Regarding the standards for low voltage fuses, the more influential ones in the international are IEC standard and UL standard, and the main standards in Asia are CCC of China and METI of Japan . Each standard for the fuse time, current characteristics of the definition is not exactly the same, so these standards of the fuse is not arbitrarily interchangeable. Because of the different standards for fuses, it is very important for circuit designers to pay attention to the use of fuses of different international standards.

Many countries around the world adopt the IEC standard, while some countries in North America adopt the UL standard. The current UL standard for low voltage fuses is drafted and revised by the relevant departments of the United States, Canada and Mexico, and has become a common standard for the three countries mentioned above. In order to promote trade and enhance communication, it is necessary to study the UL standard and its differences with the IEC standard.

At present, UL and IEC in the low-voltage fuse standards have the phenomenon of mutual penetration. For example, the IEC will be UL’s class J and L fuse into the IEC60269-2-1 standard, while UL will fuse the definition of the provisions of the corresponding provisions of the IEC number. Nevertheless, in the standard system and the technical requirements of the standard, there are still some differences between the two standards.

IEC on low-voltage fuse published a total of 7 product standards, standard series number for IEC60269. UL low-voltage fuse standard has 16, standard series number for UL248. which UL248-1 standard name and IEC60269-1 standard name security consistent.

Scope of application
(1) voltage range, IEC fuse voltage limit AC 1kV, DC 1.5kV, UL AC and DC voltage limit are 1kV. compared with the two, IEC DC fuse range is wider.

(2) Miniature fuse. Miniature fuse voltage is generally lower, roughly in 250V and below, should belong to the category of low-voltage fuse. However, due to the IEC’s TC32 “fuse” Technical Committee is divided into three sub-technical committees: SC32A “high-voltage fuses”, SC32B “low-voltage fuses” and SC32B is responsible for the IEC60269 series of standards for low voltage fuses, which are not applicable to miniature fuses. The technical requirements for miniature fuses are included in the IEC 60127 series of standards governed by SC32C. UL does not specify in the scope whether miniature fuses are applicable, but includes miniature fuses in the definitions below and in specific product standards. For example, in UL 248-14, Auxiliary Fuses, the minimum breaking capacity of miniature fuses is specified as 50A.

(3) Breaking capacity: IEC specifies the lower limit, i.e., the minimum breaking capacity of the fuse is 6kA, and the upper limit is not specified. UL specifies the upper limit, i.e., the maximum breaking capacity of the fuse is 200kA, and the lower limit is not specified.