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I've designed a board with a few relays that switch 120VAC. I have the normally open side of the relay connected to a current limiting resistor and opto-isolator. Do I need to worry about single fault failure for safety testing? If so, can I just put two resistors in series?
I read many times, form many sources, that 60 VDC or 30 VAC are potentionally dangerous. I know that it is current what matters, but higher voltages lead to greater currents (assuming same resistance, of course).
I also know that primary and secondary windings of a transformer are dangerous.
I hate procedures because they inevitably inhibit innovation and generally waste time with a load of meaningless waffle. But procedures are important.
One area that worries me is electrical safety.
Members, including me, often post schematics for circuits which involve dangerous voltages...