not remember where I read so I cannot confirm this)
|
|
| Back to top |
|
|
Jack// ani
Joined: 02 Dec 2004
Posts: 459
Helped: 23
|
| 07 Aug 2008 17:49 Re: Which one is more danger AC or DC...? |
|
|
|
| umery2k75 wrote: |
Why don't electric welders get electrocuted that easily? They use very heavy source of current. We don't see cases of electric welder getting electrocuted.
I think they use very low AC voltage and very high current. There must be a factor by which they don't get electrocuted.If I happen to find a welder shop in my way, I would go and ask what's the voltage and current, those guys use for electric welding. |
Yes, that's right, those electric arc welding usually operates low voltage ranging from 20-30V, however, current is quite high 20-100Amps which is adjustable as per welding requirements.
You get electrocuted for voltages usually above 50 volts, that very well explains why electric arc welders don't get electrocuted!
However, you can still get fatal shock if wounded/bleeding part of body is exposed to these low voltages 
|
|
| Back to top |
|
|
-jps-
Joined: 03 Jan 2008
Posts: 23
|
| 08 Aug 2008 11:10 Re: Which one is more danger AC or DC...? |
|
|
|
| voltage is not dangerous but the current the flow within a conductor is so dangerous
|
|
| Back to top |
|
|
MickDDnt
Joined: 08 Aug 2008
Posts: 1
|
| 08 Aug 2008 13:49 Re: Which one is more danger AC or DC...? |
|
|
|
There are too many variables to give a straight AC or DC answer. Going back to basics V=I x R. It is usually a Voltage that you will come in contact with that will cause a Current to flow thru your body. The Resistance of your body will determine how much current will flow thru your body. This will depend on many factors - skin resistance, sweat, wet fingers, rubber boots, wet floor etc.
Remember it only takes 6mA through your heart to kill you. That is why many old timers will put their left hand in their pocket when fiddling inside live equipment. The natural reaction is to grab the chassis with your left hand and poke around with your right hand. If you get a shock the current will run up your right hand across your chest (thru your heart) and exit to the chassis via your left hand. Put your hand in your pocket and the current must find another path.
Some say that DC shocks are worse because your muscules cramp up where as AC tends to make them convulse. As a result DC is more likely to make you hang on where as AC is more likely to throw you off. Again that is why old timers tend to touch a potentially live part (for example an electric fence) with the back of the hand so that a shock will cause the hand to be moved away where as if you touch it with the open palm there is more chance of grabing the live item.
Some also say that 110VAC is more dangerous than 240VAC because 240VAC is more likely to kick you off than 110VAC. I suggest that you try to avoid both and AC and DC!!!
Added after 18 minutes:
An electric welder can have an open circuit voltage up to about 100v between the electrode and work terminals. It is not unusal for welders to get a shock - especially when changing rods. Again there are many variables - sweaty body because of the PPE they are wearing, wet gloves, wet conditions etc.
Many welders are now fitted with VRD's - Voltage Reduction Devices to reduce the chance of electric shocks. VRD's sense that the Welder is not welding and limit the open circuit voltage to 20-30 Volts.
Some Welders don't like VRD's as they say that the VRD makes it harder to stike an arc because of the delay caused by the VRD sensing that the Welder is actually welding and allowing full voltage to appear at the terminals.
|
|
| Back to top |
|
|
hkBattousai
Joined: 16 Jun 2007
Posts: 86
Helped: 4
Location: Turkey
|
| 09 Aug 2008 5:28 Re: Which one is more danger AC or DC...? |
|
|
|
| anishjp wrote: |
Hi,
Out of AC and DC, which one is more dangerous (receiving an accidental shock) to human life..?, and Why... |
It is simple.
Design an electrical circuit representing your body, and calculate whether AC or DC dissipates more energy in.
|
|
| Back to top |
|
|
kiprono
Joined: 18 Nov 2005
Posts: 243
Helped: 15
Location: Nairobi
|
| 09 Aug 2008 7:43 Re: Which one is more danger AC or DC...? |
|
|
|
| A DC of at least 30V is enough to kill. Remember dc hits you without a break. AC at least passes through zero!
|
|
| Back to top |
|
|
hkBattousai
Joined: 16 Jun 2007
Posts: 86
Helped: 4
Location: Turkey
|
| 09 Aug 2008 8:07 Re: Which one is more danger AC or DC...? |
|
|
|
| kiprono wrote: |
| A DC of at least 30V is enough to kill. Remember dc hits you without a break. AC at least passes through zero! |
Passing through zero may mean a worst case depending on the circuit we talk about.
