While direct PDF copies of the IEC 60099-4 standard are protected by copyright and usually require purchase, you can access technical overviews and previews from authorized distributors. What is IEC 60099-4?

The most recent significant update (Edition 3.0) introduced major shifts in how arresters are classified:

High Voltage Surge Arresters Buyer’s Guide - Hitachi Energy Publisher

A: No. Single-user PDFs are watermarked and tracked. Purchase a multi-user license.

from the preview. Then search for those standards individually (they may be available free from ISO or other bodies).

For those interested in learning more about IEC 60099-4, here are some key points:

The maximum permissible r.m.s. voltage at which the arrester is designed to operate. This is the foundational parameter for selecting an arrester.

or "sample" PDF that includes the Table of Contents, scope, and introductory sections. Third-Party Sharing Platforms: Sites like

Verifies the arrester's ability to withstand high-magnitude lightning currents (typically 65 kA or 100 kA).

To understand the importance of the standard, one must understand the device it governs. In the past, surge arresters utilized spark gaps and silicon carbide elements. Today, the industry standard is the metal-oxide varistor (MOV). These devices act as non-linear resistors. Under normal system voltage, they act as insulators. When a surge (such as lightning or a switching transient) occurs, they become conductors, clamping the voltage and diverting the energy to the ground, thereby protecting expensive transformers and switchgear.

While not recommended for new designs, (e.g., IEC 60099-4:2009) are no longer copyright-enforced in many jurisdictions. You can find these on: