Max oscilloscope voltage at BNC

Question

I know this question has already been asked, but some inconsistencies are bugging me and I wanted to find a definitive answer.

I have recently bought a Rigol DHO924s.

The silkscreen on the device and the “vertical system analog channel” part of the datasheet both say the max voltage is 300 V RMS CAT I.

This leads me to believe that the scope can survive 300 V RMS at the BNC without damaging its internal circuitry.

However, would it be possible that the “max 300 V RMS” is actually the max voltage using a 10x probe, meaning that more than 30 V at the BNC could damage the scope?

Since the menu of the scope only allows the vertical scale to be 30V using a 1x probe, I was wondering if I might damage it by accidentally making a voltage spike that surpasses 30 V. (Or actually 40 V since the datasheet says Vpk can be 400 V.)

Answer 1

The oscilloscope maybe cannot digitize right input voltage higher than 100V without a probe (momentary value when the sensitivity setting is 10V/div) but the analog channel input stands more. Or at least the manufacturer promises so. This is a screenshot of the spec sheet:

Hopefully you know that CAT I means "no connection to mains AC". You may wonder why such limitation is added? In theory the mains AC peak voltage could well be covered by the promised 400Vpk limit. That's because mains AC contains random peaks which can well exceed the 400Vpk limit - maybe short ones, but it's still over 400Vpk and the manufacturer promises nothing about such usage - except hints that the days of the instrument may get short.