Peter Cousens wrote . . .

>Most people will have their own preferences for their own reasons.
>Me I float all my test gear but connect all the chassis together
>but not to earth. On the scope I use the earth socket on the
>front so I can independantly float it when required
>I have floated my scope since my first job where all the scopes
>were floated

Most techs that I know float their test equipment.  I also do so, but with
the Earth lead connected to ground through a largesh bridge rectifier wired
up as a 1 to 1.2 Vdc shunt.  That is... take a 100 PIV 35 Amp bridge, short
the + & - terminals together, connect the Earth lead of the scope to one of
the AC terminals, connect the other AC terminal to Earth Ground.  So long as
the scope chassis remains within about 1 Vac p-p of ground, the bridge does
not conduct and ground loop currents don't mess up your low level
measurements.  Sometimes it is necessary to truly lift the ground lead, but
I find those situations rare.

>
>I fail to see the point of isolation transformers on test gear
> unless the filter caps have excessive leakage or its open
>'cause your fixing it or you're suffering from
>incontinence and sitting on it.
>
What they mean is to use an isolation transformer to power the system under
test thru the iso transformer, NOT the test equipment.  The whole idea is
that anything connected directly to the power line (old radio and TV
equipment, off line switch mode power supplies, etc) is then isolated by the
transformer so that safer measurements can be made.

Dwayne