+ Post New Thread
Page 1 of 2 12 LastLast
Results 1 to 20 of 23
  1. #1
    Junior Member level 1
    Points: 1,554, Level: 9

    Join Date
    Jan 2005
    Posts
    15
    Helped
    0 / 0
    Points
    1,554
    Level
    9

    What is the maximum DC voltage, that is not lethal?

    What is the maximum DC voltage, that is not lethal?

  2. #2
    Advanced Member level 5
    Points: 160,151, Level: 95
    Awards:
    Downloads

    Join Date
    Oct 2004
    Location
    West Coast
    Posts
    7,943
    Helped
    2302 / 2302
    Points
    160,151
    Level
    95

    dangerous dc voltage

    More specifically, peak voltage greater than 42.4V is hazardous; voltage less than or equal to 42.4V, or SELV (safety extra-low voltage), is non-hazardous. It is difficult to know when electricity can cause serious injury or be fatal. Contact for only 1 to 3sec with currents of only 6 to 200mA can cause electrocution by disrupting the normal rhythm of heart muscles, resulting in fibrillation and leading to death
    Quoted from:
    http://www.ednasia.com/article-7565-...imer-Asia.html
    All varies from person to person .. it is very individual ..

    Regards,
    IanP



  3. #3
    Advanced Member level 3
    Points: 8,525, Level: 22
    rfsystem's Avatar
    Join Date
    Feb 2002
    Location
    Germany
    Posts
    914
    Helped
    142 / 142
    Points
    8,525
    Level
    22

    dc voltage dangerous

    <=60V used for wired phone supply give irritation to most
    <=110V US, shock but mostly not lethal
    220-240V Europe, on the avarage lethal for about a minute

    During the first world war there was a decision to use 220V instead of 110V because then wiring could be a quarter thick. That helps to supply more copper to the battlefield during the first world war.

    Ironical because of this 220V decision more people died by violance on the battlefiled than by electric shock!



  4. #4
    Full Member level 4
    Points: 2,599, Level: 11

    Join Date
    Aug 2006
    Posts
    216
    Helped
    33 / 33
    Points
    2,599
    Level
    11

    lethal voltages

    Very interesting side note - thanks!



    •   Alt16th September 2006, 16:54

      advertising

        
       

  5. #5
    Advanced Member level 5
    Points: 37,801, Level: 47
    flatulent's Avatar
    Join Date
    Jul 2002
    Location
    Middle Earth
    Posts
    4,632
    Helped
    476 / 476
    Points
    37,801
    Level
    47

    minimum lethal voltage

    There is another lethal side effect. The muscle contraction will sometimes cause the person to move, sometimes moving into mechanically dangerous areas and dying from mechanical damage to their bodies.



  6. #6
    Newbie level 6
    Points: 1,352, Level: 8

    Join Date
    Oct 2005
    Posts
    13
    Helped
    0 / 0
    Points
    1,352
    Level
    8

    what dc voltage is dangerous

    Higher DC voltages(over 200V) make blood electrolysys...then very small bubles of gas come into brain...this efect is lethal...human body can be very well and then after 1 or 2 min. :(....otherwords you can smile and think is OK and after
    few min...........
    I work with high DC voltages(600-900) 15 years and I think is more,more dangerous than AC.



  7. #7
    Full Member level 1
    Points: 3,629, Level: 14

    Join Date
    Feb 2002
    Location
    Pakistan
    Posts
    99
    Helped
    3 / 3
    Points
    3,629
    Level
    14

    lethal dc voltage

    for 220 AC, there are chances that one can get away from the wire (which he has touched accidently) because AC's alternating nature - the 50 Hz vibration effect is perhaps the main helpful point of rescue.

    what about 240 DC ? is will there be any chance to get away ? or sudden death ?
    I ask because I am working nowadays with that kind of high DC voltage.



    •   Alt15th July 2009, 19:40

      advertising

        
       

  8. #8
    Advanced Member level 5
    Points: 27,934, Level: 40
    pranam77's Avatar
    Join Date
    Apr 2008
    Location
    Mangalore (INDIA)
    Posts
    2,749
    Helped
    599 / 599
    Points
    27,934
    Level
    40

    fatal dc voltage

    Practically seen, DC is more lethal than AC. It all depends from individual to individual which determines the voltage levels they feel as "lethal". I have one of my close friend Named Rajmohan Nair (Popularely known as "Current Mohan")who is not at all affected by any domestic or industrial electricity. He takes two phases in his two hands and one in the mouth and touches the Neutral with his feet and is still giving shows world wide and is alive.
    A part of his performance may be seen on the link given below.

    http://www.youtube.com/watch?v=PRf9MqqkMDM
    http://my-xperience.blogspot.com/200...uman-body.html



  9. #9
    FvM
    FvM is offline
    Super Moderator
    Points: 170,895, Level: 98
    Awards:
    1st Helpful Member

    Join Date
    Jan 2008
    Location
    Bochum, Germany
    Posts
    27,175
    Helped
    8421 / 8421
    Points
    170,895
    Level
    98

    lethal dc current

    what about 240 DC ? is will there be any chance to get away ? or sudden death ?
    I ask because I am working nowadays with that kind of high DC voltage.
    You're asking the wrong question. You should better ask about the required and optional safety means when working with dangerous voltage levels. Any likelihood of getting away in case of accident must not come true in your individual case.



