a thing I am always vaguely uneasy about is when I see a commercial mains LED panel where they're feeding rectified 320V into a long LED chain but with no conformal coating on the aluminium PCB. not from a "if you touch this it's gonna hurt" perspective, but like... an ant or some moisture gets into the case, arcs across one LED, and the parasitic inductance of the path causes ringing which triggers a cascading series of arcs over each LED, ultimately frying the entire panel in one fell swoop.