Does UL plan to publish a UL 62368-3 Standard based on IEC 62368-3:2017?
For those unaware, the first edition of IEC 62368-3 was published in 2017, and has the title, “Audio/video, information and communication technology equipment - Part 3: Safety aspects for DC power transfer through communication cables and ports.” It addresses two key topics.
Its Clause 5 covers power transfer using ES1 and ES2 voltages. USB and PoE are examples of the technologies covered.
Its Clause 5 covers power transfer using RFT, or Remote (Power) Feeding Telecommunications circuits. Clause 6 essentially covers the same circuits / technologies as originally covered in the legacy standard, IEC 60950-21, Remote Power Feeding.
For more background on IEC 62368-3, please review UL’s IEC 62368-3 Backgrounder, available via the 62368-1 UL Toolkit - https://62368-ul-solutions.com/toolkit.html .
When the CAN / US Technical Harmonization Committee (THC) reviewed both IEC 62368-1:2018 and IEC 62368-3:2017 for potential adoption in Canada and the U.S., a decision was made to develop and propose a CAN / US version of the latest IEC 62368-1 standard, which subsequently was published on December 13, 2019 as CSA / UL 62368-1:2019 (Ed. No. 3). However, during this review the THC also made a decision not to pursue a CAN / US version of IEC 62368-3.
The decision not to pursue a CAN / US version of IEC 62368-3 was made because the THC believed IEC 62368-3 requires some refinement before it would be an appropriate standard for adoption as a mandatory bi-national standard for Canada and the U.S. This refinement was thought needed both for its Clause 5 and its Clause 6. Therefore, rather than adopt IEC 62368-3, the THC proposed, and eventually got accepted the following National Difference in Clause 1 of CSA / UL 62368-1, Ed. No. 3.
“1DV.2.3 Additional requirements for equipment with DC power transfer through communication cables and ports are given in IEC 62368-3. IEC 62368-3 clause 5 for DC power transfer at ES1 or ES2 voltage levels is considered informative. IEC 62368-3 clause 6 for remote power feeding telecommunication (RFT) circuits is considered normative (see ITU K.50). Alternatively, equipment with RFT circuits are given in either UL 2391 or CSA/UL 60950-21. RFT-C circuits are not permitted unless the RFT-C circuit complies with RFT-V limits (≤ 200V per conductor to earth).”
Therefore in Canada and the U.S., USB, PoE and similar circuits will not be required to be investigated to Clause 5 (in addition to 62368-1). However, RFT circuits will continue to need additional evaluation beyond 62368-1 per the options allowed for in the National Difference 1DV.2.3.
We should also point out that Europe is in the process of adopting an EN / IEC 62368-3 standard, likely to be published in 1Q 2020. Therefore, for AV / ICT products with DC power transfer intended for European markets, EN / IEC 62368-3 will be required, including the requirements in Clause 5 when applicable.