SNZ AS/NZS 7000
Overhead line design
|Publication Date:||17 May 2016|
SCOPE AND GENERAL
This Standard specifies the general requirements that are to be met for the design and construction of new overhead lines to ensure that the line is suitable for its intended purpose, and provides acceptable levels of safety for construction, maintenance and operation, and meets requirements for environmental considerations.
This Standard is only applicable to new overhead lines and is not intended to be retrospectively applied to the routine maintenance, and ongoing life extension of existing overhead lines constructed prior to the issue of this Standard. Such maintenance and life extension work ensures that lines continue to comply with the original design standards and remain safe and 'fit for purpose'.
Where the additional loading does not exceed the foundation or major structural element capacities, it is not necessary to comply with this Standard. Modifications may be made to comply with the Standard applicable to the original design. Major structural elements include poles, lattice tower legs and foundations.
However, where existing overhead lines are proposed to be altered such that elements of the overhead line may be overloaded or overstressed to the original design standard; then the overhead line is required to be assessed by a competent person for compliance with the provisions of this Standard.
This Standard is applicable to overhead lines supporting telecommunication systems or where they are used on overhead lines either attached to the aerial line conductor/earth wire systems or as separate cables supported by the supports. These telecommunication systems include optical ground wires (OPGWs), optical conductors and all dielectric self supporting (ADSS) cables.
It is also applicable to overhead line structures supporting telecommunications equipment.
The electrical requirements of this standard apply to alternating current (a.c.) systems with a nominal frequency of 50 Hz.
This Standard does not apply to catenary systems of electrified railways.
NOTE: Overhead line design handbook HB 331 complements this Standard providing further information and worked examples.