Standardization bodies like Underwriters Laboratories (UL) typically charge for their published standards to fund the research, testing, and maintenance required to keep them updated. Therefore, downloading a full, printable, and official UL 508A PDF for free from a legal source is generally not an option.

You're looking for a free PDF of the UL 508A standard. UL 508A is a safety standard for industrial control panels, and it's published by Underwriters Laboratories (UL).

Please note that while you may find some websites offering free PDFs of UL standards, these may be unofficial or outdated versions, and it's recommended to purchase the official standard from UL or another authorized distributor to ensure you have the most up-to-date and accurate information.