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Can any one tell me which is more danger: AC or DC?

It all depends on the voltage. :^) But AC is held to be more likely to stop your heart and DC is held to give a stronger "can't let go" factor. Under the wrong circumstances, either will ruin your whole day.

Regards

cww

That's current flow what kills and if it's high enough it really doesn't matter if it's DC or AC. However, if one happen to survive the shock itself then DC is more dangerous. It's because DC current does elecrolysis of body fluids and products of it are toxic. So it may happen that few hours after shock one dies because of poisoning.

Regards,

Jacek Dobrowolski

DC is more dangerous than AC. Because, AC varies from zero to maximum and then again to zero..In this way, AC puts jerks to a person due to continuous variations. On the other hand, DC is smooth, unvariable and continuous.

DC is more dangerous than AC. Because, AC varies from zero to maximum and then again to zero..In this way, AC puts jerks to a person due to continuous variations. On the other hand, DC is smooth, unvariable and continuous.

Both are equally lethal, it is like asking what causes the worst death, a truck hitting you or a car, either way you die !

AC in theory would allow your muscles time to be able to move so that you could pull your hand / limb away from whatever it was that was giving you the shock. DC on the other hand is supposed to prevent this from happening.

I have had a few shocks in my time from both AC and DC and would strongly recommned NEVER getting them and designing systems to prevent them ever happening.

It has made me a super safety person and as a result i do not recieve shocks anymore.

Either way AC/DC are both more than capable of killing you.

There have been several suggestions that an AC shock will allow enough time for your muscles to relax to release the conductor. This of course is false, as the zero crossing time is only a few milli-seconds at most.

If you are receiving an AC shock, you might be able to pull your hand from the conductor (or pull the conductor from your hand) using muscles which are not in the current path. You will definitely not however be able to relax those muscles which are contracted by the electric current.

I was subjected to a non-job related accidental electric shock (someone had repaired an outdoor extension cord with electrical tape) which passed from my hand to my feet, and can assure you that you have no voluntary control over muscles which are subjected to an AC shock.

dc is the most dangerous as it isn't alternating from positive to negative which gives you a release if you grip an AC POWER source. DC will grip you as your nerves clench and feel uncontrollable

The cyclical rate that A/C operates at will not allow a "lax time" enough for you to let go. a 110 V household circuit will kill you deader than a doornail. A 220V will do it twice as fast.

When electricity was in its infancy there was a battle between Edison and Westinghouse as to which would be the standard, AC-Edison or DC-Westinghouse. Since the electric chair was becoming the preferred method of executing people and the electric chair used AC, Westinghouse used that as a campaign against Edison to show people the killing power of AC. Of cousrse as we all know today, AC became the standard in all of our houses today. Hope that helps.

Actually true, except AC Westinghouse and DC Edison. AC won out because of the ease of transmission whereas DC would have to be produced locally. Now they are figuring out the actual overall efficiency and it strongly favors local generation, though not DC.

Regards
cww

Actually you have it backwards...Edison was championing DC, Westinghouse AC, because he was unable to break Edison's patents.

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Just to clarify the Edison-Westinghouse's tale:

1) Edison used and promoted the usage of DC and not AC. Even, the war against AC led Edison to development and promotion of the electric chair as a demonstration of lethal AC versus his "safer" DC.

As part of this promotion, Edison publicly electrocuted dogs, cats, and is considered the intellectual killer of Topsy, the Luna Park's elephant (have you ever seen that "ugly" movie?).

2) Edison and Westinghouse had a common friend called Telsa who worked for Edison first and later for Westinghouse when Edison did not understand/approve his improvements and investigations to improve electric power distribution (stuff that Westinghouse accepted with his arms wide open).

Also, Edison did not pay him the offer of $50,000 if Tesla was able to redesign of Edison's DC generators. Tesla did the task very well and Edison replied to him with the famous statement: "Tesla, you don't understand our American humor!"

The rest is history!

Best regards.

Saludos.

Gustavo A. Valero P.
BIConsulting C.A.
Valencia - Venezuela
gustavo.valero@biconsulting.com

Which is more useful -- sugar or salt?

Check:
http://www.epanorama.net/links/safety.html#safety

AC or DC?
It's depends on where it going to be used.

AC could be dangerous to human being, otherwise some devices more save if work with AC.

DC harmless and appropriate for small powered devices, but some devices could endanger overall system if using this DC.

