If the scope is isolated from ground, the chassis is hot to ground. If you connect the scope to another piece of gear (like to a PC running Wavestar) the hot chassis will be shorted to ground through the com cable and the PC ground.
If you touch the scope (like many of us are prone to do) then you will get shocked by the hot chassis. Floating the scope is a dangerous and risky practice. It is much safer to float the equipment. If you have a two channel oscilloscope, you can use the difference function to make measurements. One probe tip goes to ground. The other probe tip goes to the point you want to measure. The difference plot on the scope shows the potential between the test points. Joe Smalley Rural Kitsap County WA Fiesta 48 volts NEDRA 48 volt street conversion record holder [EMAIL PROTECTED] ----- Original Message ----- From: "Victor Tikhonov" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Monday, October 14, 2002 12:35 PM Subject: Grounding scope (was: Yet another charger question) > One must be careful here when working with non-isolated equipment > such as PFC chargers. > > If you want to see/measure the voltage difference between two points > both of which are at some potential (not grounded), grounded scope > may cause your device blow up as well as ground pin lead. Been there. > If the scope is floating (or connected to the mains through isolation > transformer and then grounded to equipment chassis) you're OK. > > You have to know what you're doing. > > Victor >
