Agreed on the dangerous aspect but I have had issues with ground loops
between an audio generator and the scope when testing audio
amplifiers. I carry a ground lifter in the scope probe bag and use it
when needed - not very often.


** Typical ground loops can be eliminated by fitting a resistor between the
scope chassis ground and safety ground of about 10 to 22 ohms. For obvious
safety reasons this resistor must be protected by shunt diodes in each
polarity.

A simple way is to use a 25 amp rated bridge rectifier and connect the
resistor across the AC input terminals while shorting the " + " and " - "
terminals - giving two diode drops in each direction with current capacity
enough to trip a 20 amp supply breaker if necessary without damage.

The bridge and resistor can go inside the scope.


.... Phil