UL 291:2001 pdf download – Automated Teller Systems.
8 Internal Wiring
8.1 General
81.1 Internal wiring shall have insulation rated br the potential involved and the temperatures to which it may be subjected. The wiring shall be routed away from moving parts and sharp prnjections and held in place with clamps. string ties, or equivalent means, unless it is of sufficient rigidity to retain a shape form. Conductors that are used for grounding do not require insulation unless needed for identification.
8.1.2 Leads oi- a cable assembly connected to parts mounted on hinged covers or moving parts shall be flexible and of sufficient length to permit the lull opening of the cover without applying stress to the leads or their connections. The leads shall be secured or equivalently arranged to prevent abrasion of insulation and jamming between parts of the enclosure.
8.1.3 If the use of a short length of insulated conductor is not feasible (for example, short coil lead or the like), electrical insulating tubing may be used. The tubing is not to be subjected to sharp bends, tension. compression, or repeated flexing, and is not to contact sharp edges, projections. or corners. The wall thickness shall conform to the requirements for such tubing, except that for smaller sizes ob polyvinyl chloride tubing. 318-inch (9.5-mm) or less, the wall thickness at any point shall not be less than 0.017 inch (0.43 mm). For insulating tubing of other types. the thickness shall not be less than that required to provide the required mechanical strength, dielectric properties, heat- and moisture-resistant characteristics at least equal to 0.107-inch thick polyvinyl chloride tubing.
8.1.4 Internal wiring of circuits which operate at different potentials shall be separated by barriers, clamps. routing, or other means determined to be equivalent unless all conductors are provided with insulation which is rated for the highest potential and temperature involved.
8.1.5 Stranded conductor clamped under wire binding screws or similar parts shall have the individual strands soldered together or equivalently arranged.
8.2 Barriers
8.2.1 If a barrier of insulating material is used to separate wiring, It shall not be less than 0.028 Inch (0.71 mm) thick and shall be of thickness sufficient to ensure that movement of the wires during servicing or normal product operation will not deform the barrier and reduce the separation. Any clearance between the edge of a barrier and a compartment wall shall not be more than 1/16 inch (1.6 mm),
8.6 Strain relief
8.6.1 A strain relief means shajl be povided for internal wires or wire harnesses and cables which are subject to movement in conjunction with the operation or servicing of any product to prevent the transmission ol stress to terminals, connections, or components. Movement of conductors provided with a metal ring type of strain relief shall not damage connections or components.
9 Bonding for Grounding
9.1 Exposed noncurrent carrying metal parts likely to become energized shall be bonded to the point of connection of the field equipment grounding terminal or lead and to the metal surrounding the knockout, hole, or bushing provided for field power supply connections.
9.2 Uninsulated metal parts of cabinets, electrical enclosures, and mounting brackets, capacitors, and other electrical components likely to become energized are to be bonded if they may be contacted by the user or by service personnel in servicing the equment.
9.3 A bonding conductor shall be of material determined to be acceptable for use as an electrical conductor. If of ferrous metal, it shall be protected against corrosion by painting, plating. or the equivalent. The conductor shall have the current carrying capacity of the maximum size wire used in the circuit wiring of the component or part, and shall be installed so that it is protected from mechanical damage.
9.4 The bonding shall be by a positive means, such as clamping, riveting, bolted or screwed connection, brazing. or welding. The bonding connection shall reliably penetrate nonconductive coatings such as paint. Bonding around a resilient mount shall not depend on the clamping action of rubber or similar material.
9.5 A bolted or screwed connection that incorporates a star washer under the screwhead may be used for penetrating non•conductive coatings where required for compliance with 9.4.