ESD in my specific situation - Page 1
Forum section: electronics / repair

author: watchmaker
author_rank: Unknown
timestamp: December 11, 2023, 04:37:49 pm
content: I have a temporary station in the basement which has a layout I will use when I build my permanent one (U-shaped with 4' work bench and TE on shelves above, sides for books and laptop, etc).When I first set it up, I got tickled when I touched a chassis of a meter. I measured the voltage at 47 VAC. Traced it to a molded head on an extension I was using to supply my then inadequate setup. Broken earth pin SOCKET! Cut off the head and sent it to the dump. The voltage was the same between the chassis and my concrete floor.Fixed it.I just bought a Bertech mat kit for my MDF work area. I do not wear synthetic clothes. I have handled MOSFETs with no damage.Been reading about ESD and floors/shoes. I tend to wear rubber soled shoes. Also, the basement humidity never gets below 45% even though we run a dehumidifier in summer to protect storage. The whole basement is below grade.I know concrete grounding can change. I am concentrating on through hole (jelly bean?) devices for the foreseeable future, although ICs will likely creep in.Given my description, is there a compelling reason to consider floor/shoe grounding and such? A mat in front of my chair is cheap, but it is one more thing to keep clean and damage.

author: Ian.M
author_rank: Super Contributor
timestamp: December 11, 2023, 08:18:08 pm
content: If you ever work on mains or high voltage equipment, a below grade concrete floor is a safety hazard, as its conductivity significantly increases the risk that any shock you may get will stop your heart. Insulating (or ESD dissipative) floor covering for at least 6' around the bench mitigates the risk.Some discrete semiconductors are *more* ESD sensitive than most ICs. If you know you are working with highly ESD sensitive (or less ESD sensitive but expensive) parts, its only common sense to use a wrist strap. As a hobbyist, paying for one's own mistakes, its easier to maintain adequate ESD prevention procedures when necessary, than it is to enforce good ESD management for all staff in a factory environment - as for most of the staff its just another annoyance they have to put up with to collect their pay cheque, hence the general preference for ESD dissipative flooring and heel straps etc. over, or in addition to, wrist straps anywhere management cares about ESD prevention, and testing its effective, rather than paying lip service to ESD prevention standards!For those paying lip service to ESD prevention, there is a whole industry dedicated to parting fools from their money. Placebo effect is only beneficial for human health - the boards and components neither know nor care what ESD 'theatre' (mis)management is conducting. e.g. see:https://sma.nasa.gov/news/articles/newsitem/2018/01/10/esd-wireless-wrist-straps-the-shocking-truth

author: watchmaker
author_rank: Unknown
timestamp: December 11, 2023, 09:44:43 pm
content: Quote from: Ian.M on December 11, 2023, 08:18:08 pmThanks Ian. I did watch Dave's mythbuster on the wireless straps just for fun yesterday. I figured they were pretty worthless. I have been using a real ground strap routinely to get into the habit. The Bertech mat with the connector will make it a bit easier.It was after Dave's video that I ordered bench covering to replace my silicone solder mat. (Got the blue, but I would imagine that is no longer the sine qua non).As for damaging parts, all education costs. Whether in felling trees (I am certified BTW), the stock market, electronics or mechanics. It is in the post mortem that we truly learn. Just wanna be the one doing it!I DO understand about the floor. While good for ESD, bad for electrician work. When I am in the panel I wear rubber chemical gloves just for the helluvit. Wiring is all current (pun) US code so that is good. And like I said, I wear rubber shoes.As an aside, I am pretty sure 120V is not going to stop my heart. I will not explain how I came to this opinion. I embarass myself enough.It is not about risk avoidance, it is all about risk mitigation.

author: m k
author_rank: Super Contributor
timestamp: December 16, 2023, 04:21:50 pm
content: Rubber shoes are disconnecting you from the floor and so more static charge is generated.Forget those shoes and insulate working area floor.The key here is not what you usually do.It's what you do when it's not usual.