Preface: This is the fifth edition of CSA C22.2 No. 141, Emergency Lighting Equipment, one of a series of Standards issued by CSA Group under Part II of the Canadian Electrical Code. This edition supersedes the previous editions published in 2010, 2002, 1985, and 1972. For general information on the Standards of the Canadian Electrical Code, Part II, see the Preface of CAN/CSA-C22.2 No. 0, General requirements - Canadian Electrical Code, Part II. Scope: 1.1 This Standard applies to exit signs, unit equipment, emergency luminaires, and central power systems intended for connection to circuits with nominal voltages of 600 V and less and providing illumination in the event of a failure of the normal power supply for nonhazardous locations in accordance with the Rules of the Canadian Electrical Code, Part I. 1.2 This Standard includes requirements for the construction of emergency lighting equipment to preclude fire and shock hazards and to ensure that the equipment has the minimum capability for performing its intended function. 1.3 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 (non-mandatory) to define their application. 1.4 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.