The IEC webstore offers a (first few pages) for free – useful to verify the correct part number.

: The primary source for IEC 60099-5:2018 .

The International Electrotechnical Commission (IEC) sells its standards to fund ongoing development. Providing direct, free PDF links to copyrighted standards is illegal and violates IEC’s intellectual property rights.

The industry standard for system safety, detailed under IEC 60099-4.

: Provides recommendations for substation designers, utility engineers, and asset managers to optimize system reliability and safety. ANSI Webstore or find information on specific surge arrester types IEC 60099-5 - iTeh Standards

Always place arresters as close as possible to the protected apparatus to minimize "lead length" effects.

The standard covers aspects like:

The 2018 version (Edition 3.0) represents a significant technical revision over the 2013 edition. Major highlights include: IEC 60099-5:2018

Since IEC standards are copyrighted, official full versions are typically paid documents. You can find them at the following authoritative repositories:

IEC 60099-5 standard, titled "Surge arresters – Part 5: Selection and application recommendations,"