I'm trying to trace a very intermittent fault on my PC/telecoms network. If I want to connect my Picoscope across the incoming phone line to monitor for transients what's the best way to do this? I already know about the -48V line level and the 90V ring signal, the main concerns are which way round ...

Sorry for shouting in the title bar but we're talking about life and limb here. Both the scope and your computer will react very badly if subjected to mains voltages, even through a 10:1 probe. Amongst the problems are: 1) What is the breakdown voltage of your 10:1 probe and are you sure that it can...