I caught sight of this thread and though I would weigh in since I am an owner and regular user of a Fluke 199C scopemeter which is similar in function to your Tek THS unit.
On point #1: It would be safe - on paper- to use your scope to monitor a 220vac mains directly without 10x probe. It is a bit nerve wracking though, because you do not have a very large amount of headroom for noise spikes. There would only be 80vrms ac, and there could be peaks much larger than that coming down the line (think lightning strike or trees crossing lines). The scope could handle some of this, but why risk it? That is why I really like and use the 10x VPS2xx series probes that are used with the Fluke scopemeters. They have accessory clips like alligator and spring grabbers that allow you to do what you are wanting with the multimeter leads and banana to BNC adaptor, but have the additional safety of a 10x probe, and the cat. rating that goes with.
Point #2: The scope is isolated from ground, but there is a limit. The internal breakover point between the isolated shell of the BNC and the scope system ground is up to 600 volts. That is to protect you from floating the scope too high above ground and risking an arc-over that damages the scope - or worse yet - you!
Point #3: The 30 volt rms limit is what most safety agencies deem the maximum voltage exposure that a human can contact before electrocution becomes a possibility (I happen to think it is possible to get shock injured at much lower voltages under the right circumstances). With uninsulated cabling or BNC connectors they want you to limit the voltage that might be present at the two BNC shells to 30 volts to prevent accidental contact shock hazards (human safety).
The point of all of this is: Use insulated accessories as much as possible. Use Tek 10x probe as much as possible.
If it were me, I would watch on e*ay for a Fluke VPS 2XX series scope probe with the accessory clips. I have no qualms about connecting my Fluke directly to a power service entrance panel for 110v or 220v monitoring using these probes and the fat alligator probe tips.
Best of luck with your great find!
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