If you use thermal fuses in your work, then you’re no doubt familiar with the series of letters, numbers, and symbols printed on the sides of the fuse body. If you know how to read these markings you can learn a wealth of information about that particular thermal cutoff fuse. In this quick guide, we’ll show you how to read the markings on SEFUSE and Elcut thermal cutoffs.
Understanding the Markings on SEFUSE Brand Thermal Cutoffs…
Let’s start with SEFUSE’s axial fuses, the SF/E and SF/R series manufactured by NEC/SCHOTT. Unlike Elcut brand thermal fuses, the SEFUSE cutoffs begin with the full brand name at the top followed by a series of letters, numbers, and symbols.
In descending order on the SF/E and SF/R thermal cutoffs, these markings tell you:
- Brand name
- Part number
- Rated functioning temperature. On the E series, the rated functioning temperature is preceded with the JET marking.
- Rated current, sometimes preceded by the letters PSE (mark of Electrical Appliance and Material safety law in Japan), but only on the E series. On the SF/R, PSE markings are removed and the rated voltage can be found on the packaging.
- On the E series, the CCC mark followed by the rated voltage. On the R series, the rated current.
- A black line followed by the factory code and lot number (the first two digits of the lot number are the year, followed by the month, followed by a sub-lot number)
Reading the Markings on Elcut brand TCOs
On Elcut’s line of radial and axial TCOs manufactured by Uchihashi Estec, you’ll find the following information in descending order:
- Type number followed by an abbreviation of the company name
- The rated current followed by the rated functioning temperature
- The rated voltage followed by an AC mark and two capital letters that represent the date code
- PSE mark and any third party approval
Final Thoughts on TCO Markings, Ratings, and Safety: Why It’s Crucial To Always Use Thermal Fuses Properly
Here in the U.S., foreign-headquartered corporations like Uchihashi Estec and NEC/SCHOTT invest $750 billion in the manufacturing industry each year and employ more than 1.6 million people. Even though U.S. manufacturing companies still produce almost half of the nation’s exports, the industry has been stifled in recent decades. That’s because these companies face 20% higher structural costs (taxes, employee benefits, tort litigation, etc.) compared to other trading partners. Despite this, U.S. manufacturers still have a reputation for producing reliable, high-quality goods and parts.
Thermal fuses provide a crucial safeguard in many of these items, but only if used properly. Before you use thermal fuses, always double check the markings on the fuse body and/or packaging and follow the manufacturer’s installation instructions and cautions.
Remember: All of the electrical ratings, rating agency approvals, and technical specifications may not be listed on the TCO body because of space limitations. For complete specifications, always refer to the manufacturer’s catalog.