using multiple devices on the same isolation transformer.

Never ever use an ungrounded scope (*). It is not safe.

Watch this, please:

https://www.youtube.com/watch?v=xaELqAo4kkQ&

(*)Unless it is a battery powered one, of course…

@calambres if you rewatch that video as I just did, you will see he talks about using an isolation transformer on your scope to eliminate ground loops. he doesn’t recommend using an isolation transformer on some scopes. my scope has a plastic housing. there is no chance of an electrocution by touching the side of my scope if a hot wire touches the housing on the inside of the scope. thank you for your answer but that was NOT my question.

I’m not exactly sure what your question is getting at. But, yes, if it’s big enough, it will power up all of your equipment. But then, all of that equipment will be referenced to each other, even though it’s isolated from the mains power. So let’s say you have an AA5 radio, and your scope plugged into the isolation transformer. It’s possible that the scope’s negative lead is common to the neutral – you would need to verify with a continuity test. If so, and if the AA5 isn’t wired correctly with a polarized plug, AND the plug is inserted wrong, you will still get a big problem when you attach your scope’s ground lead, as everything on the isolation transformer has the same hot, and neutral reference. YOU may not get shocked, but referencing everything together, can cause problems, if you aren’t super careful about connections.

Zippy. of course you can do whatever you consider to be right. Once said, I would never plug a scope into an isolation transformer no matter whether its specs can handle it or not.

https://www.tek.com/en/documents/technical-brief/floating-oscilloscope-measurements-and-operator-protection

Quote from that document:

WARNING

Never attempt to defeat the protective grounding system of your oscilloscope by using an isolation transformer (left) or disconnecting the ground connector on the power plug (right). Failure to follow safety warnings can result in serious injury or loss of life.

That said, if you know exactly what you’re doing you may be fine but to me it’s too dangerous to be even tried. Just plug the DUT in the isolation xfmr and let the scope grounded as it is designed to be used.