[SHOCKING] Protect Your Stuff Against Static Discharge

Category: Hardware

In the past, I have warned readers to beware of static electricity – electrostatic discharge or ESD, in geek speak. 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. That's the low-tech definition of ESD. And maybe that's why I had to eventually make friends with computers. But I digress...

ESD is a high voltage, low amperage electrical current that flows suddenly and briefly between two objects when the make contact or come very close to each other. 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.

Electrostatic discharge

However, electronic components are much smaller and more sensitive to ESD than humans. 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. 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.

Don't Try THIS at Home

Do not attach a wire to your computer’s chassis and then attach the other end to the grounding wire of an electrical outlet, a solution that seems obvious but is actually quite dangerous. AC current flowing through the nearby “hot” wires in the wall can induce an AC current in your grounding wire through electromagnetic induction. That current can flow through your computer to fry you as well as the machine!

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...

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Most recent comments on "[SHOCKING] Protect Your Stuff Against Static Discharge"

Posted by:

Mark Neville
26 Apr 2017

I have seen the micro photographs of the damage ESD can do to IC chips. It is amazing to see the metal and even glass passivation cratered due to a discharge. The metal and passivation melted and beaded around the defect. And the stuff that we were testing was huge compared to technology features of today. I purchased a wrist strap and use it when installing memory or cards in my computer's at home.

Posted by:

26 Apr 2017

You wrote: "Do not attach a wire to your computer’s chassis and then attach the other end to the grounding wire of an electrical outlet, a solution that seems obvious but is actually quite dangerous. AC current flowing through the nearby “hot” wires in the wall can induce an AC current in your grounding wire through electromagnetic induction. That current can flow through your computer to fry you as well as the machine!"

What!?!? Utter hogwash! Every appliance in your home that has a metal chassis -- your fridge, stove, microwave oven, washer, dryer, etc. -- has the ground prong of its plug tied directly to the metal chassis. Why? To *prevent* shocks. If the hot wire becomes frayed or disconnected inside the appliance and shorts to the chassis, the fault current is returned via the ground wire, blowing the circuit breaker. Without this ground connection, the chassis would be live at mains voltage, waiting for you to touch it and be electrocuted.

Connecting a wire from your computer to the ground of an outlet is a silly thing to do, simply because the computer's power supply is already grounded through its power cord, not because doing so creates a shock hazard.

Incidentally, any appliance with a two-prong plug must be double-insulated so that there's no way the hot wire could come in contact with an exposed, conductive part of the device.

Posted by:

26 Apr 2017

Joe, the magnetic fields around the hot and return conductors can induce volts in the ground wire. Ordinarily, the voltage is too low to care about, but there can be brief spikes that can affect tiny components in solid-state electronics.
You might be able to see volts with a voltmeter connected between the grounds on two different receptacles in your house.
In fact, there is what are called "ground loops", in which a conductor grounded at each end is arranged so that it acts as an antenna that can pick up the 60-cycle fields that are everywhere.

Posted by:

26 Apr 2017

Joe: the possibility of an induced voltage is real but it is not at a current level that is hazardous to people.

The other reason for not using a direct wire to it is that you want some resistance do lower the rate of current flow through the device if there is a discharge. It is good practice to always touch the chassis of anything you have open to equalize the charges before touching any component in it.
Serious ESD work areas have conductive work surfaces (grounded via a resistive element) that you connect to with a resistive wrist strap. We have a lab at work that includes a conductive floor and chairs to go along with it. The cleaning crew has to use a special conductive wax on the floor and the chairs have static chains that drag on the floor.

Devices that are not opened up are generally ESD safe unless you touch a conductor on the device. Most outside connected conductors now have protection so that isn't likely to kill things.

I remember a video game in a bar in the '70s that was sensitive to ESD. If you shuffled your feet on the carpet and touched the metal plate on the console, it would reset itself to the beginning of the game. When you were getting close to the end of your lives, a short shuffling walk and you were back playing again.

Posted by:

Stuart Berg
26 Apr 2017

I'm surprised you didn't mention the static shielding bags that most electronic parts come in. The part should be left in the bag until you are ready to install the component.

An interesting story about those anti-static bags: I know someone that mailed an EZPass device back WITHOUT one of those bags (which the device comes in). The device being mailed back picked up some of the tolls on the way back because it wasn't in a bag.

Posted by:

Jay R
26 Apr 2017

Don't the Jetson's have an electron sink for Rosie?

Posted by:

Karl Ferguson
26 Apr 2017

Good Afternoon Bob,

In reference to your "YES... spelling, punctuation etc.etc.are important, please note that you made a boo-boo in the third paragraph of your [Shocking] Static Discharge article. The line "when the make contact" should read as "when they make contact".
Have a great day.


Posted by:

Rick O'Keefe
26 Apr 2017

Y'all might be interested researching or asking for advice on two technical forums concerned with aspects of power quality, lightning and surge protection, lightning safety, and electrical shock medicine:
Lightning/Medicine: http://bit.ly/Lightning_TechForum

Power Quality: http://bit.ly/2p5kWXb

These are not chat sites but are peer reviewed science sites.

Posted by:

27 Apr 2017

I went through 4 hard drives. Tech support was at a loss for over 18 months as to why my hard drives were failing. A customer in line suggested an anti-static desk mat and said while it is controversial as to whether it works, I might want to try it. Low and behold! I haven't had to change a hard drive since. Apparently some people are just more magnetically charged than others. It worked for me. If you having computer issues, you may want to give it a shot.

