Hi, We all know that with an isolated offline SMPS, the isolated secondary ground will generally be at earth potential or thereabouts (even if not directly connected to earth). -And this being due to the stray high impedances across the transformer/ the Y caps, etc etc.
However, at least in theory, such an isolated secondary may float up to mains peak in voltage.
As such, its quite common to see a 1MEG resistor being used across the isolation barrier of the offline SMPS, in order to bleed off any charge on secondary ground that would cause voltages well above earth potential that would otherwise build up.
So what regulations cover this use of an isolation barrier resistor?
(I remember once working at a TV power supply company. It was quite common for an engineer to go off for coffee break…and while absent, his mates would snip off the 1MEG isolation resistor on his test board….. then on return from coffee break, the engineer would get a zap from touching the isolated secondary side circuitry….and hoots of laughter would follow from his pals.)
Do you mandate use of such 1MEG resistors?