Preface This is the second edition of CSA C22.2 No. 204, Line isolation monitors. It is one of a series of Standards issued by CSA Group under Part II of the Canadian Electrical Code. It supersedes the previous edition published in 1984. The changes to this edition include a) adding the requirement to comply with CAN/CSA-C22.2 No. 0; b) increasing the limit for maximum total hazardous index from 2 mA to 5 mA; c) reducing in the tolerance for the rms value of the monitor hazard index; d) clarifying the visual indicator; e) replacing clauses that are now covered by other CSA Group standards with references to those standards; and f) updating the referenced standards listed in Clause 2. Scope 1.1 This Standard applies to line isolation monitors designed to be installed and used as an ancillary part of a single-phase isolated (ungrounded) power distribution system not exceeding 300 V in accordance with the rules of the Canadian Electrical Code, Part I, including any rules that are applicable particularly to anaesthetizing locations and other patient care areas in hospitals and other health care facilities. 1.2 This Standard applies to all line isolation monitors and includes requirements for the enclosure in which they are mounted for installation. 1.3 This Standard applies to monitors of a kind that are programmed to measure, periodically or continuously, an impedance to ground of each "side" of a single-phase power supply and any connected load and to activate an alarm whenever either or both of these impedances are equal to or less than a preset limit. 1.4 This Standard applies to remote indicators designed to duplicate some or all of the alarm indications that are presented by a line isolation monitor. 1.5 This Standard does not include requirements for monitors for installations in hazardous locations, as Canadian Electrical Code, Part I does not provide for their installation in such locations. 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 (non-mandatory) to define their application.