ESD Safety: Too Conductive? - Page 1
Forum section: electronics / projects

author: iamdarkyoshi
author_rank: Frequent Contributor
timestamp: May 18, 2017, 10:47:41 pm
content: Hello again everyone. My current job at Tesla requires an ESD safe environment (ESD safe gloves, footcovers, and smocks) and the footcovers piss me off at the testing station. I'm usually TOO conductive.And it doesn't let me through. These footcovers have a carbon filled fabric which goes in my sock and runs under my shoe. But by the looks of it, I have to be within a certain range of values. (It tests from my finger to each foot by the looks of it)I end up just stepping halfway off the foot pads on the tester, and this usually lets me through.But is being TOO conductive an issue? Or is the programmer of the machine just dumb?

author: DBecker
author_rank: Frequent Contributor
timestamp: May 18, 2017, 11:15:08 pm
content: Being too conductive puts you at a higher risk of a fatal shock.That's why anti-static wristbands are grounded through a 1 Mohm resistor.

author: mmagin
author_rank: Frequent Contributor
timestamp: May 18, 2017, 11:16:25 pm
content: Presumably these foot covers are designed with the assumption they'll come into contact with no bare skin, but in your case they are?

author: iamdarkyoshi
author_rank: Frequent Contributor
timestamp: May 18, 2017, 11:20:32 pm
content: Quote from: mmagin on May 18, 2017, 11:16:25 pmThey have a strap dangling off the end that you are supposed to shove in your sock:Quote from: DBecker on May 18, 2017, 11:15:08 pmThats what I thought, but there is no way of adjusting these shoe covers...

author: mmagin
author_rank: Frequent Contributor
timestamp: May 18, 2017, 11:25:37 pm
content: Quote from: iamdarkyoshi on May 18, 2017, 11:20:32 pmThat strap should have a 1M ohm resistor in it. Somebody's started buying defective shoe covers.

author: iamdarkyoshi
author_rank: Frequent Contributor
timestamp: May 19, 2017, 01:13:54 am
content: Quote from: mmagin on May 18, 2017, 11:25:37 pmThey are disposable items (they are mostly to keep our floor clear of outside dirt) so the strap IS the resistor, it has a resistance. But it seems to be too conductive...

author: mmagin
author_rank: Frequent Contributor
timestamp: May 19, 2017, 04:10:24 am
content: Ok. Seems strange that you would be special however. Maybe nobody else is using them correctly? Or you're the only one who bothered to care?

author: Someone
author_rank: Super Contributor
timestamp: May 19, 2017, 05:11:27 am
content: Quote from: iamdarkyoshi on May 18, 2017, 10:47:41 pmIt can be a danger depending on the voltages you are exposed to, but these units tend to be configured with a fixed or overly safe default limit. This is a problem when people like you on the extreme end of skin conductivity arrive and if you're not touching any voltages above 12V it should be fine and the limits reassessed (50k ohm, 0.5mA, ergo 25V).

author: iamdarkyoshi
author_rank: Frequent Contributor
timestamp: May 19, 2017, 05:28:08 am
content: Quote from: mmagin on May 19, 2017, 04:10:24 amThis tester has a gate on it and lets one person through per passing test. I'm sensitive to high temperature (I like it 5-10 degrees colder than anyone else) so I tend to sweat a lot, which increases my skin conductivity drastically.

author: Gyro
author_rank: Super Contributor
timestamp: May 19, 2017, 08:44:01 am
content: QuoteMaybe try tucking the strap into your shoe rather than sock? It sounds as if you may have enough moisture happening in there to get you into the 1Meg range!

author: Fungus
author_rank: Super Contributor
timestamp: May 19, 2017, 01:20:37 pm
content: Quote from: mmagin on May 19, 2017, 04:10:24 amSweaty feet?

author: jh15
author_rank: Frequent Contributor
timestamp: May 20, 2017, 04:56:29 am
content: Ask your group leader, boss, test equipment department. They set this up, should not be your problem.I had to suddenly set up a plant-wide esd program in '84 or so on time for plant vs vendor esd issues. Static mats wristt straps, chains on focusing wrenches for sensitive ir pin diodes, etc.I was a bit overwhelmed at first, but many, many production issues of the past on other items went away after setting up.Even (almost) retired and still playing the field, I keep my esd faraday lab coat and wrist strap on.From pinballs to (non-profit) broadcast studio equipment, and my hobbies.I think it is really cool that the car I just bought thinks as much about care in manufacturing in their consumer division as in Spacex.And I heard it here... amazing, maybe not so, id hard to quit reading this forum.I always wear a seatbelt in a car, don't like the law though. I hope I won't get arrested for not wearing an esd strap in my lifetime though.If my tesla crashes, and I didn't have my esd strap on, would I be denied insurance coverageBut then, it looks like as above, not a thing to worry about?

author: iamdarkyoshi
author_rank: Frequent Contributor
timestamp: May 21, 2017, 04:03:38 am
content: Quote from: jh15 on May 20, 2017, 04:56:29 amCongrats on your new purchase!