UL 469:2006 pdf download – Musical Instruments and Accessories.
27.2 Nonhazardous secondary circuits
27.2.1 A nonhazardous secondary circuit is considered to exist if the source of power to the circuit is not capable of:
a) Producing an open-circuit voltage exceeding:
1) 30 volts AC or 60 volts DC where wet contact is not likely to occur and
2) 21] volts peak where wet contact is likely to occur (see 11.2): and
b) Delivenng a power of more than 15 watts into an external resistor connected singly between each of these points and any return to the power supply.
27.2.2 An overcurrent-potective device may be used to limit the available power in a circuit to 15 watts or less in order to comply with 27.2.1(b).
27.2.3 A printed-wiring board shall comply with the applicable requirements in Table 7,1, and winng not segregated routed away from wiring located in hazardous energy circuits or low-voltage, limited-energy circuits shall be rated VW- 1.
27.2.4 There are no addihonal specifications for insulating material, spacings, and components in a nonhazardous secondary circuit other than as may be required to prevent contact with an uninsulated live part of another circuit,
28 Scope
28.1 The requirements in Protection Against Injury to Persons, General, Section 29; Power-Operated Moving Parts, Sechon 30: Enclosures and Guards. Section 31; and Sharp Edges, Section 32; are applicable to products covered by this standard that may involve a risk of injury to persons in normal operation.
28.2 There are risks of injury to persons inherent in some products that. if completely eliminated, would defeat the utility of the product. The requirements In Sections 29 — 32 are intended to reduce such risks, while retaining the normal function of such a product.
29 General
29.1 If operation, maintenance. or reasonably foreseeable misuse of a product by the user involves a risk of injury to persons. protechon shall be provided for the reduction of such ask.
29.2 Among the factors to be considered in evaluating the acceptability of an exposed moving part are:
a) Degree of exposure necessary to perform its intended function,
b) Sharpness of the moving part,
C) Risk of unintentional contact therewith.
d) Speed of the moving part, and
e) Risk that a part of the body would be endangered or that dothing would be entangled by the moving part.
These tactors are to be considered with respect to both intended operation of the product and its reasonably foreseeable misuse.
29.3 The acceptability of a guard, a safety release, an interlock, or the like, and whether or not such a device is required. are to be determined from a study of the complete product. its operating characteristics, and the likelihood of a risk of injury to persons resulting from a cause other than gross negligence. The investigation is to indude consideration of the results of breakdown or malfunction of any one component; but not more than one component at a time, unless one event contributes to another. If the study shows that malfunction of a particular component can result in a risk of injury to persons, that component is to be investigated for reliability.
29.4 A product shall be subjected to the tests described in this section and the Strength of Enclosure Tests, Section 55, to determine compliance with the requirement in 29.1.
30 Power-Operated MovIng Parts
30.1 The accessibility of a power-operated moving part, such as a gear or linkage, is to be judged by the applicable accessibility requirements in 10.1,1 — 10-3.1. The accessibility requirements are to be applied after the installation or assembly of parts provided by the manufacturer has been completed in accordance with the instructions provided by the manufacturer.
Exception: The requirement does not apply to a tape reel, a tape-drive mechanism or a piano-roll-drive mechanism that must be exposed for intended use. However, a gear or linkage is to be juded for accessibility if the construction permits that part to move with a tape reel, cartridge, cassette, or piano roll removed from its operating position.