Hi, Derek. I know how it is. I also know there was no way was I going to take a chance on a reversed ground to a floating 'scope when I could get rid of the problem with one extra probe. FWIW, at 60 Hz it's easy to match probe and channel gain, and since we were only looking at decay time there was no need to buy a diff. probe. Where I work now we have some. HV ones, too!
On a recent assignment, a place I was helping was cited by their State OSHA equivalent for not having the power terminals on LISN's covered to prevent contact. There's a lot of stuff in a lab that can bite. Hard. Cheers, Cortland Richmond > [Original Message] > From: Derek Walton <[email protected]> > Subject: Re: scope probe gnd > > Hi Folks, > > I was keeping quiet.... but you know sometimes it's just too much. > > Almost all measurements I take in my lab use a differential scope probe. > The exception is when High voltages are involved. And I dont mean the > rinky dink two probes/scope math function either.... > > With diff probes I can connect anywhere to anywhere and measure it. I > never cringe hooking up the 0 volt reference side.... never sparks.... > > Give one a try, you will never go back. > > Derek Walton > > Cortland Richmond wrote: > > In a previous life -- at a company no longer around -- when our Safety > > Engineer quit we EMC types had to step in, and one of the very first things > > I did was get rid of a lethally ungrounded scope setup. It costs little to > > use probes rated for line voltage or better and dual channel math functions > > to allow proper safety grounds. > > > > Cortland Richmond > > > > > > > >> [Original Message] > >> From: Pettit, Ghery <[email protected]> > >> To: [email protected] <[email protected]> > >> Date: 3/10/2009 12:43:37 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! > >> -- > >> > > > > - > > ---------------------------------------------------------------- > > 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]>
