Originally Posted by
Pharos
When I was an apprentice with the Min of Tech., about 18 or 19, we all used a Tectronics scope with an I/P max of 1000v to look at the mains. There was never a problem, but things were much 'looser' then, one of us being 'flung' across the lab because his forearm touched a colour TV HT.
I appreciate the improved safety of using a transformer, but it will alter what is seen, particularly the HF end, and it will effectively 'profile' the FR.
Oh, and a last thought, my mains, which still has a certain '60s configuration and is still legal, has the mains -ve shorted to the mains earth with a chunky bit of metal.
I bet there are scopes specifically designed for HV.