Hello John, Others can probably provide a better answer than I can, but I'll make an attempt.
Fuses and circuit breakers are extremely safety-critical. The Listed overcurrent protectors are typically for building power distribution. Long ago, replacing blown fuses was a common task for a homeowner. The fuses had to be designed to a higher level of safety because the installation was somewhat uncontrolled. The Listed versions are tested to a level where it acceptable for handling by general users rather than by instructed or trained personnel. The Listed overcurrent protectors should fail gracefully with high currents from ground faults. Recognized overcurrent protectors are generally not acceptable for branch circuit protection where they could be reset or replaced by a general uses. UL has different standards for Molded Case Circuit Breakers and Supplementary Overcurrent Protectors, with the latter often being the Recognized components. As the standard name implies, they supplement the branch circuit protection and do not replace it. Recognized fuses may often ben internal to a device where they are within a fire enclosure and only accessible to service personnel. This is a bit of an oversimplification, but I hope it helps clear it up a little. Regards, Ted Eckert The opinions expressed do not necessarily reflect those of my employer or UL. From: John Allen <[email protected]> Sent: Monday, May 11, 2020 11:19 AM To: [email protected] Subject: [EXTERNAL] [PSES] UL Listed Fuse vs Recognized Hi, I hope everyone is good, healthy and being safe. Does anyone have an accurate explanation of how a fuse can be UL Listed vs UR? A fuse cannot stand alone as with other UL Listed products. UL categories are JDYX, JDYX2 Thank you and Be Safe, John - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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