Subject 8750 safety evaluation and test

Supplementary to the above standards are Subject 8750, now in its third edition and with 12 chapters. Chapters 1-4 cover scope and definitions, Chapters 5-9 construction, Chapters 10-11 tests and evaluation, and Chapter 12 markings. The rest of this article will focus specifically on “construction” and “tests and evaluation”. However, as the application and environmental location, and thus safety requirements of each product vary, different clauses in Subject 8750 may apply to different products.

1. Construction (Chapters 5-9)

1. Environmental considerations: Safety requirements, with regard to spacing of electrical parts, plastic enclosure, testing and markings, vary according to the environmental location, e.g., dry, damp or wet.

2. Mechanical construction: This chapter specifies the safety requirements for the enclosures with emphasis on protection against fire, electric shock and impact. It also covers the requirements for the thickness of metal enclosures, anti-corrosion performance and physical properties of plastic enclosures as well as requirements for barriers, conductor protection, strain relief and potting compound.

3. Electrical construction: This includes accessibility of hazardous live parts, exposed wiring terminals, internal wiring, supply and load connections, separation of circuits, insulating materials, specifications for printed wiring boards, spacing of electrical parts, circuit components, protective devices, and restrictions of energy to Class 2 and LPS safety circuits.

4. Other areas: This section covers the safety requirements for LED power source, LED arrays, LED modules and LED control modules and their enclosures. The power source can be any of the UL 1012, UL 1310 and UL 60950-1 certified power supplies. In principle, if an LED array, LED module or LED control module is located at an LPS/Class 2 safety circuit, there is no requirement for an enclosure. Basic insulation is required for isolated output type, same for the direct type. It is recommended that if the energy consumption of the LED array, LED module and LED control module does not exceed the load limit (See Table 7.2 & Table 7.3) of the LPS/Class 2 circuit, LPS/Class 2 standards output should be adopted. If the energy consumption exceeds the load of the LPS/Class 2 circuit, the requirements on the plastic enclosure are the same regardless whether insulation is provided to isolate the primary circuit and secondary circuit.

Testing and evaluation (Chapters 10-11)

In this section of Subject 8750, the tests performed by UL include input test, LED module normal operations temperature test, dielectric voltage withstand test, abnormal condition test, unreliable component abnormal test, 50-W point power measurement test, etc.

Latest Category Code Numbers (CCN) for lighting products

In view of the ever increasing applications of LED lighting, this year UL added and defined a number of new CCNs, e.g. OOQA2 (LED modules, UL 8750), FKSZ (LED drivers, UL 935), OOLV (LED self-ballasted lamps, UL 1993), QOVZ (portable LED lights, UL 153), QOVA (LED cabinet lights, UL 153), IFAM (fixed LED lighting, UL 1598), IFAO (LED down lights, UL1598), etc. Manufacturers may apply for different UL certifications according to the CCNs. Definitions of the two CCNs (OOQA2 and FKSZ) concerning manufacturers most are illustrated in the table below:

Issues such as low luminous efficiency and limitations on heat dissipation are yet to be overcome in the applications of LEDs in lighting products. Nevertheless, with increasing demand for higher energy efficiency, LED lighting offers a promising prospect. In this development stage of safety standards for LED lighting products, manufacturers can enhance competitiveness of their products by proactively incorporating safety considerations in product research and development and keeping a close eye on news about product testing requirements in the international market. For more information and news about UL safety standards for LED, contact your local UL customer service team.

by Michael H. Lai, Conformity Assessment Services, Taiwan

Know more about:

• Lighting applications of LED Lights, Safety requirements for LED lighting products, Classification of LED lighting products according to UL Standards
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