In another forum, fat16lib brought up that he specifically bought a grounded power supply from Phihong to minimize the measurement error /noise he was observing on his 16bit ADC. He confirmed that the ground is a pass-through design, so now his circuit is grounded to the mains ground. He observed much less noise on the board, resulting in better measurements.
I too am putting together an ADC solution with 16 bit resolution though so far my on-board switchmode power supply the VOF6 from CUI, is installed as delivered, i.e. isolated. It only features two input pins, Line and Neutral, and two output pins, 5VDC and GND.
I don’t know if there is a potential for my board to develop a ground loop going forward, but I thought it would be a good design practice to ground the PCB to earth in general. Thus, what are the downsides to grounding a PCB to earth? If one were to retrofit such a ground, would the best approach be to use a 2200pF, 2kV capacitor as suggested at Wikipedia? Would you fuse such a connection in case the outlet is hopelessly miswired or the AC ground develops a high potential for some other reason? Or perhaps use a very thin trace coupled with a 0805 fusible resistor with a low resistance for said connection?
For that matter, is it good design practice to always tie the purported AC ground and Neutral lines together on a PCB or to leave them separate? While I should be able to do this (assuming the outlet is wired correctly), experience in the field has taught me otherwise.