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How the National Environmental Standards deal with electricity transmission activities (6 of 12)

These pages set out aspects of the NES that Transpower and councils need to consider for transmission activities.

  1. Summary of the NES
  2. Operation of existing transmission line and use of access tracks
  3. Overhead conductors and adding overhead circuits
  4. Earthwires and telecommunications cables
  5. Work on underground conductors / Taking existing overhead transmission lines underground
  6. Increasing voltage or current rating / Electric and magnetic fields
  7. Transmission line support structures — alteration, relocation, and replacement / Temporary / Removal
  8. Telecommunications and signs / Devices / Signs
  9. Discharges
  10. Trimming, felling, and removing trees and vegetation
  11. Earthworks
  12. Noise and vibration from construction activity

Increasing voltage or current rating

If the voltage or current rating of a transmission line is increased, the conditions for electric and magnetic fields (EMF) must be complied with - regulation 10.  Transpower will need to model the maximum EMF from the increased voltage or current rating to confirm that the limits on exposure s to EMF will be complied with.  The modelling results can be requested by the territorial authority, who deals with EMF as an effect of the land use.

The EMF conditions also apply if the configuration of a line is changed significantly, for example putting an overhead line underground (see above), or permanently moving support structures a considerable distance from their baseline positions. If the conditions are not complied with, the activity will be non-complying - regulation 13.

Electric and magnetic fields

Explanation: EMF conditions

Increasing the current or voltage of transmission lines is a permitted activity, provided that conditions relating to electric and magnetic fields are met - regulation 10.

Different limits, and different methods of modelling, apply to overhead and underground lines, and to alternating current and direct current lines.

For technical information on EMF see Electric and Magnetic Fields.

Explanation: breach of EMF conditions non-complying

If increasing the voltage or current rating of a line, or any of the other listed activities listed in regulation 13 result in the EMF conditions being breached, the activity is non-complying.

Other activities that become non-complying if the EMF conditions are not met are:

  • adding a conductor or circuit
  • undergrounding
  • altering, relocating, or replacing a transmission line support structure (other than as part of a temporary line deviation or undergrounding) if the structure is moved outside the allowable distance or height limits for controlled activities.

For technical information on EMF see Electric and Magnetic Fields.

Associated activities that may need consent

Increasing the voltage or current rating of transmission lines may require work on the conductors and support structures.  For example, conductors may need to be tightened to reduce sag, or tower height raised.

Increasing voltage and current capacity may also require ancillary work and result in associated effects, such as tracking to access the lines, earthworks to create platforms for equipment, noise generated from the use of machinery or vegetation clearance.  Work on conductors may be done in conjunction with tower maintenance (eg, cleaning, painting, maintaining tower foundations) and consents may also be required for some of these activities.

See Adding overhead circuits to determine if any other consents are needed for a project to add a circuit to these selected lines. See Transmission line support structures—alteration, relocation, and replacement to assess consent requirements for activities on transmission line support structures.

 

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Last updated: 18 January 2010