[ZAPPED!] Don't Get Shocked By ESD
On previous occasions I have warned readers to beware of static electricity (electrostatic discharge or ESD, in geek speak) on their gadgets and computers. Today, I’m going to explain in some detail what ESD is, what it can do to electronic devices, and how protect against this common hazard. Read on...! |
What is Electrostatic Discharge?
I must confess that one of my favorite childhood pranks was shuffling around on a shag rug, and then touching my finger to a friend's earlobe. (And on at least one occasion, my little sister.) That's the low-tech definition of ESD. And maybe that's why I had to eventually make friends with computers (and apologize to my sister). But I digress...
ESD is a high voltage, low amperage electrical current that flows suddenly and briefly between two objects when they make contact or come very close to each other. Yes, it can jump! Voltage is the difference in electrical charge between two points. Amperage is the rate of flow of an electrical current. So an ESD involves a transfer of electrical charge from an object that has a lot of it to one that has much less, but at a relatively slow rate and for a very brief period.
The upshot of an ESD is that its high voltage is literally shocking, but its brevity and low amperage transfer too little electrical energy to seriously harm a human being. But it can produce hilarious YouTube videos like this one .
However, electronic components are much smaller and more sensitive to ESD than human fingers (or earlobes). Tiny transistors, resistors, capacitors, etc., are designed for very precise voltages and amperages. Zap them with an ESD that is wildly outside of their operating parameters and visible holes will be burned in them. Lightning is a very large ESD, and a lightning bolt can start a forest fire.
ESD starts with a buildup of electrons on an object, creating a large voltage (difference in charges) between it and other objects. Typically, rubbing two different materials together will transfer some electrons to one of them. Some materials acquire electrons more easily than others. (Sneakers on a shag rug, for example.)
Are You High Voltage?
Studies have found that a typically clothed human body can build up charges (called “electrostatic potential”) of between 500 and 2,500 volts during a workday - far more than the mere 25 volts it takes to damage electronic components, yet below humans’ perception level. Many plastics, especially Styrofoam, have even higher electrostatic potential. You may have noticed this when breaking down a piece of styrofoam, that the little pieces stick to you. It is recommended to keep disposable coffee cups and other plastic items at least four inches away from electronic devices.
Even rubbing air molecules together rapidly builds up electrostatic potential, which is why blowing or vacuuming dirt out of a keyboard or computer can be hazardous. If you use “canned air,” use a brand made of “anti-static” gases that do not acquire electrons easily.
There is no way to prevent buildups of electrostatic potentials in all the objects, especially people, that come into contact with electronic devices. But we can make the ESD take a path that avoids the sensitive components inside.
People can ground themselves to avoid zapping their electronic devices. Electronics assembly, testing, and repair workers often wear wristbands that keep them constantly grounded via a wire attached to a nearby electron sink. Anti-static floor mats beneath one’s chair come with grounding wires that are attached to electron sinks; they’re a good idea, too.
Touching an "electron sink" before touching an electronic device will discharge your electrostatic potential; it’s a good thing to do each time you sit down at the computer. In practical terms, tapping an object that has a metal chassis and is plugged into a properly grounded outlet should do the trick.
Do Try THIS at Home
Mobile devices that people carry on their persons will gradually acquire the same electrostatic potential that their owners have. An ESD happens only when there is a difference in potentials between objects, as our hapless friend in the video above demonstrates. So you need not worry about the phone in your pocket or the laptop in your shoulder bag.
As mentioned above, the electrostatic potential of the human body is normally imperceptible, even when it discharges. Just because you don’t feel “static shocks” or see little blue sparks is no assurance that you aren’t jolting your computer with enough ESD to damage it. So take precautions even if you don’t see or feel any ESD.
Your thoughts on this topic are welcome. Post your comment or question below...
This article was posted by Bob Rankin on 10 Feb 2022
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Most recent comments on "[ZAPPED!] Don't Get Shocked By ESD"
Posted by:
Ed
10 Feb 2022
Great info Bob. I have always used a wrist band grounded whenever doing anything inside my computer. Lot of people don't realize the potential for damage
Posted by:
Hill
10 Feb 2022
Ed - that was a ggod one - the "potential" for damage.
Posted by:
Mike
10 Feb 2022
Static electricity is more prevalent in dry, winter air. If you keep your humidity levels up there is less likelihood of getting zapped.
Posted by:
Lucy
10 Feb 2022
Yes, as Mike wrote a humidifier helps with dry winter air.
I am so susceptible in the winter that I have to use dryer sheets to wipe my spot on the sofa, and even the 100% wool rug where I place my feet. That helps a LOT.
I have to be careful getting out of the car also, although it is better now we have leather seats.
I "ground" myself before touching even the heating thermostat after I completely fried one. Also before touching any electrical switches. It does become second nature to do it.
Those blue flashes are quite something in a darkened room!
Posted by:
Ernest N. Wilcox Jr.