So, word "Danger" is confusing . . . need some preparations and analysis for design.

Danger is relative. Assuming you meant danger to human life, then both AC or DC currents are dangerous, provided that the magnitude of currents involved are deadly to humans. A DC current as low as 100 mA is capable of stopping the heart, if injected directly to the heart. That is why in instrumentation, 4-20 mA is the selected current range for analog signals, which means you can touch a live signal cable without danger. Of course, there are other instances when one is more dangerous than the other. For example, AC currents can induce voltages on dead adjacent cables, while a DC does not. You think that a circuit has been isolated already, but think again. To be on the safe side, consider them both as dangerous.

Cybernaut

The below websites provides discussion AC/DC during shock and it can be seen that it takes on average a higher level of DC to provide the same effect as AC.

http://www.allaboutcircuits.com/vol_1/chpt_3/4.html<http ://www.allaboutcircuits.com/vol_1/chpt_3/4.html>
http://www.merck.c om/mrkshared/mmanual/section20/chapter277/277a.jsp<http://www.merck.co m/mrkshared/mmanual/section20/chapter277/277a.jsp>

There is some good material on this subject in Appendix "B" of Lawrence Livermore National Laboratory EH&S manual at:
http://www.llnl.gov/es_and_h/hsm/doc_16.01/doc16-01.html<htt p://www.llnl.gov/es_and_h/hsm/doc_16.01/doc16-01.html>

Some other web sites of interest on this subject:

http://www.ecmweb.com/ar/electric_basics_electric_shoc k/<http://www.ecmweb.com/ar/electric_basics_electric_shock/>

http://www.eet.unsw.edu.au/staffweb/ohs/Safety%20Manual_UG-200 5.pdf<http://www.eet.unsw.edu.au/staffweb/ohs/Safety%20Manual_UG-2005. pdf>

A book which contains some good material on this subject:

"Electrical Instruments in Hazardous Areas, 4th Ed," Ernest Magison, ISA, ISBN: 1-55617-638-4

Several posters have correctly pointed out that both can seriously injure or kill you so if dangerous DC or AC voltage levels are present, it is doubtful that making engineering or administrative judgments on which is safer will result in safe practice.

Bill Mostia
WLM Engineering

Both are dangerous if they were high voltages, for example more than 12V.

AC is more dangerous since it deals with the amps. I've seen someone get hit by a 1000 Volts in a presentation. But only with 1mA a person can get killed.

It's good that people are showing they know the real facts about the history of Tesla and Edison. Edison was a monumental jerk and more businessman than a real scientist. Even today, his shotgun method of experimentation is called 'Edisonian' as a derogatory term by modern scientists.

Tesla was only one person whose ideas Edison robbed. Frankly it's appalling Edison has such a reputation as a 'great inventor'. It was the mobs of people working for Edison that gave him his success which he never shared.

But at least Tesla got the last laugh. And we're reminded of that every time we turn on a light.

You guys should read about Tesla first. Edison was promoting DC and made sure the electric chair was AC to scare people away from AC. He would electrocute animals on stage to demonstrate the danger of AC. "Tesla, a man out of time" is a must read for anyone working with electricity.

Pasted from a website about Tesla:
"Arriving in New York City with four cents in his pocket, Tesla found employment with Thomas Edison in New Jersey. Differences in style between the two men soon led to their separation. In 1885, George Westinghouse, founder of the Westinghouse Electric Company, bought patent rights to Tesla's system of alternating-current. The advantages of alternating-current over Edison's system of direct-current became apparent when Westinghouse successfully used Tesla's system to light the World Columbian Exposition at Chicago in 1893."

Westinghouse was also a prolific inventor, to this day most railways still use the Westinghouse brake system.

Roy

Reading this I'm reminded of another danger: A hundered years after the Westinghouse company was founded it was run into the ground by top management handing the control to finacial managers who never learned what it was they were in business for. It was lost in half a decade...

Hugo

Don't you just hate it when those Amps sound off without any Volts to back them up?

The most dangerous is known as the COLUMB EFFECT. This is when the power passes between the two hands, across the chest and thru the heart. This is the real killer.

You need to ask the question, "To current, are people more resistive or reactive?" The question will lead you to your answer.

"To current, are people more resistive or
reactive?"

Definitely more reactive. I remember as an apprentice giving one of the journeymen a shock with the 500 V megger. He "Reacted" by giving me a belt over the ear.

Roy