[Crosseye_Jack]

I would add "In a small space" Making an larger power supply that keeps the high and low sides adequately separated is pretty easy and cheap as long as you stick to genuine components.

But that then leads onto the whole fake component issue. For example the component will be a optocoupler but the dirt cheap knock off supply may not be using the same level of quality or a knock off component as those found in genuine power supplies which _could_ create a High to Low voltage path if that part failed.