I have a question for the experts here .... In my field sometimes I have to take some pretty dangerous measurements. By that I mean looking at a waveform across a device that might be 600 volts DC off ground (yikes). Since isolated probes are extremely expensive, it is (unofficially) routine to break the rules by 'floating' the case of the scope on an insulated surface and using an isolation transformer to power the scope (and not touching the case when the power is on). The question is, are there any special considerations with this new digital scope that would make things any different from the old analog scope when making floating measurements like this? (Obligatory note: I work with dangerous equipment that has dangerous voltages and this practice is not recommended. You're supposed to buy an isolated/insulated scope and/or an isolated probe. Don't try this at home or at work. I already know this.)
--Wyatt--
Not an expert, but there is a safer alternative, but you are still dealing with high voltages so the only safe way will be not to do things you don't fully understand that are dangerous.
You can use 2 channels with A+B and inverting B, like people been doing it on analog scopes when you need to measure voltages that are not ground referenced to your equipment after removing the ground clips on your probes.
Still you need good quality probes for the task and your scope should be able to handle that voltage. In the case of the DS1054Z is only rated up to 300V RMS, not sure on DC you will have to look up the specs.
Also the probes that come with it are probably no good for 600V.
And finally, Math function on digital scopes (at least at this price level) required to do the A + Inverse B, is not particularly fast, but should be fine for low frequencies or when real time is not that important.
I wouldn't use this scope for measuring anything higher than mains, and I wouldn't use it to measure mains because there is rarely a reason to do that when you can use a DMM instead for most tasks.