UL-751:2012 pdf free download – STANDARD FOR SAFETY Vending Machines.
19 Insulating Material
19.1 Electrical insulation
19.1.1 Porcelain, phenolic composition, or other material acceptable for the application shall be used for the mounting of uninsulated live parts.
19.1.2 Ordinary vulcanized fiber may be used for an insulating bushing, a washer, a separator, and a barrier, but not as the sole support for uninsulated live parts where shrinkage, current leakage, or warpage may introduce a risk of fire or electric shock.
19.1.3 Thermoplastic materials generally are not considered to be acceptable for the sole support of uninsulated live parts, but may be employed if found to have mechanical strength and rigidity, resistance to heat, resistance to flame spread, dielectric strength, and other properties acceptable for the application.
19.1.4 An insulating liner or barrier of vulcanized fiber or similar material employed in lieu of spacings shall not be less than 1/32 inch (0.8 mm) thick, and shall be located or of such material so that it will not be adversely affected by arcing.
Exception No. 1: Vulcanized fiber not less than 1/64 inch (0.4 mm) thick may be used in conjunction with an air spacing of not less than 50 percent of the spacing required for air alone.
Exception No. 2: Insulating material having a thickness less than 1/32 inch may be used if, upon investigation, it is found to be acceptable for the particular application.
19.1.5 A small molded part, such as a brush cap, shall be constructed so as to have the necessary mechanical strength and rigidity to withstand the stresses of actual service. A brush cap shall be secured or located so as to be protected from mechanical damage that might result during intended use.
19.1.6 Electrical insulation that does not comply with 19.1.1 — 19.1.5 shall comply with one of the following:
a) Film-coated wire or materials used in an insulation system that operates at or above Class
105 (Class A) shall comply with the Standard for Systems of Insulating Materials — General, UL
1446. The requirements for film-coated wire or materials used in insulation systems that operate
below Class 105 (Class A) are not specified.
b) Insulating tape shall comply with the Standard for Polyvinyl Chloride, Polyethylene, and Rubber Insulating Tape, UL 510.
c) Insulating sleeving shall comply with the Standard for Coated Electrical Sleeving, UL 1441.
d) Insulating tubing shall comply with the Standard for Extruded Insulating Tubing, UL 224.
19.2 Thermal insulation
19.2.1 Thermal insulating material shall be acceptable for the application. Combustible or electrically-conductive thermal insulation shall not contact an uninsulated live part of the vending machine.
20 Internal Wiring
20.1 General
20.1.1 The wiring and connections between parts within a vending machine shall be protected or enclosed.
20.1.2 With reference to 20.1.1, wiring is considered to be protected if the wiring:
a) Is evaluated as if it were film-coated wire and complies with 14.2 — 14.7; or
b) Conductor insulation is as specified in 20.1 .3 — 20.1 .6.
20.1.3 Other than as specified in 20.1.4, 20.1.5, or 20.1.6, wiring conductor insulation shall be neoprene, thermoplastic or rubber not less than 1/16 inch (1.6 mm) thick for 16 AWG (1.3 mm2 ) and smaller conductors, and 5/64 inch (1.98 mm) thick for 14, 12 or 10 AWG (2.1, 3.3 or 5.3 mm2) conductors.