Relation to UL
UL 2011 is the UL standard that applies to industrial machinery and equipment in the United States. It is intended to ensure that machinery and equipment comply with the fire safety requirements specified by OSHA. In addition, the standard defines the test procedures used to verify compliance with these requirements. With regard to the control cabinets used, UL 2011 refers to control cabinet-specific standards, such as UL 508A.
What does UL 2011 mean?
UL 2011 is a standard established by Underwriters Laboratories designed to ensure that industrial machinery complies with the requirements set by the Occupational Safety and Health Administration (OSHA) regarding the prevention of fires and electric shocks. If the machine in question is to be operated in a potentially explosive atmosphere, explosion protection requirements also apply. To this end, the standard defines certain minimum safety requirements for electrically powered machinery. In addition, the UL 2011 standard naturally specifies the tests that must be conducted to verify compliance with these standards.
Structure of UL 2011
UL 2011 is divided into three parts. Part 1 specifies the general electrical safety requirements for industrial machinery, such as requirements for design features, internal and external wiring, labeling, and documentation.
Part 2 of the standard specifies the requirements for specialized industrial machinery (e.g., machine tools, automated assembly machines, packaging machines), industrial additive manufacturing systems (so-called 3D printers), and semiconductor manufacturing equipment. To this end, the general requirements from Part 1 serve as the basis and are supplemented, qualified, and/or modified accordingly.
Part 3 of UL 2011 addresses machinery used in potentially explosive atmospheres. Additional specific requirements for certain types of machinery and standards referenced in connection with UL 2011 are covered in Appendices A through D and FS .
Scope of UL 2011
UL 2011 defines an industrial machine as a machine that is not intended to be moved by hand during operation, but is power-driven or automated and processes the material by cutting, shaping, laminating it, or applying pressure, electrical, thermal, or optical processes—or a combination of these methods—to it. Specific examples include metalworking, food processing, and textile machinery, as well as compressors. UL 2011 may also cover equipment that is only indirectly involved in these processing operations, such as equipment that transports material to or from a machine or is used for testing or packaging the processed material. All of the machine’s electrical equipment and associated software are also covered by UL 2011, as they are considered part of the system.
Like all UL standards, adoption of UL 2011 is not mandatory for local authorities (Authorities Having Jurisdiction, AHJs) in the United States. The AHJs may impose requirements that are more stringent or different from those defined in UL 2011. However, for several years now, there have been efforts to harmonize the remaining regional differences in line with UL 2011.
How is compliance with UL 2011 verified?
To ensure that a machine meets the requirements of UL 2011, the standard specifies a series of standardized tests and verifications. The ability to meet these requirements is referred to as “performance.” These tests and verifications include, among others, a temperature test/calculation, a dielectric strength test/calculation, a test of all emergency stop and other safety devices, a residual voltage test, and a resistance measurement. The specific requirements that must be met in these tests are either defined in UL 2011 itself or refer to the specifications of the UL 508A standard for industrial control equipment.
Important to note: Testing a machine in accordance with UL Standard 2011 applies only to potential risks from fire, electric shock, and explosion hazards. Other requirements set by OSHA or the AHJ, such as maximum permissible noise levels or similar criteria, are not part of a UL evaluation and must therefore be addressed separately with the relevant authority.
Proof of Compliance with UL 2011
Underwriters Laboratories is a Nationally Recognized Testing Laboratory (NRTL), meaning it is an accredited and certified testing laboratory authorized to conduct evaluations and tests on industrial machinery. To this end, UL develops its own standards in accordance with the requirements of OSHA and the National Electrical Code (NEC). If a machine meets the requirements specified in the relevant UL standard, it can receive a corresponding UL mark from UL. This mark, in turn, facilitates approval by the local AHJ, as the AHJ can immediately recognize that the machine in question meets the requirements of UL 2011.
Zusammenfassung
As a standard for industrial machinery and equipment, UL 2011 defines the applicable fire safety requirements, as well as test procedures to verify compliance with them. Part 1 defines general requirements; Part 2 of UL 2011 addresses specific types of industrial machinery; and Part 3 contains specifications for industrial machinery used in potentially explosive atmospheres. According to UL 2011, an industrial machine is defined as a machine that operates automatically and is not manually operated during operation. If it meets all the requirements of UL 2011, this is referred to as “performance”; the machine can then receive a corresponding UL certificate after testing by an NRTL. This significantly facilitates approval by the local AHJ.