How much do you know about human body? Maybe there are some kind of body sections which behave capacitive. They will be sensitive to the "passing-zero" regions of the input voltage.
You must know the circuit structure very well in order to talk about which wave form harms more.
|
|
| Back to top |
|
|
Awarapunshee
Joined: 11 Jul 2007
Posts: 356
Helped: 48
|
| 09 Aug 2008 8:58 Re: Which one is more danger AC or DC...? |
|
|
|
| kiprono wrote: |
| A DC of at least 30V is enough to kill. Remember dc hits you without a break. AC at least passes through zero! |
I don't agree. In reality it is not possible. I did not hear that any body die with 30VDC...However 60V or more than that may be a figure. I had work on 48VDC 100A output power supply and I touched both terminal many times. See I am alive.
|
|
| Back to top |
|
|
hkBattousai
Joined: 16 Jun 2007
Posts: 86
Helped: 4
Location: Turkey
|
| 09 Aug 2008 9:12 Re: Which one is more danger AC or DC...? |
|
|
|
| Awarapunshee wrote: |
| kiprono wrote: |
| A DC of at least 30V is enough to kill. Remember dc hits you without a break. AC at least passes through zero! |
I don't agree. In reality it is not possible. I did not hear that any body die with 30VDC...However 60V or more than that may be a figure. I had work on 48VDC 100A output power supply and I touched both terminal many times. See I am alive. |
Once I built a voltage multiplier circuit. Output voltage was about 65VDC. I touched both terminals (while voltmeter was connected and still reading 65VDC) and didn't even feel anything.
|
|
| Back to top |
|
|
Awarapunshee
Joined: 11 Jul 2007
Posts: 356
Helped: 48
|
| 09 Aug 2008 9:48 Re: Which one is more danger AC or DC...? |
|
|
|
| hkBattousai.....Yes you are right it all depends on the body and its condition also. But one should be careful with the voltages higher than 60V.
|
|
| Back to top |
|
|
breneer
Joined: 06 Sep 2004
Posts: 49
|
| 15 Aug 2008 14:32 Re: Which one is more danger AC or DC...? |
|
|
|
| voltages are dangerous because of the current..
|
|
| Back to top |
|
|
kiprono
Joined: 18 Nov 2005
Posts: 243
Helped: 15
Location: Nairobi
|
| 16 Aug 2008 21:30 Re: Which one is more danger AC or DC...? |
|
|
|
| Ultimately, all depends on the resistance offered by your body to current flow.
|
|
| Back to top |
|
|
kender
Joined: 19 Jun 2005
Posts: 965
Helped: 70
Location: Stanford, SF Bay Peninsula, California, Earth, Solar System, Milky Way
|
| 17 Aug 2008 4:18 Re: Which one is more danger AC or DC...? |
|
|
|
| KoRGeNeRaL wrote: |
| A high frequency AC signal would burn you rather than leading to fibrillation and death. |
This effect is used for tissue ablation by medical devices. The frequency is usually 400-500kHz. The subject gets a warmth/heat/burn sensation, but there's no "electric shock" sensation and no muscle twitch. I've tested it on myself by touching the electrodes of a running device.
|
|
| Back to top |
|
|
hkBattousai
Joined: 16 Jun 2007
Posts: 86
Helped: 4
Location: Turkey
|
| 17 Aug 2008 6:39 Re: Which one is more danger AC or DC...? |
|
|
|
| kender wrote: |
| KoRGeNeRaL wrote: |
| A high frequency AC signal would burn you rather than leading to fibrillation and death. |
This effect is used for tissue ablation by medical devices. The frequency is usually 400-500kHz. The subject gets a warmth/heat/burn sensation, but there's no "electric shock" sensation and no muscle twitch. I've tested it on myself by touching the electrodes of a running device. |
Intresting. I didn't know about this. Why does high frequencies do such an effect, do you know the explanation? Maybe the nerve cells are behaving capacitive, and drain more energy at higer frequencies. Or the overall body drain more energy and get warmer.
|
|
| Back to top |
|
|
kender
Joined: 19 Jun 2005
Posts: 965
Helped: 70
Location: Stanford, SF Bay Peninsula, California, Earth, Solar System, Milky Way
|
| 18 Aug 2008 3:31 Re: Which one is more danger AC or DC...? |
|
|
|
| hkBattousai wrote: |
| kender wrote: |
| KoRGeNeRaL wrote: |
| A high frequency AC signal would burn you rather than leading to fibrillation and death. |
This effect is used for tissue ablation by medical devices. The frequency is usually 400-500kHz. The subject gets a warmth/heat/burn sensation, but there's no "electric shock" sensation and no muscle twitch. I've tested it on myself by touching the electrodes of a running device. |
Why does high frequencies do such an effect, do you know the explanation? |
Here's my crude understanding*. Electric voltage depolarizes the neuron. For the neuron to "fire", it should stay depolarized for some finite amount if time. In case of high frequency AC (100kHz and above), the neurone doesn't stay depolarized long enough to fire.
