This article covers some changes in the rules for installing wiring and cables provided in the new 2002 edition of the Canadian Electrical Code.
In earlier versions of the code, Rule 4-004(1)(d) and (2)(d) allowed the use of IEEE Standard, Power Cable Ampacity Tables IEEE 835 with the alternative of using the Appendix D underground ampacity tables to size underground cables. Although not stated in the rule, the IEEE tables could provide reduced wire sizes for load factors less than 1.00. Now Rules 4-004(15) and (16) have been added to further explain the use of the IEEE 835 tables, by including their use for loads having load factors less than 1.00 with supporting documentation. Appendix B still specifies the types of data that must be submitted to justify every request for using this of method to arrive at reduced cable ampacities. Nothing much has changed, except that use of the IEEE tables is clarified.
Beware, the Appendix D ampacity tables for underground conductors have been reshuffled, and some now have different table numbers. These tables and their accompanying diagrams are still to be found in separate appendices, the tables in Appendix D and the diagrams in Appendix B. Wouldn’t it have been great if everything could have been brought together in one place, so we wouldn’t have to turn so many pages? There is also a new footnote 4 under the tables which, when interpreted, means that the ampacity values of each table have been re-adjusted to satisfy continuous loading requirements where necessary.
Table 19 is where to find the approved installation methods and uses for electrical wire and cables. Table 19 now also includes optical fiber cables.
A new Rule 12-942 specifies that metal raceways in parking lot slabs, pavements and roads must be corrosion-resistant or made corrosion-resistant. No doubt, this requirement was added to deal with the problems of road salt and its harmful effect on metals. It would probably be best to consult with your local electrical inspector for an exact interpretation of this new rule.
In previous editions of the code, Rule 12-1502 permitted the use of electrical nonmetallic tubing encased in concrete or direct buried. When not in concrete or underground, electrical nonmetallic tubing required mechanical protection, was restricted from use in hazardous locations, in thermal insulation and run where exposed. The new version of Rules 12-1500 and 12-1502 still specifies its use in masonry and concrete, but permits electrical nonmetallic tubing to be run exposed where not subjected to damage when it has a suitable flame spread rating. The hazardous location restriction has been removed, since this is well covered in Section 18, Hazardous Locations. The thermal insulation restriction is removed, but its maximum temperature is restricted to 75° C maximum. It must also be “approved for the purpose” when direct buried and include mechanical protection where there is risk of damage.
Previously, Rule 12-2202(2) and Table 42, Maximum Design Loads for Cable Trays, specified the maximum spacing for cable tray supports for different classes of cable trays. Table 42 is now deleted and the renumbered Rule 12-2200(2) asks us to rely upon the cable trays’ manufacturers’ data for the maximum spacing between cable tray supports.
Since we were old enough to shave, we have always known at least one absolute truth. It was not permitted to use electrical equipment neither as a splitter nor as a raceway between equipment. How the world has changed! Rule 12-3034(2)(a) now permits a tap from either the incoming or outgoing double lugs of electrical equipment to supply other equipment as long as no more that 75 percent of its wiring space is filled up. Rule 12-3034(2)(b) also permits an electrical equipment enclosure to be used as a raceway for wiring passing through to other equipment as long as no more than 40 percent of its wiring space is filled. What next, wooden fuses?
Earlier Subrules 6-300(3) and (4) specified that underground service conduit entering a building must be drained and sealed to prevent the entrance of moisture and gases. A new requirement, service conduit must also enter buildings above grade where practicable. Here’s another case where an electrical inspector’s interpretation might be helpful.
In the past, Rule 32-202 restricted the wiring methods for fire pumps to metal raceways, armoured cables and metallic sheathed cables. Now rigid nonmetallic conduit and electrical nonmetallic tubing encased in minimum 50 mm of concrete or masonry are added to the list of acceptable methods for connecting fire pumps.
As in the case of previous articles, you should always check with the electrical inspection authority for a more precise interpretation of any of the above in each province or territory as applicable.