What are the typical practices among the pmel people here (including active duty types). Our policy is basically that you wear them when you are working with exposed ESD sensitive components. But during calibrations, no. We have an individual trying to tell us we must wear wrist straps while calibrating items. Can't go into any actual details. Just wondering if there is a good consensus, and some good technical arguments for reasons to wear or not to wear them during calibrations.
Our ESD SOP was written following ANSI/ESD S20.20-2007 as a reference document.
We have one statement that reads: ESD handling precautions are designed to be used ONLY when ESDS items are un-powered. Safety hazards exist when powered devices are introduced into an ESD protective environment.
Thank you very much. That was exactly what I needed. As this is a little of an urgent circumstance (where there are those trying to force us to wear wrist straps during energized calibrations), do you know what paragraph references I might look at? I found a copy of the ANSI/ESD doc, and am going through it now.
On page 4 section 8.2 gives a blanket statement that personnel shall be grounded when handling ESD sensitive devises. On page 5 of section 8.3 the S20-20 standard addresses where wrist straps and other ESD protective measures are to be used. On page 2 section 6.3 says the standard can be tailored when the rationale is documented.
All PMELs I worked in had this rationale: Unless the covers were removed the ESD sensitive components inside the equipment was protected by the instrument design. Therefore wrist straps were not required unless the covers were removed. The design of the equipment enclosure is in fact an ESD safe enclosure because the equipment is already manufactured to an ESD standard. Reference the specifications of the equipment.
Thanks for that also great input. I am completely on this side. But we are in a touchy circumstance where people are trying to tell us we have to wear them. So I am scurrying to get some input from other experts in the field to help me fight this battle. Thanks again for that. I don't think this battle is over. But these inputs are VERY helpful.
Don't wear them around high voltage, they provide a path to ground with you as the fuse. I normally wear a heel strap, this time of year (here in Dallas) they prevent a lot of shocks with humidity in the low 20's.
It may be helpful to note that most labs have an SOP that will usually state the lower and upper RH the lab will operate within.
I can't recall any calibration procedure that directs the technician to wear a wrist strap during the calibration.
That's a totally bogus requirement. Whoever told you that does not know what he is talking about. ESD damage usually can only occur when a unit is opened and unplugged.
I agree 100% with everything everyone is saying. My issue is being at a customer site where they are trying to force us. And one of the individuals involved is an ESD "expert." I trained as an ESD instructor to MIL-STD-1686 years ago, and know the various technicalities. But this is one of those political battles where we will have to convince them that we are right. A technical detail is the difference between a "device" and an "instrument." They aren't getting that even when we explain it. So the answer is, I think, to provide them with something explicit from a national standard.
I only know of a few Keysight Network analyzers ( most 50Ghz ) that require ESD protection before touching the connectors. They even have warning labels around the connectors. To strap in to calibrate a sig gen or spec an is ridiculous. However, working for a commercial cal company I would just humor them and do it. :|
Quote from: flew-da-coup on 02-10-2016 -- 12:29:24
However, working for a commercial cal company I would just humor them and do it. :|
And adjust their bill upwards accordingly for being pains in the rear.
I have been reading through S20.20 and searching for some ISO standards. So far nothing definitive that addresses this issue but I'll put some more time into it and if I do find something that might help I'll post it. I don't want to end up wearing a wrist strap all the time.
Today I happened to be performing on site calibrations at a facility where semiconductor design is the primary function. As it happens one of their main designs is an ESD protection semiconductor that is produced in very large numbers. I asked to speak to the person in charge of ESD standards for that device and got an audience. I explained why I wanted to know if I should be using a wrist strap to perform calibrations at that facility and if he knew of a national or international standard addressing that. He did not know of any such standard and did not know who else to ask or where to look for such a standard. We did look at some of his equipment that has the EDS warning labels and he and I agreed that except for that and similarly labeled equipment no special ESD precautions were needed at his facility.
I am satisfied no national ESD standard will be found either for or against using any special ESD prevention during regular equipment handling and believe you are correct, this will be a political battle. I hope the other guy finds a reason to be as reasonable as the guy in charge of ESD standards at the company I was at today.
This was an interesting question and I am glad I learned about it. I am better prepared now if and when a customer asks me why I am not wearing a wrist strap. When they do I will diplomatically say, interesting you should ask...... and will endeavor to arrange things so he does not have a dog in that fight.
First, Briansalomon - Great post on the topic.
Thankfully, we prevailed, and after some tactical emails, we were able to convince them about good technical judgment in this matter. I wrote the following text that was sent to the customer from our quality manager:
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Our calibration technicians have been trained, and it is our quality policy that they are specifically not allowed to wear ESD wrist or foot straps while working on energized test equipment, as it is a safety hazard; and virtually all professional electronic test equipment are considered non-ESDS, so long as the covers of the instruments are closed (they are not sensitive to ESD damage). They are, however, to use properly connected wrist straps whenever they remove covers of unplugged only instruments, and work in contact or proximity with ESDS components.
This is an industry wide best practice; to both protect the technicians from accidental shock hazards, and because instruments with closed covers are not ESD Sensitive. This is a different issue than with unprotected ESDS semiconductor devices, which, understandably must have protections in place as detailed in ANSI/ESD S20.20-2007, which is the source of our policy.
So if we are to accommodate this deviation, please send written request from your quality manager for us to deviate from our policy, including a statement of understanding that we have objected to this both on grounds of safety hazards involved by varying from our policy, and that instruments involved in calibrations are not ESD Sensitive. Additionally, there should perhaps be a statement that [Customer's Company Name] will take responsibility for the hazards, and ensure that wrist straps provided to our technicians meet standards, and the benches they connect to have been properly tested for grounding and electrical phase.
Quote from: Hawaii596 on 02-11-2016 -- 08:44:02
Additionally, there should perhaps be a statement that [Customer's Company Name] will take responsibility for the hazards, and ensure that wrist straps provided to our technicians meet standards, and the benches they connect to have been properly tested for grounding and electrical phase.
Wow, hit 'em right in the old pocketbook...
Anytime you use a VNA for calibrations, you should use a wrist strap
Totally agreed that those specific exceptions are indeed the exceptions (as alluded to in an earlier post). Matter of fact, I may have our policy slightly modified to include that exception.
Quote from: CalibratorJ on 02-10-2016 -- 14:17:21
Quote from: flew-da-coup on 02-10-2016 -- 12:29:24
However, working for a commercial cal company I would just humor them and do it. :|
LOL, :-D
And adjust their bill upwards accordingly for being pains in the rear.