Preface This is the second edition of CSA C22.2 No. 269.4, Surge protective devices - Type 4 - Component assemblies. It supersedes the previous edition published in 2014. This Standard is one in a series of standards dealing with surge protective devices. This Standard is issued by CSA Group under Part II of the Canadian Electrical Code.? For general information on the Standards of the Canadian Electrical Code, Part II, see the Preface of CAN/CSA-C22.2 No. 0.? This edition incorporates numerous changes throughout to align the requirements with the revisions and updates made to other standards in this series.? Scope 1.1 This Standard covers component assembly surge protective devices (SPDs) consisting of two or more Type 5 components, intended for use in Type 1, 2, or 3 SPD applications or installation in other electrical equipment.? Note: SPD components containing integral thermal devices are within the scope of CSA C22.2 No. 269.5.? 1.2 Type 4 component assemblies are designed for repeated limiting of transient voltage surges as specified in this Standard on 50 or 60 Hz power circuits over 42 V and not exceeding 750 V.? 1.3 The surge protective component used in a Type 4 component assembly may include but not be limited to metal oxide varistors (MOVs), silicon avalanche diodes (SADs), spark gaps, and gas discharge tubes (GDT).? 1.4 This Standard does not apply to EMI filters which may have surge suppression characteristics as covered in CSA C22.2 No. 8.? 1.5 The values given in SI units are the units of record for the purposes of this Standard. The values given in parentheses are for information and comparison only.? 1.6 In this Standard, \"shall\" is used to express a requirement, i.e., a provision that the user is obliged to satisfy in order to comply with the standard; \"should\" is used to express a recommendation or that which is advised but not required; and \"may\" is used to express an option or that which is permissible within the limits of the standard.? Notes accompanying clauses do not include requirements or alternative requirements; the purpose of a note accompanying a clause is to separate from the text explanatory or informative material.? Notes to tables and figures are considered part of the table or figure and may be written as requirements.? Annexes are designated normative (mandatory) or informative (nonmandatory) to define their application.