What? if you disconnect the earth ground on the oscilloscope?
what? if you dont have the earth-ground on your outlet or NOT USING IT on the electrical plug
I once worked in a lab where all the? scopes were plugged into isolation transformers for this very reason.
and why my lab gear is? on a isolation transformer
You can also disconnect your scope mains earth pin so it's floating,
19:25 If that actually cause the computer to reboot, that is indeed very nasty. USB ports are usually fused and/or current limited. I believe they even have to be according to the USB specification.
09:23 It may very well be that your Dell supply disconnects itself from mains earth when the secondary doesn't have power, or even when the supply is not connected to the computer, to prevent the sleeve of the supply from touching anything and making sparks fly. You should do some more testing on this. Science!
19:25 If that actually cause the computer to reboot, that is indeed very nasty. USB ports are usually fused and/or current limited. I believe they even have to be according to the USB specification.
The comments on youtube just prove there are a lot of idiots out there playing with electricity
The comments on youtube just prove there are a lot of idiots out there playing with electricityDarwin Awards !
NEVER EVER disconnect the ground of your testequipment. it is the itum under test that needs to be put behind the isolation transformer !
19:25 If that actually cause the computer to reboot, that is indeed very nasty. USB ports are usually fused and/or current limited. I believe they even have to be according to the USB specification.
A bit after 20:0 I think I did actually hear slight static in the audio. Did you by any chance have the camera hooked up to mains power in the same plug pack as you powered the gadget or scope from?
What this video lacks for completness is clearly pointing out not to hook up your ground clips on both sides of the transformer.
There is a ton of stuff this video lacks for completeness!
There are countless scenarios that aren't covered I'm afraid.
Just look at the Youtube comments BAW posted.
What this video lacks for completness is clearly pointing out not to hook up your ground clips on both sides of the transformer.
There is a ton of stuff this video lacks for completeness!
There are countless scenarios that aren't covered I'm afraid.
Just look at the Youtube comments BAW posted.
Dave.
All large exposed metal objects in your house (water pipes and fixtures, ducts, and structural members, and metal appliances) are connected to the electrical ground. The purpose is to prevent large potentials from forming between two conductors, even in the case of a wiring fault. The idea is that if a live wire accidentally touches a grounded surface, a large fault current will flow through the ground connection causing the circuit breaker to trip.
I work in a development lab and we have all of our oscilloscopes on isolation transformers. If the test object is large, complex consisting of several parts connected to several computers it is not a realistic proposition to keep it isolated, someone will always mess up by connecting another instrument a programming tool or something that connects it to ground anyway, it is the test object that is messy and difficult to keep track of.
After a couple of exploded ground leads and one destroyed Tektronix TDS 3014 we put all of our oscilloscopes on isolation transformers and we had zero incidents since. Modern oscilloscopes are encased in plastic and if you connect it so that its chassis is "live" it is not easy to get in contact with it in order to electrocute yourself,
the ground leads are the biggest risk since they are handled the most and people don´t see that alligator clip as something risky, it is usually ground and therefore safe to touch.
Of course we are tying to keep everyone informed about our grounding strategy or what you want to call it, and educate them about the risks.
Why don't you use the proper tool for the job, which would be scopes with isolated channels (Fluke ScopeMeter, Tektronix TPS2000) or differential probes?
Does the manufacturer specify an insulation rating of the case? Or do you do your own certification? Did you do anything to isolate the BNC connectors and connections on the back (eg. USB, GPIB)?
So not only are you ignoring safety instructions regarding the scopes, you don't even use probes designed for floating measurements (eg. Multi-Contact IsoProbe series)?
I would hope there are at least big orange warning labels on all floating scopes warning not to touch them while the DUT is powered on. What kind of voltages and source impedances are you talking about? Do you at least take measures to limit the voltage between scope ground and PE to a safe level, like the Tektronix A6901 ground isolation monitor which grounds the scope if the voltage exceeds a certain safe level?
A little off-topic maybe.
Is it best to ground the scope, or having it floating (use a wall-plug without ground) when measuring or cars/engine-management systems?