The UL 508A 3rd Edition, published in April 2018 and effective as of July 1, 2020
Interlocking: Revised requirements for industrial machinery panels now allow disconnect interlocking means to prevent power restoration while a door is open unless a defeat mechanism is used. Critical Design & Compliance Factors Ul 508a 3rd Edition Pdf
The 3rd Edition mandates clear separation between panels rated for high-fault (≥5 kA) and low-fault (<5 kA) applications. The method for determining SCCR now requires a "series combination" approach using tested component combinations. The UL 508A 3rd Edition, published in April
UL 508A Third Edition Summary of Requirements - UL Solutions The UL 508A 3rd Edition