I need a large power supply (a little over 1kW) for a consumer appliance that only has a single on/off switch and some non-conductive handles. An off-the-shelf isolated supplies run at least $60 for a sketchy Chinese supply that only supports either US or EU mains, whereas I could probably produce something similar to the following schematic for <$20 that would support both US and EU mains:
A lot of the cost savings would just be because I can afford to run the supply "dirtier" (higher ripple current) on input bulk capacitor(s). Even the output can be somewhat dirty, but I would plan to clean it up by using "smart" switching on the input to the buck converter.
However, safety is a concern. While from what I could tell from regulations there is no requirement that the power be isolated for my application, I would feel pretty bad (not to mention the financial ramifications) if someone got hurt somehow using a non-isolated design (e.g. got water into it and got shocked, if that's even possible). However, it seems like only a small portion of a non-isolated circuit is actually dangerous. As annotated in the schematic, is it true that mains is only dangerous to the extent that high voltages are involved, and that stepped-down but non-isolated voltages later in the circuit are "safe"?
Also note: I would plan to earth ground the metal case of the device (such that a short to live, and potentially neutral, would blow a fuse). And also, I would definitely have whatever final design I came up with reviewed by some experts; I'm just wondering if this is a plausible direction, given that using an isolated supply would probably make the product economically infeasible.
Edit: I'm going for 48V and actually closer to 1.2kW.
Sorry for not clarifying, but that ground symbol was not meant to mean that the circuit was connected to Earth (which would short the bridge), but rather just something I placed as required by the simulation software. The output side would be disconnected from any of L/N/G prongs, which I guess could cause some common mode voltage swing. However, the metal case would be earth grounded (and isolated from the rest of the circuit). Then if the live or the ground reference of the output side connected to the case the fuse would blow, but I guess if the pre-bridge neutral connected to the case, that may not be detected if there isn't an RCD (or I could add a low-rated fuse on the Earth ground path).