ESD: Your PC Technician Must Use a Wrist Strap


The next time, before you let a technician lay a hand on your computer, ask that person whether he or she is going to use an anti-ESD wrist strap; walk away with your machine if the answer is ‘No’. Electronics is sensitive to discharges of static electricity (ESD) from tools or human body; shortening the lifetime of an expensive system or frying it because of someone's folly pure negligence or ignorance would be a pity.

I am appalled by the number of people maintaining ESD to be a non-issue: "I installed add-on cards into countless number of computers and never had a problem related to ESD", they say. I encountered shops that offer assembly or installation of parts that were purchased from them or sell complete systems assembled at these shops (often, I was mildly pressed into buying such a service), whose technicians gave me blank mindless stares when I asked about anti-ESD wrist straps.

When challenged, I like to ask such people about hardware that was ‘DOA’ or has failed ‘for no apparent reason’ after functioning for some time. Every one of them seems to have a story to tell. Perhaps, anti-static bags and moisture-absorbing agents found in packaging of most computer parts are ‘marketing gimmicks’ to them, as well as carefully designed and built ESD-protected areas that are found at every serious factory that manufactures electronics, I cannot say.

The tricky, misleading nature of ESD is that, yes, it does not happen every time and, sometimes, when it does happen, its effects may be very subtle and unnoticeable—in the short term. The Hoffmann Group quotes from 70 to 90 percent of faults due to ESD to be latent faults, ones that manifestate themselves only over time, unlike direct faults that can be detected by quality control when a component is manufactured. Another obvious factor that is often overlooked, is the difference of human bodies: while ESD standards and regulations are built around an electrical model of a typical human body, ESD from one person may not happen in the case of another person, even in exactly the same environment (not to mention important conditions that are hard to predict like sweat, cleanliness of hands, skin health, etc.)

What can you do about it? If you never handle computer parts yourself, then, as with many other things in life, do your research, use services of reputable professionals that do not wave off at physics.

If you intend to service computers on your own, however, please educate yourself first. Watch these three videos by a kind man that literally took the pain of measuring conductance while discussing anti-ESD wrist straps and gloves, it is very illustrative (do not be put off by ten seconds in the beginning of the first part, it is quite noisy and loud). Make note of the trick involving touching the computer case that he mentions. This trick should be used only as the last resort, when there is no anti-ESD equipment at your disposal and you are short of time indeed. Because this trick is not the primary subject of his narrative, he omits an important fact that the trick works as intended only if the computer's power supply unit (PSU) is powered off but still connected to grounded mains (if there is grounding at all) or if the case itself is permanently grounded (which not many people seem to do). Since most sane people (correctly) disconnect the power cord from the PSU prior to servicing a computer, thus they also disconnect grounding of the PSU, which may affect the discharge of static electricity from your body, especially if there is a leak of electrical charge between the case and the PSU. Another factor that you should always take into account is the state of grounding connection of the mains—sadly, it may not function as you expect it to. Never assume that there are no electrical faults like this: for best safety, ground yourself independently of any connected circuit. Also, it is important to understand that this trick may cause an ESD only at one point in time and it does not resolve possible accumulation of electrical charge in your body while you work. There are just too many ‘ifs’ for it to be reliable.

The proper, by-the-book way of handling the issue at home is using a regulated antistatic wrist strap (in fact, ESD straps are dime a dozen—there is no plausible excuse for not having a couple in your toolbox; beware, however, of wireless straps—they do not work: wired ESD straps are mandatory for any professional handling electronic hardware). These straps are your cheap insurance, use them by all means.

Carefully choose the object that you connect the strap to: on the Internet, there are plenty of recommendations on doing that ‘right’ by people that perceive electricity to be a force of magic (such as home-made ‘grounding cables’ intended for plugging into the mains et cetera—I prefer to call them ‘self-electrocuting devices’). Besides actually measuring conductance, there is sort of a kosher way of finding such an object: given that you live long enough in the same place, you should know which objects usually ‘zap’ whenever you touch them having accumulated a good measure of static electricity (door knobs, heating water pipes, etc). These objects must have unpainted metal surfaces that are not intended for connection and not connected to a power source of any form (mains, batteries, etc.) in any way whatsoever. For example, in my storage room, I have a free-standing (the floor is ceramic), unpainted rack of metal shelves which always zaps me when I touch it after I pet furry animals or drive a car for prolonged periods of time while wearing synthetic clothes—I connect a wrist strap to that rack whenever I care about ESD.

Having a wrist strap connected, slowly count to five (initial ESD takes a little time)—then you can work. Make sure to reattach the strap if it got disconnected.

Vadim Penzin, August 28th, 2018


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