Posted by:

27 Apr 2017

Fact is it doesn't matter how much voltage is in the component, or you for that matter. All that matters is the potential difference between you and the component. Open the anti-static bag only when you are ready to install the component dropping the potential difference to 0 volts. Then touch a metal part of the case with the component in hand, unplugged since the MB is hot if the power supply has voltage, There will be no ESD.

This is how linemen can get out of a helicopter on a platform hanging from the 180kV line without getting electrocuted. They hook the line with a grounding rod from the helicopter to get everything to 180kV so there is no potential difference.

Posted by:

27 Apr 2017

Good article about ESD. But Bob, I've appreciated your good advice for many years and was "shocked" to read your erroneous comment stating that connecting a wire from chassis to ground is dangerous. It's totally unnecessary, but not dangerous. As others already pointed out, the ground prong on the computer power cord already makes exactly that connection for safety reasons to prevent you from potentially being shocked. Keep up the good work - we'll overlook this one.

Posted by:

27 Apr 2017

Interesting reminder here, Bob.

The employees at my former workplace would kill their fax machines. Being the IT support guy, and being a small company I did telecom as well, so I was called in to see what was happening because there was a ticket regarding a fax machine that kept resetting its self.

After I checked the usual stuff like the power cord and connections, I had one of the users retrieve an order off the machine as I watched to see if there was something wrong with the process or the equipment.

Then sure enough. She got up, walked over to the machine, and the biggest static bolt traveled from her finger to the dial-pad on the poor fax machine! This sent the display into a garbled mess, which cleared when the machine reset. The reset, however, this time didn't help and the machine was now dead with broken circuits.

I explained what the issue was to the boss and the employees and I was laughed at. After ruining another fax machine, the boss purchased some anti-static spray and handed it out to his employees.

Now the issue is not just with people. Please, oh please watch your cats around computers. It's lovely that they sleep on top of the machines and watch bird videos, but if the house is dry a static discharge from their bodies on to the machine can cause damage. I witnessed that with a poor HP laptop a friend wanted me to repair. Her cat used to sleep on the machine when the lid was closed. One day the machine was dead as a doornail, well brick in this case! Nothing, wouldn't boot, etc. The motherboard was fried by Ms. Fluffy as she got up from her nap.

Posted by:

27 Apr 2017

Please pardon me for being pedantic, but I'd like to add to the comments regarding induced currents in ground lines. Yes, ground loops are real, but you'd probably have to run the wire to a ground connection at your neighbor's house down the street to get any significant ground-loop induction (unless you live next door to a machine shop with lots of big motors). The most likely effect of a short local ground loop might be a little hum in your computer's audio circuits. Local ground loops are frequently present through the ground wires in cables between computer, printers, monitors, & other peripherals without any ill effects.

Posted by:

27 Apr 2017

I used to work for Daicel Safety Systems of America (DSSA) in Kentucky. They made the canisters of gas that inflated the airbags in your car or pickup truck in the event of a crash. We had to wear what we called "Static Straps" around our ankles so that we would stay grounded due to the sensitive electronics involved in the manufacturing process. The gas itself is inert (Helium) but the electronics were very sensitive and one errant charge could cause the canister to deploy its gas which could potentially be lethal (flying parts) if one was holding a canister at that time.

Posted by:

27 Apr 2017

Interesting topic for me as I am very susceptible to this static issue, which I have solved with low tech.

I have shocked my computer, heat & A/C thermostat, microwave etc. multiple times, causing the screen to blank. My low tech answer to that is to always touch the outside edge of corners in rooms as I walk around. There is a metal edge under the plaster that keeps me "grounded".

I have a metal / rubber gizmo that I buy from Europe to hang down from my car to the ground. Yes, it works. Before learning of this (which is officially sold to prevent car sickness), I would get a huge shock when I first touched the car.

Posted by:

27 Apr 2017

"Electron Sink" = Where dirty electrons get washed-up!

Posted by:

29 Apr 2017

Years ago I walked across the living room rug in my socks to adjust the TV volume. When i got near the knob with my hand a bright spark flew out to the knob and blew out the volume on the TV! Hurt slightly too

Posted by:

Byron M.
04 May 2017

Having worked many yrs as a construction electrician, I am quite familiar with shocks from induction. Any wire in close proximity to a live wire carrying current can be charged through induction. I have gotten some really bad jolts from bare wires that have been charged through induction. I have a metal pole lamp within arms reach near my computer. Before touching the computer I touch the metal on the lamp. Often getting an audible snap and a tiny shock when I discharge. Often my wife walks past me and touches me while I am working with my computer. We both jump when the static releases from her to me. So having a static strip/bracelet on while working with/on a computer would be a good idea.

Posted by:

Byron M
04 May 2017

Joe, in regards to most appliances having three prong/wire of which one is a ground wire, there are still installations/houses which don't have the third ground wire. I have encountered older rewired/upgraded electrical outlets which have a new grounded outlet installed but the ground wire has not been installed or connected. Either due to cost cutting or a lazy electrician. Other times it is a home owner installation not up to code or safety.
A hazard which many home buyers are not aware of if they don't have a qualified inspector check the electrical installations before purchasing an older home or property.

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