This document is published as a dual logo standard and is applicable for the explosion protection requirements for the construction, testing and marking for Group I Ex Equipment that can be an individual item, or be an assembly of multiple items of Ex Equipment and Ex Components forming mining machinery. The standard atmospheric conditions (relating to the explosion characteristics of the atmosphere) under which it can be assumed that Ex Equipment can be operated are: - temperature −20 °C to +60 °C; - pressure 80 kPa (0,8 bar) to 110 kPa (1,1 bar); and - air with normal oxygen content, typically a volume fraction of 21 %. This part of ISO/IEC 80079 applies for Ex Equipment and Ex Components with Explosion Protection Levels (EPLs) Ma and Mb. This document supplements and modifies the general requirements of IEC 60079‑0. Where a requirement of this document conflicts with a requirement of IEC 60079-0, the requirement of this document takes precedence. This document can be used for guidance on underground applications where firedamp or coal dust can be present, but which are not Group I mines, for example tunnels. This second edition cancels and replaces the first edition, published in 2016. This edition constitutes a technical revision. Refer to the Foreword of the document for a complete listing of the technical changes between edition 2.0 and the previous edition of the document.