    •   Alt16th July 2009, 10:30

      advertising

        
       

  10. #10
    Full Member level 1
    Points: 3,629, Level: 14

    Join Date
    Feb 2002
    Location
    Pakistan
    Posts
    99
    Helped
    3 / 3
    Points
    3,629
    Level
    14

    what is the lethal amount of voltage

    Quote Originally Posted by FvM
    You're asking the wrong question. You should better ask about the required and optional safety means when working with dangerous voltage levels. Any likelihood of getting away in case of accident must not come true in your individual case.
    ok, here is, perhaps, the right question

    what should the the safety means in case of working with that kind of high voltages ?
    I have been in germany so i know that in germany there are strict safety regulations. can you suggest me any safety-how-to ?

    For FvM :
    Schlecht Deutsch - Verzeihung.
    Ich hab' im Dortmund etwa 3 Jahren gelebt und war sehr öfter Buchum meinen Kollegen besuchen kommen. Ich hab's gerade gemerkt, unter Dein ID, dass Du aus Bochum bist



  11. #11
    Newbie level 1
    Points: 537, Level: 4

    Join Date
    Dec 2009
    Location
    UK
    Posts
    1
    Helped
    0 / 0
    Points
    537
    Level
    4

    Re: lethal dc voltage

    Hello, does anybody know how much voltage 'Current Mohan' is able to withstand? And how rare it is for someone to be able to act as a conductor for electricity?



  12. #12
    Junior Member level 2
    Points: 616, Level: 5

    Join Date
    Feb 2010
    Location
    new delhi
    Posts
    21
    Helped
    1 / 1
    Points
    616
    Level
    5

    Re: lethal dc voltage

    I seen, DC is more lethal than AC. It all depends from individual to individual which determines the voltage levels they feel as "lethal



  13. #13
    Advanced Member level 5
    Points: 10,728, Level: 24
    WimRFP's Avatar
    Join Date
    Apr 2010
    Location
    Netherlands
    Posts
    1,591
    Helped
    577 / 577
    Points
    10,728
    Level
    24

    lethal dc voltage

    Hello,

    Many standards product standards assume 60Vdc to be safe. For example, look at http://www.ecma-international.org/pu...s/Ecma-287.htm. This one is free and gives good info on safe construction and safe current, voltage and stored charge.

    Also read the assumptions. The safe DC voltage depends, for example, also on the contact surface, moisture and where on your body the contact is (skin resistance varies across your body).

    There is also indirect damage. When you are working above ground, 60V may result in falling down.



  14. #14
    Full Member level 5
    Points: 5,732, Level: 17

    Join Date
    Oct 2005
    Posts
    253
    Helped
    40 / 40
    Points
    5,732
    Level
    17
    Blog Entries
    1

    Re: lethal dc voltage

    I wouldn't mind seeing some comment on working safely with 200-400VDC.

    I am atm fooling around with PC power supplies, and there's rectified AC to DC 340V there.

    I have a isolation transformer, then however earth leakage of that 340V DC I don't believe would trigger the house earth trip switch.
    So far I've just been mindful to be very very careful.....



  15. #15
    Advanced Member level 5
    Points: 10,728, Level: 24
    WimRFP's Avatar
    Join Date
    Apr 2010
    Location
    Netherlands
    Posts
    1,591
    Helped
    577 / 577
    Points
    10,728
    Level
    24

    lethal dc voltage

    Hello,

    An isolation transformer only prevents an electrical circuit (via your body) to ground, but does not protect you from an electrical circuit between two floating wires and your body.

    You can see this (don't try it) when you touch both outputs from your isolation transformer, or the terminals of the capacitors following the mains rectifier in power supply.

    Note that 50 or 60 Hz AC voltage is more lethal (then DC) as is may result in fibrillation of your heart at relative low current levels through your body. This is the reason that many standards mention 42VAC or 60VDC as a safe voltage.



