Update #1 was published as notification that this is now a National Standard of Canada.
Preface
This is the third edition of CSA C22.3 No. 7, Underground systems, one of a series of Standards issued under the Canadian Electrical Code, Part III. It supersedes the previous editions published in 1994 and 1986.
This edition includes criteria related to the following topics, which were not included previously in this Standard:
(a) mechanical protection of pad-mounted equipment;
(b) identification of interconnected supply equipment;
(c) excavation in unstable soil;
(d) overvoltage protection;
(e) inductive coordination;
(f) recognition of supply, communication, and gas joint trenching;
(g) cable pulling tension; and
(h) access to and egress from underground chambers.
CSA acknowledges the generous support of the Canadian Electricity Association (CEA) in the development of this Standard.
This Standard was prepared by the Technical Committee on Underground Construction, under the jurisdiction of the Strategic Steering Committee on Power Engineering and Electromagnetic Compatibility, and has been formally approved by the Technical Committee. It will be submitted to the Standards Council of Canada for approval as a National Standard of Canada.
Scope
1.1
This Standard applies to the lines and equipment associated with underground electric supply and communication systems located entirely outside buildings and fenced supply stations. See CSA C61936-1 for installations within fenced or indoor supply stations.
1.2
This Standard, which forms part of the Canadian Electrical Code, Part III, covers the requirements for the construction of underground systems and includes electric supply and communication circuits that are installed alone, in joint use, or in proximity to each other or other facilities, and that
(a) cross each other or other facilities;
(b) cross under railways or highways; or
(c) run under ground that is likely to be traversed by vehicles or pedestrians.
1.3
The requirements of this Standard do not constitute complete construction specifications but stipulate the minimum design requirements with regard to
(a) safety of persons;
(b) continuity of service; and
(c) protection of property.
1.4
The selection, design, and installation of transmission cables are not addressed in this Standard. Underground electrical supply transmission installations are custom designed by engineering specialists according to local conditions and the requirements of the owner or operator of the transmission system.
1.5
Conditions not covered by this Standard are governed by equivalent Standards in common use or by the authority having jurisdiction.
1.6
In some cases, requirements are written for specific types of construction. This does not preclude the use of other types of construction arising out of continuing advancements in the field, provided that engineering representatives can demonstrate the safety and suitability of these alternatives.
1.7
The use of terms such as where practical is not intended to provide an opportunity for not meeting the minimum requirements of this Standard. Where an alternative is not specified, the engineering solution that most closely adheres to the preferred method is to be used. Where the requirements of more than one clause apply, all are to be satisfied.
1.8
In CSA Standards, 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; may is used to express an option or that which is permissible within the limits of the standard; and can is used to express possibility or capability. 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.
