Sch 1Requirements for aerial lines

Schedule 1—Requirements for aerial lines (regulation 48) listed standards means the standards (both national and international), codes, guides and other documents, as published from time to time, listed in the Appendix at the end of this Schedule; maximum design temperature means the maximum temperature that conductors may reach under the influence of load current (excluding fault current), ambient temperature of the air and solar radiation. 2—Design Aerial lines must be designed so that the lines— (a) have safe levels of electrical insulation; and (b) will carry the electrical load currents for which they are designed without failure; and (c) will allow the passage of electrical short circuit currents which will enable the correct operation of protective devices; and (d) are structurally secure for the environmental and service conditions for which they are designed; and (e) maintain safe clearances, 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. 3—Materials Aerial line structures, their components, conductors, cables and 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—Thermal ratings (1) The thermal capacity of a conductor must be sufficient to pass the electrical load for which it is designed without losing any mechanical properties that would affect the safety of the line. (2) Thermal ratings of conductors must be determined in accordance with the guidelines set out in the listed standards. 5—Short circuit ratings (1) The conductors of aerial lines must be of sufficient size to pass short circuit currents so as to enable the correct operation of protective devices without losing any mechanical properties that would affect the safety of the line. (2) Short circuit capacity of conductors must be determined in accordance with the guidelines set out in the listed standards. 6—Mechanical loading conditions (1) The mechanical loads used for the design of aerial lines must be based on the local environment and electrical service conditions. (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) Mechanical loading conditions must be determined in accordance with the guidelines set out in the listed standards. 7—Conductor tensions (1) The conductors for use with aerial lines must be designed to withstand the mechanical loads determined for their operation over the designed operational life of the line. (2) Conductors for lines must be designed 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. 8—Structures and footings (1) The structures and footings for use with aerial lines must be designed to withstand the mechanical loads determined for their operation over the designed operational life of the line. (2) Structures and footings for lines must be designed 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. 9—Facade mounted cables (1) Cables and accessories designed for facade mounting must be constructed with suitable insulated conductors and be manufactured to be durable for the environment and service conditions for which they are designed. (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) Mechanical loading conditions must be determined in accordance with the guidelines set out in the listed standards. 10—Safety clearances (1) Aerial lines must be designed to maintain safety clearances to the ground and other buildings or structures under the environmental and electrical service conditions determined for the line. (2) In determining circuit arrangement, 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) The environmental and electrical conditions for the determination of clearances to lines must be determined in accordance with the listed standards. (4) Aerial lines must be designed so that safety clearances are as follows: (a) for an aerial line (other than a facade mounted line) constructed to operate at a voltage of 66 kV or less—so that the vertical or horizontal distance from any building or structure (other than a support to which the aerial line is attached or a support of another overhead line which crosses the aerial line) to any position to which a conductor in the aerial line may sag at maximum design temperature, or move as a result of normal prevailing wind pressures, is not less than the relevant distance as set out in Table 1; The figures following Table 1 are to be used to assist in understanding the information contained in the Table. (b) for an aerial line (other than a facade mounted line) constructed to operate at a voltage of more than 66 kV—so that the horizontal distance from any building or structure (other than a support to which the aerial line is attached or a support of another overhead line which crosses the aerial line) to the centre‑line of the aerial line is not less than the relevant distance as set out in Table 1; The figures following Table 1 are to be used to assist in understanding the information contained in the Table. (c) for an aerial line (other than a service line, other cable system or aerial line within a substation)—so that the distance to the ground in any direction from a position to which any part of the aerial line may sag at maximum design temperature, or move as a result of normal prevailing wind pressures, is not less than the relevant distance as set out in Table 2; (d) for a service line or other cable system—so that the distance to the ground in any direction from a position to which any part of the service line or cable system may sag at maximum design temperature, or move as a result of normal prevailing wind pressures, is not less than the relevant distance as set out in Table 3; (e) for a facade mounted line— (i) so that the distance from any part of the facade of the building which supports a line to any position to which the line may sag at maximum design temperature is not less than the relevant distance set out in Table 4; (ii) where it is designed so the line is more than 0.3 m from the facade of the building supporting it—so that the requirements of paragraphs (a) and (d) are complied with. (5) The arrangement of and clearances between circuits, either attached to a common structure, unattached, in shared spans or crossing, must be designed to be safe for the environmental and electrical service conditions for which they are designed 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. (6) Aerial lines operating at a voltage greater than 66 kV must not be installed above any building or structure. 11—Installation of aerial lines Aerial lines must be installed in accordance with the guidelines set out in the listed standards. 12—Maintenance of aerial lines (1) Aerial lines, their structures and components must be maintained to be in a safe operating condition. (2) A system of maintenance must be instituted for aerial lines, their structures and their components, including— (a) predetermined processes to confirm the safe state of components; 13—Tables