There is a lot of confusion regarding the terminology, definitions and tests/standards related to optional markings commonly used and /or claims associated with specialty cables. For example, what do "LSZH" (Low Smoke Zero Halogen Free), "Non-Halogen", "Halogen-free", "Low Smoke", "HFFR" (halogen-free, flame retardant), "LSF0H" (low smoke and fume, zero halogen), "LSF" (low smoke and fume), "LSNH" (low smoke non-halogen), "LSHF" (low smoke halogen-free), "LS0H" (low smoke zero halogen), "0HLS" (zero halogen low smoke), "NHFR" (non-halogen, flame retardant), "HF" (halogen-free), "LS" (low/ limited smoke), "FRLS" (fire resistant, low smoke) and "LH" (low halogen) mean?
A few years ago the IEC developed requirements around the term Low Smoke Halogen Free (LSHF) as described in IEC 62821-1/-2/-3. The requirements in this IEC standard series describe methods to determine the halogen content in all combustible materials used in the construction of a cable, the smoke generation of the entire cable and most importantly a cable surface Mark directly linked to these test methods, as described in the IEC standard.
Since the release of the IEC standard, UL has developed our HF and LSHF material Recognition and cable Mark Certification programs, respectively. Material suppliers and cable manufacturers now can apply standards-based surface print marking which attests to compliance with these requirements, backed by the globally trusted UL Mark.
The inclusion of the optional HF and LSHF markings in various Articles in 2020 the National Electrical Code (NEC), recognize the widespread use and importance of such markings in conveying relevant information about cable properties to installers and AHJs. Halogen-free materials are taking on increasing importance in specialty installations involving spaces with reduced ventilation capabilities such as elevators, subways, mines and the like. Internationally, there is an increasing number of regulations restricting the use of halogenated materials, resulting in the growing use of halogen-free cables and their associated markings.
As a result, the NEC has included the "halogen-free" and "low smoke halogen-free" surface marking definitions in Articles 725 & 805 with applicable test standards in the 2020 edition.
As indicated in Article 725.179, Paragraph K, Optional Markings – "Some examples of optional markings are ST1 to indicate limited smoke characteristics in accordance with UL2556, Wire & cable test methods, HF to indicate halogen-free as described in UL 2885, Outline of Investigation for Acid Gas, Acidity and Conductivity of Combusted Materials, and LSHF to indicate Low Smoke and Halogen Free characteristics in accordance with IEC 61034-2, Measurement of smoke density of cables burning under defined conditions – Part 2: Test procedure and requirements."
The addition of applicable surface marking terminology avoids misuse and misrepresenting cable markings and performance. These examples clearly define the performance criteria that the products have been evaluated.
The proper use of appropriately marked and certified specialty cables help enhances safety and reduces misinformation/misuse.