UL 22:2009 pdf download – Amusement and Gaming Machines.
30 Protection Against Risk of Fire, Electric Shock, or Injury to Persons
30.1 General
30.1. if the norrna operation ol an appliance invoives a risk ol fire, electric shock, or injury to persons, means shall be provided to reduce such a risk.
30.1.2 Whether a guard, a safety release, a pressure relief valve, an intedock. or the like is required and whether such a device is adequate shall be determined from an investigation of the complete appliance, its operating characteristics, and the likelihood of a risk of fire, electric shock, or injury to persons resulting from a cause other than gross negligence.
30.1.3 With reference to the requirement in 30.1.2, the degree of protection required of an enclosure depends upon the general construction and intended use of the appliance. The factors to be taken into consideration in evaluating the acceplability of exposed moving parts are:
a) The degree of exposure:
b) The sharpness of the moving parts;
C) The risk of unintentional contact with the moving parts;
d) The speed of movement ot these parts; and
e) The risk of fingers, arms, hair, or clothing being drawn into the moving parts, such as at points where gears mesh or where belts travel onto a pulley or where moving parts dose in a pinching or shearing action.
30.2 Sharp edges
30.2.1 An edge. a projection, a corner, an opening, a frame, a guard, a handle, or the like shall be smooth and not be sufficiently sharp to constitute a risk of injury to persons during intended use or servicing of the appliance.
Exception: This requirement does not apply to a part or portion of a part that is sharp in order to perform a working function.
30.2.2 Whenever referee measurements are necessary to determine if a part as mentioned in 30.2.1 is sufficiently sharp to constitute a risk of injury to persons, the method described in the Standard for Tests for Sharpness of Edges on Equipment, UL 1439. is to be used.
30.3 Interlocks and protective devices
30.3.1 A safety interlock (a means relied upon to prevent access to an area involving a risk of electric shock or injury to persons) shall be of a type or in such a location that it is not likely to be unintentionally operated. In order to bypass a safety interlock, an intentional operation shall be necessary.
30.3.2 An interlock provided for the purpose of protecting personnel against flsk of electric shock shall open all current-carrying conductors of cord-connected appliances and all ungrounded conductors of permanently-connected appliances.
&ception: An interlock switch that opens all current-carrying conductors in the area in which the interlock is intended to provide protection may be used even though conductors outside the protected area are tell
30.3.3 A bypass means shall be such that the safety interlock function is self-restoring when the appliance is returned to intended operation.
30.3.4 A safety interlock operated by a door or panel shall funcbon before any opening resulting from movement of the door or panel is large enough to provide access to parts involving a risk of electnc shock or injury to persons as determined by application of the probes as described in 10.3 and 10.4.
30.3.5 If a safety interlock system is used that employs solid state devices and the performance of the system may be affected by malfunction — either by short Circuit Oi open Circuit — of any single solid state component in the system, the intended use of the system is to include an investgation of that component.
30.3.6 Additional requirements for a safety interlock system are not specified but are to be determined from a study of the entire appliance, its construction. operating characteristics, intended function, and possible misuse. In the case of an interlock system that is not reliable, an investigation of the system and its components is to include consideration of the frequency of operation and the nature of the risk involved in non-operation, and is to include an endurance test based on these factors. In general, the endurance test for interlocks involving service personnel is 6,000 operations and the test for interlocks involving a maintenance person or user is 100.000 operations.