Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!uunet!microsoft!kentsu From: kentsu@microsoft.UUCP (Kent Sullivan) Newsgroups: comp.sys.cbm Subject: Re: Grounding Oneself, the right way...??? Message-ID: <9227@microsoft.UUCP> Date: 1 Dec 89 20:08:07 GMT References: <6058@cbnewsh.ATT.COM> <10936@max.u.washington.edu> <5126@tekgen.BV.TEK.COM> <11128@max.u.washington.edu> <1239@uwm.edu> Reply-To: kentsu@microsoft.UUCP (Kent Sullivan) Organization: Microsoft Corp., Redmond WA Lines: 63 In article <1239@uwm.edu> jgreco@csd4.csd.uwm.edu (Joe Greco) writes: >Since most people service their units on a workbench, it is probably most >logical to ground your unit to earth ground and get a wrist strap type >grounding gadget and ground yourself to earth ground. You should be very >safe, but such extreme measures probably are not needed unless the air is >very dry and you are in a bad environment. > >Me? If I'm worried, I touch an outlet and then the ground plane of the >unit. Thought you-all might find this article interesting--it's from comp.sys. mac.hardware, where a very similar discussion is winding up: ------------- From uunet!snorkelwacker!think!samsung!uakari.primate.wisc.edu!ames!ncar!boulder!rieman Fri Dec 1 11:56:12 PST 1989 Article 570 of comp.sys.mac.hardware: Path: microsoft!uunet!snorkelwacker!think!samsung!uakari.primate.wisc.edu!ames!ncar!boulder!rieman >From: rieman@boulder.Colorado.EDU (John Rieman) Newsgroups: comp.sys.mac.hardware Subject: Re: Memory Questions Message-ID: <14328@boulder.Colorado.EDU> Date: 29 Nov 89 08:20:29 GMT References: <4129@phri.UUCP> <3122@jarthur.Claremont.EDU> <5671@umd5.umd.edu> <3231@jarthur.Claremont.EDU> <381@fsu.scri.fsu.edu> Sender: news@boulder.Colorado.EDU Reply-To: rieman@boulder.Colorado.EDU (John Rieman) Organization: University of Colorado, Boulder Lines: 25 [a series of articles suggest grounding yourself to various household objects...] Like outlets, cold-water pipes are only theoretically safe. Water utility folk and plumbers are taught to exercise extreme care with water pipes, since a faulty appliance can turn the cold-water pipe "hot." Even if the pipe is a good ground, wiring yourself to it while you open up a 110V device is less than smart -- it's too easy to get caught up in the excitement and plug the Mac back in, just to see if it's gonna run. Then when the bomb appears, you figure you'll just wiggle a board and... PZZZZT! Anyway, as I understand it, what you want is not (necessarily) an absolute "ground." You just want the potential between you and the machine to be zero. If you're both floating at 500 V relative to some Platonic ideal ground, no problem. The recommendation I've read, which I've seen VAX, Apple, and various other professional computer service people follow, is just this: Unplug the machine, snap a grounding strap around your wrist, and clip the lead from the grounding strap to the machine's chassis. For board-level work, such as installing chips, try to find a metal desk or table, and ground yourself and the equipment to that. (Don't wear polyester and don't shuffle your feet -- probably good advice in any case.) - john ----------- What John says is very important: you don't need an absolute ground, but rather a ground where the *potential* between the machine and you is zero. The ground strap is a very effective method. Kent Sullivan Microsoft Corporation The opinions expressed in this article are my own and do not necessarily reflect those of my employer.