me_chkaa：
据我所知,UL的标准里,关于enclosure的要求,都统一跟从UL746C(可能一些与IEC合并的标准例外).根据UL746C,凡>42.4Vpeakvoltage(30VRMS)的电压都视为可能导致着火或触电.3.34RISKOFELECTRICSHOCK–Ariskofelectricshockisconsideredtoexistatanypartif,a)Thepotentialbetweenthepartandearthgroundoranyotheraccessiblepartismorethan42.4Vpeak,andb)Thecontinuouscurrentflowthrougha1500ohmresistorconnectedacrossthepotentialexceeds0.5mA.3.35RISKOFFIRE–Ariskoffireisconsideredtoexistatanytwopointsinacircuitwhere;a)Theopencircuitvoltageismorethan42.4Vpeakandtheenergyavailabletothecircuitunderanyconditionofloadincludingshortcircuit,resultsinacurrentof8Aormoreafter1minuteofoperation,orb)Apowerofmorethan15wattscanbedeliveredintoanexternalresistorconnectedbetweenthetwopoints.