ELECTRICITY (GENERAL) REGULATIONS 2012 - SCHEDULE 2

ELECTRICITY (GENERAL) REGULATIONS 2012 - SCHEDULE 2

Schedule 2—Requirements for underground lines and certain other powerlines

(regulations 49 and 50)

1—Interpretation

In this Schedule—

listed standards means the standards (both national and international), codes, guides and other documents listed in the Appendix at the end of this Schedule as published as referred to in the Appendix or, if no such reference is included in the Appendix, as published from time to time.

2—Design—general

        (1)         Underground lines must be designed so that—

            (a)         cables have safe levels of electrical insulation; and

            (b)         cables will carry load currents for which they are designed without failure; and

            (c)         cables will pass short circuit current which will enable the correct operation of protective devices; and

            (d)         the required clearances between a building or structure and an underground powerline as prescribed by regulation 82 are maintained,

and so as to comply with the listed standards or achieve, to the satisfaction of the Technical Regulator, the same or better safety and technical outcomes.

        (2)         In determining electrical service conditions and the physical environment under which the line will operate, due care must be given to the consideration of extremes that may occur, the likelihood of their occurrence and the associated risks.

3—Cables and accessories

Cables and their accessories must, so as to ensure safe operational performance, conform to the listed standards or achieve, to the satisfaction of the Technical Regulator, the same or better safety and technical outcomes.

4—Cable ratings

        (1)         The rating of a cable must be sufficient to pass the electrical load for which it is designed without failure or excessive heating.

        (2)         Rating of cables must be determined in accordance with the listed standards.

5—Short circuit rating of conductors and cable screens

        (1)         The cable conductors and cable screens must be of sufficient size to pass short circuit currents without overheating for the time taken for the operation of the protective device.

        (2)         The short circuit capacity of cable must be determined in accordance with the listed standards.

6—Installation—general

Underground lines must be installed in a safe manner in accordance with this Schedule and the listed standards or so as to achieve, to the satisfaction of the Technical Regulator, the same or better safety and technical outcomes.

7—Installation of underground lines

        (1)         An underground line must be installed in accordance with Table 1 below and, subject to this clause, at the depth fixed for the designated voltage and cable type.

        (2)         For the mechanical cover and enclosures referred to in Table 1 below, 1 of the following must be used:

            (a)         a layer of concrete at least 50 mm thick with a characteristic strength defined by AS 3600 and AS 1012 and determined to be not less than 15 MPa at 28 days placed not less than 50 mm and not more than 150 mm above the cable and overlapping the cable by at least 40 mm on each side; or

            (b)         concrete slabs of at least 40 mm thickness with a characteristic strength defined as AS 3600 and AS 1012 and determined to be not less than 15 MPa at 28 days with—

                  (i)         each slab touching the next so that there are no spaces left between slabs; and

                  (ii)         the slabs being placed not less than 50 mm and not more than 150 mm above the cable and overlapping the cable by at least 40 mm on each side of the cable; or

            (c)         a plastic or composite material that offers comparable protection (depending on depth of installation).

        (3)         The enclosure referred to in the last column of Table 1 must be a medium or heavy galvanised steel tube conforming to AS 1074 or a non-metallic heavy duty conduit conforming to AS/NZS 2053 (depending on depth of installation).

        (4)         If it is impractical to lay an underground line at a depth which complies with Table 1 then they may be laid at a lesser depth provided that additional covers or enclosures are installed to provide equivalent protection to that prescribed.

        (5)         The underground line, from where it enters the ground to a position where it complies with the requirements of depth and protection in Table 1, must be protected by a cover or enclosure described above.

        (6)         Table

TABLE 1: Minimum depth of burial from surface of ground to top of cable or enclosure

8—Part of underground line installed on or above ground

        (1)         If an underground line is located on the surface of the ground or attached above the surface of the ground, it must be mechanically protected to a height of 2.4 m from any surface on which a person can stand to the point where it enters the ground.

        (2)         The mechanical protection must be provided—

            (a)         by a cable guard made of mild steel of 2.5 mm thickness for HV cables and 1.6 mm thickness for LV cables, galvanised to AS/NZS 4680, AS/NZS 4791 or AS/NZS 4792; or

            (b)         a galvanised steel tube conforming to AS 1074; or

            (c)         some other material giving equivalent mechanical protection.

        (3)         If the attachment of the underground line is more than 2.4 m from a surface on which a person can stand, the cable need not be mechanically protected provided that—

            (a)         the cable is beyond reach (determined in accordance with AS 2067 Appendix G) from windows or other accessible parts of the building; or

            (b)         the cable is less than or equal to 1 000 volts; or

            (c)         the cable is more than 1 000 volts but is metallic screened; or

            (d)         the cable is within a substation.

        (4)         If the cable is high voltage, it must be enclosed in metallic piping or casing which is earthed in accordance with these regulations.

9—Shared trenches

Separation between cables and service lines of other utilities laid parallel must comply with the listed standards.

10—Maintenance

        (1)         Underground lines must be maintained to be in a safe operating condition.

        (2)         A system of maintenance must be instituted for underground lines and their components, including—

            (a)         predetermined processes to confirm the safe state of components;

            (b)         managed replacement programs for components approaching the end of their serviceable life.

        (3)         Maintenance programs must be carried out in accordance with the listed standards.

Appendix—Standards, codes, guides and other documents relating to underground lines