Recommended · for some experience
EEVblog #659 - Medical Plugpack Teardown
Why people recommend it
EEVblog takes apart a power supply built to medical standards, cited as a practical look at the isolation and spacing needed for safe mains design.
Watch for: Relevant to mains-powered projects, where faulty isolation or spacing can kill.
In their words
Separate to standards means clearance, creapage etc. You can look at some teardowns to see what's involved; here's one to medical standards:
got trolled too much this week on electronics.stackexchange.com, Oct 2015. CC BY-SA.