ungrounded oscilliscope question

[Grayscale]

first of, i would like to say hello to everybody here, since this is my first post. been watching the videos, great stuff,

i just recently started getting into electronics, cause i think it would help me in the long run in understanding certain devices or how they operate. i am an electrician, so i'm  not new to this world. but i would like to expand my knowledge. maybe with your help....

The subject of this post may have already caused some people to grind there teeth, i found out its kind of a touchy subject.  its because of this problem i have, recently i bought a used scope. Its a Phillps PM3540. the guy i bought it from showed me that every thing worked. the knowledge is had of scopes was that they where al grounded to mains earth. but when i got home and wanted to plug it in i noticed it had a plug without an earth pin. when i started reading the manual it said " A double-insulated power supply allows the frame ground to be directly connected to a floating ground circuit provided this ground does not carry live potentials". it also said in a big warning box that the probes ground lead should not be connected to live potentials. this should mean that this scope is " floating" i think.

my question is this. lets say i want to measure a 24Vac voltage. ground of this 24Vac is connected to mains earth. can i connect the probes ground lead to ground/earth and the probe to 24Vac. or should the mains earth be separated from the 24Vac ground.

seeing as i'm probably only gonna measure voltages right now, can i "view" the scope as a multimeter and always put the probes ground lead on the earth? or on ground if earth is not available for instance in dc circuits?

my confusion comes from the fact that if you measured with a grounded oscilliscope, the circuit your measuring on should be floating. but seeing as my scope is floating, does that mean i should be able to measured on circuits that have a common ground/earth?

i hope this al makes sense. its been a long time that i had to type in english. and it proved a little harder then i remembered.

anyways turned out to become quite a story. thanks for your help in advance.

[Tandy]

Being an electrician you will be familiar with fitting an isolated shaver outlet in a bathroom, your oscilloscope will be similarly isolated.

See this EEVblog post for useful information