UL 20 STANDARD FOR SAFETY General-Use Snap Switches
UL 20 STANDARD FOR SAFETY General-Use Snap Switches
1 Scope
1.1The requirements of this Standard apply to manually operated,general-use snap switches forconnection to copper(Cu) or copper-clad conductors used in accordance with the National Electrical Code(NEC)，ANSI/NFPA 70,or the Canadian Electrical Code (CE Code),Part l, and intended to bepermanently connected in accordance with the NEC and the CE Code, Part l. In Canada, requirements forswitches for connection to aluminum(Al) conductors used in accordance with the CE Code, Part l, andintended for connection to wiring systems recognized by the CE Code, Part l, are covered in AnnexB
1.2This Standard applies to acldc rated switches for which the load ratings do not exceed 60 A at 250vor less,30 A at 251V-600 v, and 2 hp at 125V- 600 V or less. This Standard also covers ac-only ratedswitches for which the load ratings do not exceed 30 A at 347 VAC or less.
1.3 This Standard applies to switches constructed to be installed readily in a flush device box or on anoutlet-box cover and intended for connection to branch-circuit wiring.
1.4 This Standard applies to pendant and through-cord switches intended for field installation on flexiblecord and provided with one "on" and one "off" position.
1.5 This Standard applies to switches intended for surface mounting and provided with a separable baseand cover for connection to exposed wiring consisting of nonmetallic sheathed cable or open wiring oninsulators (knob and tube).
1.6 This Standard applies to self-contained switches intended for flush mounting without a separateoutlet box and for connection to branch-circuit wiring consisting of one or more non-metallic sheathedcables containing copper conductors.
1.7 This Standard applies to ac/dc fixture switches intended to be installed in fixtures to controlincandescent lighting or fans for connection to branch-circuit wiring.
1.8 This Standard also applies to single-pole，momentary-contact door switches constructed to beinstalled readily in a special-purpose device box or on an outlet-box cover for connection to branch-circuitwiring.
1.9This Standard does not apply to:
a) Clock operated switches specified in the Standard for Clock-Operated Switches, UL 917, andCsA Standard C22.2 No.177;
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