  16. #16
    Junior Member level 3
    Points: 848, Level: 6

    Join Date
    Feb 2009
    Posts
    28
    Helped
    3 / 3
    Points
    848
    Level
    6

    Re: lethal dc voltage

    UL and similar safety standard require a safety interlock for any potential voltage exposures of 42 volts or higher. This comes from the average resistance of a human being with the current levels sufficient to trigger dangerous effects such as fibrillation. When the interlock is enabled (V>=42V), an indicator must light. If enabled and mechanical interlock is broken, the voltage must be shut off regardless of the impact of doing so (destroying devices or equipment).



  17. #17
    Full Member level 5
    Points: 5,732, Level: 17

    Join Date
    Oct 2005
    Posts
    253
    Helped
    40 / 40
    Points
    5,732
    Level
    17
    Blog Entries
    1

    Re: lethal dc voltage

    @jgruszynski
    how does such standard help, when your trying to measure and look at circuits with
    300VDV + and oscilloscope and/or multimeter.
    Finger slip, and ouch high voltage !! i've been careful and no finger slip yet, but what if !!!

    What safety precautions do you use ?



  18. #18
    Full Member level 5
    Points: 1,944, Level: 10
    Sajjadkhan's Avatar
    Join Date
    Sep 2010
    Location
    Rawalpindi,Pakistan
    Posts
    297
    Helped
    17 / 17
    Points
    1,944
    Level
    10

    Re: lethal dc voltage

    Hello,

    An isolation transformer only prevents an electrical circuit (via your body) to ground, but does not protect you from an electrical circuit between two floating wires and your body.

    You can see this (don't try it) when you touch both outputs from your isolation transformer, or the terminals of the capacitors following the mains rectifier in power supply.

    Quote Originally Posted by WimRFP View Post
    Note that 50 or 60 Hz AC voltage is more lethal (then DC) as is may result in fibrillation of your heart at relative low current levels through your body. This is the reason that many standards mention 42VAC or 60VDC as a safe voltage.
    You are totally wrong. An AC can never be as dangerous as DC. AC alternates and at one time it goes through the zero Crossing and this zero crossing is the point where when u accidentally touch the AC wire, u can release ur self.
    Since DC is High all the times, it will never leave u or u cant leave it. that is one of the reason for replacing the main lines from DC to AC.
    And if we talk about current, from Myth Busters on Discovery Channel, they said 4 Amps is lethal for a woman and 5 Amps is lethal for man.
    The thing is what is the voltage level we can comfortably work with? the 60V in telephone line is not lethal but will keep on irritating u by giving bearable shock so obviously u cant work. So voltage greater than 110V which has no current limitation is Hazardous. A 220V-500W inverter can shock u but cant harm u since its current is limited to 500/220 Amps.



  19. #19
    Advanced Member level 5
    Points: 10,728, Level: 24
    WimRFP's Avatar
    Join Date
    Apr 2010
    Location
    Netherlands
    Posts
    1,591
    Helped
    577 / 577
    Points
    10,728
    Level
    24

    Re: What is the maximum DC voltage, that is not lethal?

    Hello Sajjadkhan:

    Finally it is the current and where it goes that determines lethality, even 24Vac can be lethal under special circumstances.

    From "Electrical Safety Handbook 3rd ed, J. Cadick, et al"

    For 60 Hz AC:

    30 mA: Respiratory paralysis, Stoppage of breathing (frequently
    fatal).

    75 mA: Fibrillation threshold 0.5%, Heart action discoordinated (probably
    fatal).

    250 mA: Fibrillation threshold 99.5%
    (≥5-s exposure)

    If fibrillation occurs, even removing the source of current will put you in a very dangerous position without intervention by others.

    For currents >4A, your heart stops during the current passage and will function normally after removal of the source. This is the reason why defibrillation units generate so much voltage to get sufficient current through the heart region.


    Regarding "let go" current:

    1. Victims of DC shock have indicated that they feel greater heating from DC than from
    AC. The reason for this phenomenon is not totally understood; however, it has been
    reported on many occasions.
    2. The DC current “let-go” threshold seems to be higher than the AC “let-go” threshold.

    Info directly from "Electrical Safety Handbook 3rd ed, J. Cadick, et al"

    The danger of DC (even at low levels) is the electrolysis that damages your cells.

    Maybe you should do some investigation yourself also.



  20. #20
    Junior Member level 1
    Points: 1,081, Level: 7

    Join Date
    Feb 2008
    Posts
    16
    Helped
    1 / 1
    Points
    1,081
    Level
    7

    Re: What is the maximum DC voltage, that is not lethal?

    the 60V in telephone line is not lethal but will keep on irritating u by giving bearable shock so obviously u cant work
    On-hook telephone voltage doesn't really give you any shock since no current is being pulled when the phone is in an on-hook condition. Off-hook it's only 30mA-40mA. The real kicker is the 90 to 110VAC from the ring voltage.



+ Post New Thread
Please login
Page 1 of 2 12 LastLast