UL 5085-2-2021 pdf download – Low Voltage Transformers – Part 2: General Purpose Transformers.
5 Mechanical Assembly 5.4 A transformer weighing more than 45 kg (100 lbs) shall be provided with a means for lifting by a forklift, cable, sling, or similar method. The lifting means may be provided on the transformer core or frame if the transformer has a removable top cover. The lifting means shall be subjected to the Lifting or Mounting Means Test in Clause 37. Note: The lifting means test does not apply to a transformer that is intended to be lifted from underneath by a forklift or other method. 6 Enclosure 6.5 Openings 6.5.2 Openings shall prevent passage of a straight rod 12.7 mm (0.5 inch) in diameter. When the distance between live parts and the enclosure and between the plane of the ventilation opening and live parts is 102 mm (4 inches) or more, openings shall be constructed so that they will prevent passage of a rod 19 mm (0.75 inch) in diameter. When the distance between the plane of the opening and uninsulated live parts is less than 102 mm (4 inches), the rod shall have a cross-section of 13.4 mm (0.53 inch). 8 Connections 8.1 General 8.1.4 A transformer shall have provision for the connection of supply and load conductors, either in the form of busbars, leads, pressure terminal connectors, or terminal pads for pressure terminal connectors. Note: Studs or wire binding screws may be used for field connections when the full load current of the terminal is 24 A or less and the transformer is marked in accordance with Clause 17.5.5. The studs or wire binding screws may be used for the field connection of 5.3 mm 2 (10 AWG) or smaller conductors. 8.4 Pressure terminal connectors 8.4.5 More than one wire connector may be provided for a single connection point to allow for connection of the various size conductors which require accommodation. In such case, each connector shall be marked in accordance with Clause 17.5.7. 8.5 Leads 8.5.9 A transformer lead shall: a) Be of stranded wire. b) Not be smaller than 2.1 mm 2 (14 AWG) copper or 3.3 mm 2 (12 AWG) aluminum.