Go to shop.ul.com and search for "UL 508A".
UL 508A is the nationally recognized standard in the U.S. and Canada (via CSA) for the construction, component selection, and marking of industrial control panels. Compliance is required for NRTL (Nationally Recognized Testing Laboratory) certification, typically by UL, ETL, or CSA. ul 508a download pdf
Does not apply to: household appliances, office equipment, or panels for hazardous locations (see UL 698A). Go to shop
| Feature | UL 508A | IEC 61439 | |---------|---------|-----------| | SCCR determination | Supplement SB calculation | Short-circuit withstand test | | Component focus | Listed/recognized devices | Assembly verification | | Typical voltage | ≤600V | ≤1000V | If you already have an older hard copy
While the full book usually requires a purchase, UL often releases and Summary of Changes for free on their website. If you already have an older hard copy of the standard, downloading these free PDF supplements can keep you current without buying a whole new book.
It is a common misconception that you can legally download the full, current version of UL 508A for free on random file-sharing sites. UL standards are copyrighted documents, and downloading them from unauthorized sources can be risky (malware) and is technically a violation of copyright.