Both UL 489 and UL 1077 are standards for circuit breaker UL certification, and determining which standard applies to a circuit breaker’s UL certification is a key concern for circuit breaker manufacturers. Next, we’ll explain the differences between UL 489 and UL 1077 certifications for circuit breakers. What are UL 489 and UL 1077? UL 489 circuit breakers
Both UL 489 and UL 1077 are standards for UL certification of circuit breakers, and determining which standard applies when applying for UL certification is a major concern for circuit breaker manufacturers. Next, we’ll explain the differences between UL 489 and UL 1077 certifications for circuit breakers.
What are UL 489 and UL 1077?
UL 489 Circuit Breakers
The UL 489 circuit breaker “is intended for installation in a circuit breaker enclosure or as part of other equipment, such as service entrance equipment and distribution panels.” Panel designs often require them, according to the National Electrical Code.
UL 1077 Auxiliary Protector
UL 1077 defines an auxiliary protector as a device used for overcurrent, overvoltage, or undervoltage protection in appliances or other electrical equipment where branch overvoltage protection is already provided or is not required.
Important Note: Although the term “circuit breaker” is used to describe UL 489 and UL 1077 devices, UL 1077 devices are not considered circuit breakers under UL. They are defined as supplemental protectors.
UL Standard Comparison – UL 489 vs. UL 1077
Under the UL program, low-voltage air circuit breakers, molded-case circuit breakers, and miniature circuit breakers are evaluated and “listed” as UL 489 and may be used as stand-alone products.
In contrast, “approved” equipment under UL 1077 (supplementary protectors used in electrical equipment) is evaluated only for use as components within “listed” products.
Compared to “listed” circuit breakers, UL 1077 supplementary protectors are “approved” components. This means that their factory installation within “listed” products (such as UL 508a panels) is subject to inspection.
Both UL 489 and UL 1077 devices must pass a series of calibration, overload, endurance, and short-circuit tests.
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We can provide safety testing, inspection, and certification consulting services in the world’s two major markets—Europe (CE, GS) and North America (UL, ETL)—we can provide testing, inspection, and certification consulting services. Additionally, in accordance with relevant international and national standards, we offer testing and certification consulting services to help mechanical products enter more countries and regions, such as those along the Belt and Road Initiative.
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