Glossary and definitions

Arboricultural professional

a person with an appropriate qualification and experience in the trimming, removal and management of trees and vegetation.

Base footprint

the ground area on which an existing tower stands, the dimensions of which are defined by the outer points of the structure at ground level (not including concrete foundations).

Building or structure

a building or structure large enough to pose a risk to transmission. A firm definition needs to be developed for inclusion in NES regulations.

Circuit

a set of conductors (normally three) plus associated hardware and insulation on a transmission line, which together form a single electrical connection between two or more stations.

Conductor

the wire that carries electricity along a transmission line, and is made of copper or steel-reinforced aluminium. Simplex, duplex, triplex, quadplex refer to conductors of the same phase in a single, double, triple or quadruple configuration, respectively.

Dry abrasive blasting

the use of an abrasive material which is entrained in air and blasted at pressure onto a structure to abrade / remove surface layers of paint, zinc galvanising and rust.

Earthworks

the disturbance of the land surfaces by methods including blading, contouring, ripping, moving, removing, placing, replacing, excavating, cutting and filling.

Enhancement or upgrading

all activities and effects relating to an increase in the carrying capacity, efficiency or security of transmission lines; for example:

b. alteration of, and extensions to, towers and poles, including works required in order to achieve compliance with the New Zealand Electrical Code of Practice for Electrical Safe Distances (NZECP 34: 2001) (eg, re-tensioning and re-sagging of conductors)

c. addition of circuits to lines

d. alterations to insulators and other hardware

e. erection of temporary structures and lighting

f. addition of conductors and / or replacement of conductors with larger conductors

g. earthworks, and trimming of trees and vegetation, associated with enhancement activities

h. construction noise and vibration associated with enhancement activities

i. use of machinery and vehicles associated with enhancement activities

j. increasing the voltage or current-carrying capacity of a line, or both.

Earthworks

the disturbance of the land surface by blading, boring, contouring, drilling, ripping, moving, removing, placing or replacing soil or earth; or by excavation, or by cutting or filling operations.

Height

the height of a transmission line structure (including conductors and earth peaks on towers, but not lightning spikes on poles) above ground level (natural or modified).

Implosive jointing

the compression of a fitting on a conductor or earth wire by means of a compressive implosive force.

Line owner / operator

Transpower New Zealand Ltd, a state-owned enterprise, is the sole owner and operator of the high-voltage electricity transmission network (national grid).

Maintenance

all activities and effects associated with the repair and replacement of transmission lines; for example:

a. repair, replacement and reconfiguration of fixtures and fittings, including cross-arms and insulators

b. repair and replacement of conductors

c. re-tensioning and re-sagging of conductors

d. temporary line deviations

e. wet and dry abrasive blasting

f. non-abrasive washing of towers

g. painting of towers and poles

h. repair, strengthening, and replacement of towers, poles and support structures, including foundation works

i. carrying out earthworks

j. trimming and removal of trees and vegetation

k. erection of temporary structures and lighting

l. maintenance of access tracks, including trimming or removal of vegetation and any earthworks

m. use of machinery and vehicles associated with maintenance activities

n. construction noise and vibration associated with maintenance activities.

National grid

the high-voltage electricity transmission network owned and operated by Transpower New Zealand Ltd. The technical definition of the national grid contained in the Electricity Governance Rules (Electricity Commission, 2007) is: “the system of transmission lines, substations and other works, including the High Voltage Direct Current link, used to connect grid injection points and grid exit points to convey electricity throughout the North and South Island of New Zealand”.

Nip-tuck

Reducing conductor sag (and increasing the tension) across one or more spans by removing a length of conductor from one span (nip) which tightens the conductor in that span and in adjacent spans (tuck).

Non-abrasive washing

washing or water blasting involving the use of water at pressure (approximately 5,000 psi water blast stream), where no treatment chemicals or additives have been added to the water being used.

NZECP 34

the New Zealand Electrical Code of Practice for Electrical Safe Distances, reference NZECP 34: 2001 (Ministry of Consumer Affairs, 2001).

Occupied building

a building, as under the Building Act 2004, that is used for habitation or regular occupation, including dwelling houses, schools, hospitals and visitor accommodation.

Operation

all activities and effects associated with the use of transmission lines to convey electricity; for example:

a. inspection

b. the generation of noise

c. switching circuits on and off, and de-energising circuits

d. the livening of existing circuits not currently used to convey electricity

e. the placement of signs and hazard markers on towers, poles and conductors

f. telecommunications

g. use of access tracks by machinery and vehicles

h. currents varying in the line, depending on time of day, load etc.

Overhead line support

a pole or tower (pylon) used to support electrical conductors (wires).

Pole

a transmission line support structure, comprising up to three vertical supports, as well as its cross-arms, components and guy wires (in addition to the vertical supports).

Removal

in relation to trees and other vegetation, means the relocation, spraying or other activity that results in the permanent destruction of the tree or other vegetation.

Scheduled heritage item

an item, including a site, area or precinct, that has been explicitly scheduled in a district plan for protection of its historic heritage or cultural values.

Scheduled landscape / ecological protection areas

those areas explicitly scheduled or listed in district plans that seek to protect nationally outstanding landscapes and natural features (section 6(b) RMA), areas of significant indigenous vegetation and significant habitats of indigenous fauna (section 6(c) RMA), and also including mapped significant ridgelines and public view shafts. This excludes landscape or ecological management overlays, character or policy areas.

Scheduled transmission heritage item

a transmission line or parts thereof explicitly scheduled in a district plan for protection for its historic heritage values.

Scheduled tree / vegetation

individual trees or areas of vegetation explicitly identified and scheduled in a district plan for the purposes of protection and management.

Suitably qualified electrical engineer

A Qualified Electrical Engineer licensed by the Electricity Workers Registration Board or recognised under the Electricity Act 1992.

Telecommunications

has the same meaning under the Telecommunications Act 2001, but is limited to telecommunication facilities used as part of the operation of the transmission network.

Temporary line deviation

the construction and use of a non-permanent section of transmission line to divert electricity transmission during the repair, maintenance or enhancement of an existing section of transmission line; the temporary line is taken down once the repair, maintenance or enhancement is completed.

Temporary structure

a non-permanent structure (whether or not a building consent is required) required for a specific maintenance or enhancement task, which is removed once the task is completed.

Tower

a lattice-steel transmission line support structure, including all necessary cross-arms and components.

Tower relocation envelope

see diagrams below.

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Figure 7: Tower relocation envelope for controlled activities

 

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Transmission activities

all activities associated with the operation, maintenance and upgrading of transmission lines.

Transmission line

all facilities and structures used or associated with the high-voltage transmission of electricity within the national grid, excluding substations.

Trimming

in relation to trees and other vegetation, includes pruning, limbing-up, or other changes that could affect the health and form of the tree or vegetation.

Upgrading

see Enhancement.

Wet abrasive blasting

the use of an abrasive material which is entrained in water and blasted at pressure onto a structure to abrade surfaces.