I understand the concerns and your reasoning, but if you define accessible as "anything I CAN touch", then it would inlcude all surfaces, connectors and the like...
There was considerable discussion in the Working Group regarding this issue, and as I recall, the concensus was that for compliance purposes, there can be "accessible" points and ports that are unlikely to be accessed by the operator during the normal use. These points, surfaces and ports can then be exempted from ESD testing. It's my feeling that the intent of the standard is to insure that the product is immune to human ESD events that are likely to occur during normal use -- in other words, test those points and ports the operator is likely to come in contact with during normal use; don't bother with those points NOT likely to be touched by the operator during normal use.... This is only for compliance purposes.... Maybe not good engineering practice, but that's where the second head comes in -- you'll probably have a more rugged and reliable product if you do test everything, but that's up to the manufacturer, not the compliance body. Best Regards, Michael Hopkins Manager, EMC Technologies Thermo Electron Control Technology Division EMC & ESD Simulation Solutions One Lowell Research Center Lowell, MA 01852 Tel: +1 978 275 0800 ext. 334 Fax: +1 978 275 0850 michael.hopk...@thermo.com One Thermo, committed to integrity, intensity, innovation & involvement From: Chris Maxwell [mailto:chris.maxw...@nettest.com] Sent: Tuesday, June 24, 2003 11:16 AM To: Mike Hopkins; don_borow...@selinc.com; emc-p...@majordomo.ieee.org Subject: RE: ESD - not applicable ? Mike, I'm still not sold. I understand the specific exemptions for circuit cards, battery compartments and the like; but I can't follow the reasoning for exempting the outside of the product. How are you defining "not accessible"? It sounds as though you are gauging access by the need to touch a surface; not the ability/opportunity to touch a surface. For instance, I have two speakers attached to my PC. One of them is a "slave". It doesn't have any volume controls on it. I never have to touch it once it is installed. Isn't it still "accessible" even though I don't have to touch it? If I were to mount this speaker up on a wall; it does reduce the probability that it will be touched while it's operating; but it doesn't eliminate it. So, I still consider it "accessible". I understand that height is involved in the original question (device is installed higher than 2.5m from the floor). The problem here is: the product still can be touched; and I see no specific guidelines in any standard that says "a product higher than "x" meters off of the floor is "not accessible". To me, there are too many gray areas in this argument. My compliance head says that the outside surfaces that can be touched should be tested. AND I'M USUALLY ONE OF THE COWBOYS, LOOKING FOR EVERY LOOPHOLE I CAN FIND :-) I do agree with you on one point. If I were to exempt this product from ESD testing; I would cover my butt and label it as ESD sensitive. I think we both agree, from a quality standpoint, that ESD testing would be a good thing to do. One point that I'm sure of agreement/disagreement is indirect ESD testing. I think that, regardless of how you treat the surfaces; this product still needs indirect ESD testing. Do you agree with this? Best regards, Chris Maxwell | Design Engineer - Optical Division email chris.maxw...@nettest.com | dir +1 315 266 5128 | fax +1 315 797 8024 NetTest | 6 Rhoads Drive, Utica, NY 13502 | USA web www.nettest.com | tel +1 315 797 4449 | > -----Original Message----- > From: Mike Hopkins [SMTP:michael.hopk...@thermo.com] > Sent: Tuesday, June 24, 2003 9:38 AM > To: 'don_borow...@selinc.com'; emc-p...@majordomo.ieee.org > Subject: RE: ESD - not applicable ? > > > You always need to apply two heads --- the engineering head says,"Good > engineering practice says you should test for ESD", but the compliance head > only needs to meet the requirement of the standard, which clearly exempts > points and ports NOT accessible by an OPERATOR. > > Points and ports accessible for maintenace, installation and service need > not be tested (compliance head). Points/ports that ARE accessible by the > operator can be exempted by labeling -- i.e., ESD sensitive ports such as > scope vertical amp inputs, RF antenna inputs, etc... Also specifically > exempted from compliance to 61000-4-2 are inside battery compartments, which > although accessed by the operator, are rarely accessed and when they do get > into the battery compartment, the unit is inoperative.... > > > > > > Best Regards, > > Michael Hopkins > Manager, EMC Technologies > Thermo Electron > Control Technology Division > EMC & ESD Simulation Solutions > One Lowell Research Center > Lowell, MA 01852 > Tel: +1 978 275 0800 ext. 334 > Fax: +1 978 275 0850 > michael.hopk...@thermo.com > > One Thermo, committed to integrity, intensity, innovation & involvement > > > This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. 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