MIL-P-1629 from 1949 formally defines fail-open mechanical switches that release pressure on failure.
replyThe concept goes back to a pressure cooker invented in 1679 by Papin.
contextual, as are air brakes 'failing closed'. However, I wonder how fast Papin made his spagbol with his pressure cooker
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replyAssuming the guy is for real (the closest relation I have to EE is accidentally electrocuting myself at times), I'm pretty sure they're referring to circuits breaking open or remaining closed, hence the opposite meaning.
replyTook me a minute as well, cause indeed with a computer background, the meaning is completely the opposite. Just like in other security contexts (door locks).
The ambiguity is a good reason to avoid the expression entirely.
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