UL 3730-2021 pdf download – Photovoltaic Junction Boxes.
4.2.3 With reference to paragraph 7.2 (d) of the Standard for Flat-Plate Photovoltaic Modules and Panes, UL 1703, a polymeric material serving as the support or insulation of a live part as defined in Standard for Polymeric Materials – Use in Electrical Equipment Evaluations, UL 746C, Table 6.1, shall have an Inclined Plane Tracking (ASTM D2303) rating of 1 hour using the time to track method at the higher of system voltage or 1000 V when the system voltage is in the range of 601 – 1000 Vas specified in Table 4.1. Exception No. 1: The 1 hrrating is not required fora polymeric material serving as the support orinsulation of a live part as defined in UL 746C, Table 6.1, when both the material and live part are completely encapsulated by a potting material such there is no surface upon which tracking may occur, and the potting material has been evaluated according to UL 746C, Table 6.1, for Electric Strength, Resistance to Electrical Ignition Sources (HAI and HWI), and Thermal Endurance. Exception No. 2: The 1 hr rating is not required for a polymeric material serving as the support or insulation of a live part as defined in UL 746C, Table 6.1, when both the material and live part are completely coated by a conformal coating that has been evaluated to the requirements of UL 746C, Section 43, at the rated thickness such that there is no surface upon which tracking mayoccur. Exception No. 3: Silicone based RTV when applied in accordance with Exception No. 2 is considered a suitable potting material without furtherevaluation. 4.2.4 A nonmetallic enclosure intended for connection to a rigid conduit system shall comply with the Polymeric Enclosure Rigid Metallic Conduit Connection Tests in the Standard for Enclosures for Electrical Equipment, UL 50.
4.3 Openings for wiring system connections 4.3.1 Where threads for the connection of conduit are tapped all the way through a hole in an enclosure wall, or where an equivalent construction is employed, there shall not be less than three, or more than five threads in the metal; and the construction of the enclosure shall be such that a conduit bushing is attachable as intended. Where threads for the connection of conduit are not tapped all the way through a hole in an enclosure wall, conduit hub, or a similar component; there shall not be less than 3-1/2 threads in the metal, and there shall be a smooth, rounded inlet hole for the conductors equivalent to that provided by a standard conduit bushing and the hole shall have an internal diameter that corresponds with the applicable trade size of rigid conduit. 4.3.2 Clamps and fasteners for the attachment of conduit, electrical metallic tubing, armored cable, nonmetallic flexible tubing, nonmetallic-sheathed cable, service cable, or equivalent, that are supplied as a part of an enclosure shall comply with the Standard for Conduit, Tubing, and Cable Fittings, UL 514B. 4.3.3 A knockout in a sheet-metal enclosure shall be secured and shall be removable without undue deformation of the enclosure. 4.3.4 A knockout shall be provided with a flat surrounding surface so a conduit bushing of the corresponding size seats as intended. A knockout intended to be used for installation purposes, shall be located so that installation of a bushing does not result in spacings between uninsulated live parts and the bushing of less than required in Spacings, Section 16.