The new 19th edition of the Canadian Electrical Code has brought about some changes in the grounding and bonding rules. Not many of these are major changes. In a few instances, a change might simply be the re-arrangement of some words or the relocation of rules to more logical places in the code. In this article, we will review some of the revisions made in Sections 10, 60, and 68 as they affect grounding and bonding.
The first revision we encounter is Subrule 10-206(1) that specifies the location of grounding connections for an isolated system either “at the source of supply or at the supply side of the first switch.” The previous CEC edition required this connection to be either “at the transformer, or other source of supply, on the supply side of the first switch controlling the system.” The words source of supply reduce the number of words used and confirm the idea that isolated systems may be supplied from power sources other than transformers. As you will recall, an isolated system is “not conductively connected to the distribution system,” for example 120/208 volts transformed down from the 600-volt distribution system in a building.
Subrule 10-206(1)(b) also specifies that when we have two or more isolated systems in a building, they should have a common grounding conductor, or if there are separate ground electrodes, they must be interconnected with minimum No. 6 AWG copper wire. The previous rule simply required that separate ground electrodes must be interconnected.
A small error has been corrected in Subrule 10-400(b), that earlier referred to “wiring containing a grounding conductor” as the means of bonding fixed equipment to ground. This has now been corrected by changing the term “grounding conductor” to “bonding conductor.”
Previous Subrules 10-510(1)(a) and (4), and 10-804(e), when referring to mineral-insulated cable sheaths used for bonding purposes, specifically prohibited the use of stainless steel. The present rule now specifies that mineral-insulated cable sheaths are unacceptable as bonding means “when not of copper or aluminum.” This twist means that stainless steel continues to be prohibited, but the rule now expresses the same requirement differently, in a way that emphasizes which types of sheaths are acceptable rather that what is prohibited.
Earlier editions of the Canadian Electrical Code contained references to wiring practices that were and continue to be unacceptable in a hazardous location. These rules have been removed throughout the code and either consolidated in Section 18, Hazardous Locations, or they may have already existed in that section of the code. One such rule was Rule 10-614, which specified that the bonding for hazardous location electrical equipment must be continuous from the hazardous location equipment to its source of supply outside the hazardous location, using the special bonding methods for the supply side of electrical service equipment. This rule is deleted, and the requirement covered in Section 18.
There are also a few changes in Section 68, Pools, Tubs, and Spas. A major change, Subrule 68-058(3) has been added to require that when the pool concrete reinforcing steel has a non-conductive coating, it cannot be relied upon when interconnected to serve as the means to eliminate voltage gradients across a pool. This brand-new requirement specifies that an alternate means of controlling voltage gradients must be used. Appendix B explains that as an alternative, a loop of copper wire, minimum size No. 6 AWG may be looped around the pool below the pool’s water line.
Subrule 68-068(7)(a) also has a small change. The previous rule specified that “receptacles and appliances” in swimming pool locker or change rooms had to be on a GFCI-protected circuit. The new rule only refers to “receptacles.” Presumably, this would exempt electric hand dryers and similar appliances from this requirement. This rule also refers to Appendix B, which explains the reason for the minimum 1.5 m distance between hydromassage tubs and ground-fault circuit interrupters (GFCIs), as necessary to prevent a person from resetting the GFCI while in the tub.
There is also a new Appendix B note for Section 60, Electrical Communication Systems, Rule 60-206 that refers to communications equipment in high voltage substations. This note explains why special precautions and equipment are necessary to prevent harm to equipment and people in the event of a substation ground fault and subsequent ground potential rise. IEEE Standard 487 is shown as the reference for providing this type of protection.
As with previous articles, you should check with the electrical inspection authority in each province or territory as applicable for a more precise interpretation of any of the above.