Q on grounds..

Assume a "black box" controller with reed relays for inputs and its power supplied via a transformer from "mains" has its own "ground", and that the outputs are optically isolated triacs that drive relays, power coming from same "mains" that (naturally) has its own return line "neutral" as well as its "ground".
Now it is possible that a large static voltage could be generated between the "black box" "ground" and the power "neutral", including an induced half-voltage AC due to capacitance from "black box" transformer primary to secondary.
So..for safety (and code compliance), what is needed to connect these together, and what does one do with the AC "ground" line WRT hese other "grounds"?

**
Please refer to the stupidity documented in EDN Sept 17 issue page 56 where the "solution" was longer insulation standoffs from an earth-grounded box and the electronics.
I say "stupidity" in that yes, the original failures were caused by the equivalent of lightning induced ESD, and that the longer standoffs "solved" the damages.
All that did was increase the amount of induced voltage required to ZAP the units; a direct connection bus i think would be far better, and perhaps a (carefully) selected resistor might be better yet.
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Relevant Pages

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