power - RCD tripped when measuring with a scope

Below was my setup:

The moment I connected the probe the RCD tripped.

My scope was earth grounded. Does that mean I shorted the neutral and the earth ground? I know that neutral and earth are connected somewhere outside the building or at the utility transformer. But I completely forgot about it.

And what can I do to prevent that that? Which one is a safe solution: using an unearthed plug for the scope or a 1:1 isolation transformer? Any ideas?

1:1 isolation transformer might not be okay for all cases and might corrupt the original waveform?