It seems a double edged sword, fire and burn hazards with a ground and electrocution without it. So perhaps it just goes back to controlling use to properly trained personnel, who understand that a scope may or may not be floated depending on what is being measured and the desires of the last operator....
Just about all test equipment can be dangerous in the wrong hands. From: [email protected] [mailto:[email protected]] On Behalf Of Douglas Smith Sent: Wednesday, March 11, 2009 1:57 PM To: Piotr Galka Cc: EMC-PSTC Subject: Re: scope probe gnd Hi Everyone, I remember the time many years ago when I "welded" a scope probe to the circuit by accidentally connecting the ground lead to the -48 volt supply on a telecom board instead of the probe tip (got them reversed as the two nodes looked similar). Sort of embarassing......... Doug Piotr Galka wrote: > During lab exercises at study my friend sitting next to me tried to > see with the scope the voltage at diode in thyristor circuit. > One of three phases at 3-rd floor of Electronic department dead. > The lab teacher told him to think once more what he is doing. > So he thought some time, than reconnected his scope and his thyristor > circuit to another phase and ... next phase dead. > After this second experiment whole his circuit looked like it was > painted with black spray. When he suddenly jumped back of his desk I > looked there and sow some copper paths separated from his PCB and > firing on the desk. > 10 or more years later I was travelling by train. Three students were > sitting in the same compartment. At one moment one of them began to > tell my friend's story to the others. I was seriously surprised. > > Piotr Galka > > > ----- Original Message ----- From: "Pettit, Ghery" > <[email protected]> > To: <[email protected]> > Sent: Tuesday, March 10, 2009 5:40 PM > Subject: RE: scope probe gnd > > >> Or there were the old scopes where you used patch cords and banana >> jacks. We had what was left of the power cord for one such scope >> hanging in the front of the motors lab in college that showed the >> importance of having your setup checked before applying power. Seems >> the hot and ground leads to the scope from the motor being measured >> got reversed and the 120 VAC supply was bypassed to ground through >> the green wire in the power cord. For a short period of time. Then >> the green wire acted as a fuse. That cord was NOT repairable. And, >> NO, I was not the culprit. Didn't happen on my watch. >> >> Ghery Pettit >> >> >> -----Original Message----- >> From: [email protected] [mailto:[email protected]] On Behalf Of Ralph >> McDiarmid >> Sent: Tuesday, March 10, 2009 9:35 AM >> To: [email protected] >> Subject: RE: scope probe gnd >> >> Once for me as well. I never forgot that lesson. >> >> >> Ralph McDiarmid, AScT >> Compliance Engineering Group >> Xantrex Technology Inc >> >> >> -----Original Message----- >> From: [email protected] [mailto:[email protected]] On Behalf Of John >> Woodgate >> Sent: Tuesday, March 10, 2009 5:47 AM >> To: [email protected] >> Subject: Re: Surge testing Questions >> >> In message >> <9d04b979323dcd428297dda95108893e0120c...@bb-corp-ex2.corp.cubic.cub> >> , dated Tue, 10 Mar 2009, "Price, Edward" <[email protected]> >> writes: >> >>> What, you never had that happen?! >> >> Only once - so far! >> -- >> OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk >> Things can always get better. But that's not the only option. >> John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK >> >> - >> ---------------------------------------------------------------- >> This message is from the IEEE Product Safety Engineering Society >> emc-pstc discussion list. To post a message to the list, send your >> e-mail to <[email protected]> >> >> All emc-pstc postings are archived and searchable on the web at: >> http://www.ieeecommunities.org/emc-pstc >> Graphics (in well-used formats), large files, etc. can be posted to >> that URL. >> >> Website: http://www.ieee-pses.org/ >> Instructions: http://listserv.ieee.org/request/user-guide.html >> List rules: http://www.ieee-pses.org/listrules.html >> >> For help, send mail to the list administrators: >> Scott Douglas <[email protected]> >> Mike Cantwell <[email protected]> >> >> For policy questions, send mail to: >> Jim Bacher: <[email protected]> >> David Heald: <[email protected]> >> >> - >> ---------------------------------------------------------------- >> This message is from the IEEE Product Safety Engineering Society >> emc-pstc discussion list. To post a message to the list, send your >> e-mail to <[email protected]> >> >> All emc-pstc postings are archived and searchable on the web at: >> http://www.ieeecommunities.org/emc-pstc >> Graphics (in well-used formats), large files, etc. can be posted to >> that URL. >> >> Website: http://www.ieee-pses.org/ >> Instructions: http://listserv.ieee.org/request/user-guide.html >> List rules: http://www.ieee-pses.org/listrules.html >> >> For help, send mail to the list administrators: >> Scott Douglas <[email protected]> >> Mike Cantwell <[email protected]> >> >> For policy questions, send mail to: >> Jim Bacher: <[email protected]> >> David Heald: <[email protected]> >> >> - >> ---------------------------------------------------------------- >> This message is from the IEEE Product Safety Engineering Society >> emc-pstc discussion list. To post a message to the list, send your >> e-mail to <[email protected]> >> >> All emc-pstc postings are archived and searchable on the web at: >> http://www.ieeecommunities.org/emc-pstc >> Graphics (in well-used formats), large files, etc. can be posted to >> that URL. >> >> Website: http://www.ieee-pses.org/ >> Instructions: http://listserv.ieee.org/request/user-guide.html >> List rules: http://www.ieee-pses.org/listrules.html >> >> For help, send mail to the list administrators: >> Scott Douglas <[email protected]> >> Mike Cantwell <[email protected]> >> >> For policy questions, send mail to: >> Jim Bacher: <[email protected]> >> David Heald: <[email protected]> > > - > ---------------------------------------------------------------- > This message is from the IEEE Product Safety Engineering Society > emc-pstc discussion list. To post a message to the list, send your > e-mail to <[email protected]> > > All emc-pstc postings are archived and searchable on the web at: > http://www.ieeecommunities.org/emc-pstc > Graphics (in well-used formats), large files, etc. can be posted to > that URL. > > Website: http://www.ieee-pses.org/ > Instructions: http://listserv.ieee.org/request/user-guide.html > List rules: http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > Scott Douglas <[email protected]> > Mike Cantwell <[email protected]> > > For policy questions, send mail to: > Jim Bacher: <[email protected]> > David Heald: <[email protected]> > -- ___ _ Doug Smith \ / ) P.O. Box 1457 ========= Los Gatos, CA 95031-1457 _ / \ / \ _ TEL/FAX: 408-356-4186/358-3799 / /\ \ ] / /\ \ Mobile: 408-858-4528 | q-----( ) | o | Email: [email protected] \ _ / ] \ _ / Web: http://www.dsmith.org - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]> - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
