Re: Scope grounding and generators

Tony Fleming

Are the new digital scopes also grounded to the earth ground? Only when
plugged into 120V and not using the battery that is inside to usually power
my digital scopes.
I like this diagram:;_ylt=AwrCmmD9e5VfhFgAbywPxQt.;_ylu=Y29sbwNiZjEEcG9zAzEEdnRpZAMEc2VjA3Nj?p=connect+isolation+transformer+AND+oscilloscope&fr=yhs-iba-syn&hspart=iba&hsimp=yhs-syn#id=9&
I have a couple isolated transformers that I use when working on old stuff
like Radios and TV's....

*My understanding is that as long the path can't find the earth ground in
any combination, I should be safe.*

Excluding my Tektronix 2465 DMS that is grounded to earth ground and in
case I need to isolate my "path" I have isolation transformers for that.
Many experienced people make mistakes even today, despite knowing this
little problem that can cost $$$ or hurt you beyond repair.
Am I wrong or is there a "path" that can "bite me anyway" ?

On Sat, Oct 24, 2020 at 10:50 PM Chuck Harris <> wrote:

At issue is how the generator is internally connected, and
the possibilities of accidents.... and on whether or not you
are willing to bet your life that the generator is connected
the way you think it should be, and that it hasn't any faults.

For instance, you scope's ground wire is connected to earth
ground through the power cord.

Your generator should also be grounded, but if it isn't, an
accidental connection between the generator's hot lead and
the scope's ground, could cause the generator to be elevated
120V, or more, above the scope's front panel.

As I stated earlier, I use a filament transformer for such
measurements. Its fidelity is very good, and most are isolated
for several hundred volts... actually many of the older
filament transformers are good for 3000V.

-Chuck Harris

Robert Simpson via wrote:
Since I will not be connecting the generator to house power, I should be
safe connecting house ground for my scope test. I want to see the shape of
the power, the frequency and peak voltage. I think a scope will be my best
tool for that. Besides, why have a scope if I don't use it whenever

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