10-700 Grounding electrodes (see Appendix B)
(1) Grounding electrodes shall consist of
(a) manufactured grounding electrodes;
(b) field-assembled grounding electrodes installed in accordance with this Rule; or
(c) in-situ grounding electrodes forming part of existing infrastructure as defined in this Rule.
(2) Manufactured grounding electrodes shall
(a) in the case of a rod grounding electrode, consist of 2 rod electrodes (except for a chemically charged rod electrode where only one need be installed) spaced no less than 3 m apart,
(i) bonded together with a grounding conductor sized in accordance with Table 17; and
(ii) driven to the full length of the rod; or
(b) in the case of a plate electrode, be
(i) in direct contact with exterior soil at no less than 600 mm below grade level; or
(ii) encased within the bottom 50 mm of a concrete foundation footing in direct contact with the earth at not less than 600 mm below finished grade
appendix B
D
Rules 10-700(1)(a), 10-700(4)
Manufactured grounding electrodes are those manufactured and certified to CSA C22.2 No. 41.
It is important that in-situ grounding electrodes provide an equivalent surface area contact with earth as do manufactured electrodes (see CSA C22.2 No. 41). Consideration should also be given to the effects that corrosion may have on the in-situ ground electrode impacting durability and life-expectancy. For example, an underground metal water piping system located at least 600 mm below finished grade and extending at least 3 m has traditionally been recognized as a suitable grounding electrode. Similarly, the metallic reinforcement of a concrete slab, concrete piling, or concrete foundation and iron pilings in significant contact with earth at 600 mm or more below finished grade have also been found to be suitable in-situ electrodes.
Any metallic material encapsulated with a non-conductive compound to protect it from corrosion would not meet the criteria for use as in-situ ground electrode.