I've also heard that the tissue has weak rectifying properties, so the applied AC can get rectified, and a DC component will develop. I haven't seen that myself yet.
-------
* I'll verify and update this in the next couple of days.
Last edited by kender on 18 Aug 2008 16:27; edited 1 time in total |
|
| Back to top |
|
|
SWINI
Joined: 19 Mar 2007
Posts: 48
Helped: 2
|
| 18 Aug 2008 10:36 Which one is more danger AC or DC...? |
|
|
|
AC is more dangerous as it carries more power compared to
dc circuit..
|
|
| Back to top |
|
|
hkBattousai
Joined: 16 Jun 2007
Posts: 86
Helped: 4
Location: Turkey
|
| 18 Aug 2008 11:43 Re: Which one is more danger AC or DC...? |
|
|
|
| kender wrote: |
Here's my crude understanding*. Electric voltage depolarizes the neuron. For the neuron to "fire", it should stay depolarized for some finite amount if time. In case of high frequency AC (100kHz and above), the neurone doesn't stay depolarized long enough to fire.
I've also heard that the tissue has weak rectifying properties, so the applied AC can get rectified, and a DC component will developped. I haven't seen that myself yet.
-------
* I'll verify and update this in the next couple of days. |
This is an important detail. We should have some biomedical knowledge to talk about this, don't we?
And yes, "feeling warm" and "getting warm" are different things. Electric energy will effect neurons as well.
|
|
| Back to top |
|
|
insrusingh
Joined: 08 Jul 2008
Posts: 16
|
| 20 Aug 2008 5:26 Which one is more danger AC or DC...? |
|
|
|
| It is correct thet DC is more dangerous(much more dangerous than AC).Because if you get a shock from DC suppose 200V,100A then you will die but if that is AC it is pulsating so there is chance that you will be saved.
|
|
| Back to top |
|
|
xaccto
Joined: 30 Oct 2005
Posts: 16
|
| 08 Nov 2008 9:54 Re: Which one is more danger AC or DC...? |
|
|
|
| lol, this topic got me wondering now, is the electric "chair" AC or DC to deliver the fatal stuff?
|
|
| Back to top |
|
|
hkBattousai
Joined: 16 Jun 2007
Posts: 86
Helped: 4
Location: Turkey
|
| 08 Nov 2008 10:10 Re: Which one is more danger AC or DC...? |
|
|
|
| insrusingh wrote: |
| It is correct thet DC is more dangerous(much more dangerous than AC).Because if you get a shock from DC suppose 200V,100A then you will die but if that is AC it is pulsating so there is chance that you will be saved. |
Tell us, just what makes you think that a pulsating voltage is less dangerous that DC voltage?
And if a human body lets 100A through for a 200V DC voltage, its ohmic resistance must be 2Ω.
(Being more precise, V(s) = I(s) . Z(s), where |Z(s)| = 2 for jw = 0)
Just what kind of a body could have such a low resistance? Do you consider humans same as fish or earth worms?
As I told above, don't gas out without knowledge in human biology, chemistry and circuit thoery.
|
|
| Back to top |
|
|
kender
Joined: 19 Jun 2005
Posts: 965
Helped: 70
Location: Stanford, SF Bay Peninsula, California, Earth, Solar System, Milky Way
|
| 08 Nov 2008 10:28 Re: Which one is more danger AC or DC...? |
|
|
|
| xaccto wrote: |
| lol, this topic got me wondering now, is the electric "chair" AC or DC to deliver the fatal stuff? |
Historically, the "chair" is AC. At the turn of a century in the beginngin of the electric era there was a cut-throat competition between Westinghouse and Edison. Westinghouse was pushing the AC, Edison was pushing the DC. At the same time, both of them had proposed a design of an electric chair to the government. Edison yielded the contract to Westinghouse. Westinghouse had built AC "chairs", but he got a lot of negative publicity. Immediately, Edison started a campaign claiming that AC is unsafe.
Last edited by kender on 13 Nov 2008 20:24; edited 1 time in total |
|
| Back to top |
|
|
