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For a DC power supply of 48V input, is it necessary to list X capacitors connected across the input in the critical component list (CCL) - if yes then what is the safety aspect of listing them?

In response, since 48Vdc is classified as ES1 when any related tolerances of the supply circuit are less than 60Vdc, the criteria in Table 4 for ES1 would be met. In such a case no further safeguard would be required for such X capacitors, and 5.5.2.1 and G.11 would not apply.  Therefore, such X capacitors should not need to be listed in the CCL in most cases.

 

As there appears to be a specific, detailed construction that needs review / analysis that may not be obvious from the details in the question (e.g., if specified tolerances were greater than 60Vdc, and therefore the requirements and limits in clause 5.5.2.2, Safeguards against capacitor discharge after disconnection of a connector, also may need to be considered), you are encouraged to contact UL for an in-depth consultation, either via your local account executive or via https://62368-ul-solutions.com/contact-ul.html.

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