Power plugs and ESD

Discussion in 'General Electronics Chat' started by TomMe, Mar 8, 2013.

  1. TomMe

    Thread Starter New Member

    Mar 8, 2013
    1
    0
    Hi,

    I have a question about something I have been wondering about for while now. I don't know all too much about electronics, but I do know about ESD and that it's not a good idea to handle computer parts without grounding yourself first.

    The question I have is the following. Is it safe for an electronic device to touch the pins of its power plug when that plug is still connected to the device? Like a power cord connected to a computer or TV or a charger connected to a cell phone or tablet. Or is there a chance that this might also produce a static discharge within the device and thus damaging components?

    Thanks!
     
  2. Kingsparks

    Member

    May 17, 2011
    118
    5
    Not sure what you mean. Is the device unplugged? If so then no problem. I don't see how the device could touch the plug unless it is unplugged so I would say it is not a problem.

    Take care.
    Roland
     
  3. MrChips

    Moderator

    Oct 2, 2009
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    Let me rephrase the question.

    Is it safe for someone to touch the prongs of the power plug or could doing so damage the attached device from ESD?

    The answer is yes and no. It depends on the particular device, how the power supply is designed and the sensitivity of the device. In most cases this is not a problem. To be on the safe side, you should discharge your body by touching something that is grounded.
     
    Kingsparks likes this.
  4. takao21203

    Distinguished Member

    Apr 28, 2012
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    Some people can ruin pretty much anything electronic only by looking at it :)

    Bill Gates can light incandescent bulbs only holding them with his hands. OK admittetly urban myth.

    I never use discharge for ESD or grounding, and I use food trays to store controllers and even CPUs directly inside them. MOSFETs, TFT displays, LEDs, logic IC, you name it.

    If however the plastic gives off some kind of static feeling, attracting plastic foil and hairs point up, then stay away from it- the wrong type of plastic. May ruin any kind of chips just by touching it.

    Another thing, believe it or not.
    I had a small plasma ball some years ago.

    I stored a small micro hard drive maybe 1m away from it.
    Shortly after that, it became sluggish, and end of life followed soon. Really about the same day when I had it there.

    OPs question is kind of a joke since if this would be the case, how many appliances are ruined by that each day, month, and year? You name it.

    ESD is not a question of touching something or not. It is a question of ESD prone materials, and ESD containing environments.

    Sparks set up fires in flour mills sometimes and stuff like that. The flour stream can act like a Van de Graaf generator.

    For this reason some cars have rubber bands touching the ground. But in no way every car has these.

    The antistatic wrappings are largely a precaution, and of course for aviation/shipping. There is not really a need to be paranoid about that. Most people can actually touch a Pentium, AMD CPU etc. freely from the pins side- nothing will happen.
     
  5. MrChips

    Moderator

    Oct 2, 2009
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    You can light florescent bulbs by holding them in your hands. This is not a myth.

    ESD is a very serious problem in the electronics industry and is not to be taken lightly.
     
  6. takao21203

    Distinguished Member

    Apr 28, 2012
    3,577
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    Cellophane tape is good for attaching chips to pieces of cardboard, having a cut piece of antistatic bag on the bottom.

    A regular tape could ruin your artwork since it is suspectible to ESD when you pull it off.

    Certain types of cloting, floor coating or even paints, for sure an endless list.

    One day I had a partially latched Pentium.

    After installing a card or changing their position, the board would not boot up anymore. Taking out the Pentium and briefly touching all the pins helped, sometimes repeatedly. Just taking it out and putting it back- to no avail.

    People imagine of a latchup as a flash burning out tracks or puncturing a hole but that is wrong.

    Static can weaken the tiny structures even from a metre distance. It may take a long while with no symptoms.

    Any kind of plastic which attracts dust or tiny paper pieces is a no-no.

    Many plastics today have antistatic agents mixed in actually.

    If you feel a small electric shock from walking over that bad carpet again and touching a chip- it might be too late. Bad carpet in terms of chips survival.

    Or old JFETs- they really had guarding rings.
     
  7. Kingsparks

    Member

    May 17, 2011
    118
    5
    You know, I agree with all these statements.

    I usually wear a grounding strap no matter what I'm working on, electronic wise. But I have handled and touched all sorts of chips, CPU and so on with no ill affect, Not intentionally but by accident and for years I assembled computers, did it after I retired and have yet to have one fail.

    Come to think of it, I can't think of any failure due to my touching a component. I think of the grounding as insurance and no doubt, it can be a problem. I just don't see, from experience, it's that big a problem if you use a bit of common sense.
     
  8. MrChips

    Moderator

    Oct 2, 2009
    12,415
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    Know what, I use a grounding strap and have never witnessed a failure, but that doesn't mean that I don't have to use the grounding strap.

    I take caution when I cross the road and I've never been killed yet.

    I watch what I eat and I have not died from cancer.

    I haven't died from global warming yet.

    Does that mean I don't need to be concerned or that it is not a problem.

    Common sense tells me that it is a big problem. All of the above.
     
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