Preface
This edition of CSA Standard C68.2; Concentric Neutral Power Cable, supersedes the first edition published in 1973.
This edition includes the following:
(a) Primary underground residential distribution cables (URD) and concentric neutral underground distribution cables (UD);
(b) Extension of the voltage range to 46 kV where the concentric neutral is grounded;
(c) Change in the partial discharge extinction level test;
(d) Deletion of 3/0 and 4/0 solid conductors;
(e) Change in the brittleness temperature for extruded shield insulation;
(f) Deletion of the 50 per cent minimum coverage requirement for the concentric neutral conductor.
Scope
1.1
This Standard applies to two-conductor electrical distribution cables consisting of one thermosetting insulated central conductor and one copper concentric conductor applied helically over the insulating shield with or without an overall jacket.
The cables are intended for underground installation and are of the following two basic types, designated as URD and UD respectively:
(a) Underground Residential Distribution Cables (URD). These cables are designed for use on single phase circuits commonly used in underground residential distribution systems; and
(b) Underground Distribution Cables (UD). These cables are designed for use on three phase circuits commonly used as feeder circuits or in urban, industrial, or three phase distribution systems. UD cables comprising a three phase circuit are commonly installed in the same trench or duct bank and may be of triplexed construction.
1.2
This Standard applies only to power cables 5 kV to 46 kV where the concentric neutral conductor is grounded (see Appendix A).
1.3
The insulation thicknesses as covered in this Standard are based on the 100 per cent insulation level grounded neutral system (see Appendix A).
