Bite the bullet and buy the official PDF from UL, or subscribe to a standards library (like IHS) if you need multiple UL standards. For the casual user, use the free "UL 508A Fact Sheet" instead of searching for the full PDF.
Using an official, up-to-date copy is vital because UL frequently issues "revisions" between major editions. Digital subscriptions through the UL "Digital View" platform often provide the most current information, including all recent bulletins and interpretations. Conclusion ul 508a 2022 pdf