10 Feb 2022
Any time I open my desktop PCs case to make a change, clean, or for any other reason, I get out my anti-static pad and wrist strap fist. My pad has a second cable that is clipped to the chassis of my case to make sure it gets grounded to the same potential I am after I put on my wrist strap (before I touch anything inside). I don't know if all antistatic pads have this second grounding cable, this is the only one I have ever owned. Fortunately, they don't wear out, at least mine hasn't yet after some thirty years.
I have gone a step further and grounded my power supply unit's chassis to the case's chassis. Since the PSU is grounded to my home's grounding system through the power supply cable, taking this extra step (although probably not necessary) may help to ensure that everything in my desktop's case is grounded (protected), as long as it is mounted to the chassis. I know that anything connected to the PSU is grounded through its wiring system. I also know that anything that uses power gets it from the PSU. It's just that taking this extra step is like taking out insurance against a grounding system failure. My thinking is that if my PSU suffers a short circuit, I cannot know that the PSUs wiring system can/will remain grounded during such an event. I checked my PSUs wiring diagram, and the ground connector in the power connector port/plug is directly connected to the PSUs chassis, as is/are the PSUs wiring system's ground wire(s). By connecting the PSUs chassis to the case's chassis, I provide a second path, external to the PSUs built-in grounding pathway to ground, no matter what happens to the PSU. So, even if the PSUs wiring system's ground wire(s) gets opened (burned/broken connection) during a power surg or some other event, my second path to ground should remain effective, and reduce the likelihood of damage external to the PSU.
In addition, I avoid shuffling my feet. My mom taught me to pick up my feet when I was little. :) The front plate cover mounting screws of any light switch or power plug are grounded to the household grounding system. The threaded ports into which the plate mounting screws are threaded on the switch/power outlet are grounded, so the screws are also grounded. I touch such a screw head before touching any device (my home thermostat, microwave, toaster, etc.) to avoid ESD. I don't know if there is anything more that I can do, but these measures have seemed to work well so far.
Ernie
Posted by:
gene
10 Feb 2022
27 years ago, I fried a motherboard thinking I didn't have any ESD. Never made that mistake again. I do remember playing around electric fences on the farm as a kid, just to see what would happen. Shocking results there too, no beeping though and I didn't have the language yet to express what I felt. Video is very funny - and on point.
Posted by:
Stuart Berg
10 Feb 2022
Bob,
A typo: You wrote "... a transfer of electrical charge from an object that has a lot of it to one that has much less, but at a relatively slow rate ...". I think you meant "... relatively low rate ..." or "... relatively low current ..." because the speed of the electrons isn't affected.
Also, people might want to know that at 50% humidity the ionization potential of air is about 10,000 volts/centimeter or about 25,000 volts/inch. This can be used to roughly determine if an electronic cattle fence device is operating properly by eyeballing the length of the arc that you can see to a ground (not to me).
Stu
Posted by:
Steve Kohn
10 Feb 2022
Bob, either I missed it altogether or you didn't emphasize enough that most ESD damage is NOT visible. The component is damaged internally, but looks perfectly fine from the outside. External examinations aren't worth the time spent on them.
Another problem is that much damage isn't immediate. An internal connection is weakened but still working. It's a few weeks or months later when it stops working "out of the blue" by which time we've forgotten about the earlier careless handling.
Posted by:
Brian B
10 Feb 2022
The bloke in the video is either a great comedian, or a complete idiot. I can't make up my mind which. Why publish something making himself look as stupid as that? Who would listen to what he says when you see that? If you just let the video finish and scroll onto the next one, he's getting zapped again and again in that one too.
When I used to work at an air-ground communication console, I had to use a metal jacketed ball point pen to frequently ground myself, to avoid being zapped every few minutes. Driving through a
steel bridge at speed, produced some interesting results when getting out of the car as well.
Posted by:
Diane
11 Feb 2022
I normally read and enjoy all your articles, Bob, but this one is both alarming and confusing. For the non-technical, non-electricians, among us, can you give some examples of “an object that has a metal chassis and is plugged into a properly grounded outlet”? As I look around my desktop computer, all I have are “electronic components” and they all appear to be made of nothing but plastic.
EDITOR'S NOTE: The back panel of your PC should be metal. Even a lamp should suffice.
Posted by:
liz
11 Feb 2022
I already bought canned air to clean out my computer. I just did a search for this phrase from your article, "“canned air,” use a brand made of “anti-static” gases" and various other combinations of search words, and cannot find anything to help figure out what brands of canned air are safe. It says nothing about that on the can I have. I have to order through the internet and other brands don't mention this either in the info they give there. I did learn, though, that canned air is toxic to the environment and people, but my can says to empty the can before recycling which I don't wish to do because it's toxic. So now I'm afraid to use it for more reasons and can't throw it away! Also learned that it can explode in temps over 120 degrees F. and if I let the garbage folks take it, it could get hotter than that in their vehicle here where I live so it might explode! I know you meant to be helpful and you usually are, but not feeling helped now. *sigh*