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For the wire insulation located within 13 mm from an arcing PIS at the terminal of an insulated wire used in a mains PS3 circuit, I have a question on separation of combustible materials from a PIS and requirements for internal wiring.

More specifically you asked: IEC/EN 62368-1:2014 Question An insulated wire in a mains PS3 circuit is connected to a terminal within a product, the connection point being an arcing PIS. The terminal complies with the relevant IEC component standard. The wire insulation (combustible material) will be within 13mm of the PIS. Regarding compliance with clause 6.4.7, is the above scenario acceptable on the basis that the wire insulation is "the material on which the PIS is mounted" or because the wire insulation complies with the flammability requirements of "the relevant IEC component standard" as specified in clause 6.5.1?  Is this any different in edition 3?  If VW-1 rated sleeving is used within 13mm of the PIS, will either edition allow?


As required by of IEC 62368-1:2018, a supplementary safeguard is required to control the spread of fire from any possible PIS to other parts of the equipment as given below, including,

  printed boards shall be made of V-1 class material or VTM-1 class material; and

  wire insulation and tubing shall comply with 6.5.1.


Per subclause 6.5.1,  insulated wire is acceptable if it complies with the recommended performance requirements of the applicable IEC 60332 standards, or with the requirements of IEC/TS 60695-11-21.


In IEC 62368-1:2018, a new note has been provided “Wire complying with UL 2556 VW-1 is considered to comply with these requirements.”  This note was added because the UL 2556 VW-1 flame testing is similar to IEC 60695-11-21.  Therefore, UL 2556 VW-1 should be able to be used both for Edition No.2 and Edition No. 3 of IEC 62368-1.


Also, please note, wiring and cables insulated with PVC, TFE, PTFE, FEP, polychloroprene or polyimide remain acceptable during the transition according to subclause 4.1.1 of IEC TR 62368-2 (Explanatory information related to IEC 62368-1).  However, once 4.1.1. is removed from IEC 62368-1, this consideration no longer will be permitted.

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