UL 1564-2020 pdf download.STANDARD FOR SAFETY Industrial Battery Chargers.
6.7 The diameter of the wires of a screen shall not be less than 0.0598 inch (1.519 mm) if the screen openings are 112 square inch (3.2 cm2) or less in area and shall not be less than 0.100 inch (2.54 mm) for larger screen openings.
6.8 Perforated sheet steel and sheet steel used for expanded metal mesh shall not be less than 0.042
inch (1.07 mm) thick, 0.058 Inch (1.47 mm) thick if nonferrous, if the mesh openings or perforations are 1/2
square inch (3.2 cm2) or less in area, and shall not be less than 0.080 inch (2.03 mm) thick, 0.112 inch
(284 mm) thick if non-ferrous, for larger openings.
Exception: In a small charger where the indentation of a guard or enclosure does not affect the clearance between uninsulated, movable, current-carrying parts and grounded metal, 0.020 inch (0.51 mm) steel or 0.029 inch (0.74 mm) nonferrous expanded metal mesh may be employed, provided that:
a) The exposed mesh on any one side or surface of the battery charger that is so protected has an area of 72 square inches (465 cm2) or less and does not have any dimension greater than 12 inches (305 mm); or
b) The width of the protected opening is 3-1/2 inches (88.9 mm) or less.
6.9 If an electrical instrument, such as a meter, forms part of the enclosure, the face or the back of the instrument housing, or both together, shall comply with the requirements for an enclosure.
Exception No. 1: This requirement does not apply to an electr,cal instrument connected in a secondary circuit where damage to or deterioration of the materials of which the housing is made does not result in a risk of fire or electric shock.
Exception No. 2: This requirement does not apply to a meter complying with the Standard for Electrical Analog Instruments — Panel Board Types, UL 1437.
6.10 Material supporting terminals or used as internal electrical insulation of an electrical instrument shall comply with the requirements in Insulating Materials, Section 15. The acceptability of spacings between live and dead metal parts connected to the enclosure within the instrument shall be determined by compliance with the requirements in 32.1.1.
Exception No. 1: This requirement does not apply to an electrical instrument connected in a secondary circuit where damage to or deterioration of the materials does not result in a risk of fire or electric shock.
Exception No. 2: This requirement does not apply to a meter complying with the Standard for Electrical Analog Instruments — Panel Board Types, UL 1437.
6.11 Supporting feet of a product that form part of the enclosure or are needed for ventilation shall be reliably secured and the aging, physical, and flammability properties of the material shall be investigated. The effect of oil and the absorption of moisture on the mounting feet are also to be considered.
Exception: Supporting feet may be accepted without testing if they do not form part of the enclosure and are not needed to provide ventilation.
6.12 An enclosure, frame, or cover of a material other than sheet metal shall provide protection equivalent to that required by 64.
6.13 Among the factors taken into consideration when judging the acceptability of a nonmetallic enclosure are:
a) Mechanical strength;UL 1564 pdf download.