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Appendix 5: Proposed NES: activities that could put transmission lines at risk

Objective

The objective of the transmission risks NES is to establish consistent and reasonable controls on activities that could adversely affect the transmission lines, or pose a risk to the person undertaking the activity.

Scope

The proposed standard would set controls on activities carried out in the immediate vicinity of transmission lines that could adversely affect the lines or affect public safety. The proposed standard would apply to anybody other than the line owner undertaking activities adjacent to transmission lines that are not related to transmission operation, maintenance and upgrade. Earthworks and structures adjacent to transmission lines required as part of line maintenance and enhancement and undertaken by the line owner are controlled by the proposed transmission activities NES.

How the proposals would work

Plans cannot be more lenient than the NES. However, the NES will state that plans can be more stringent. A rule in a plan which covers the same activity as the NES (eg, subdivisions) will be able to be more stringent than the NES, and the matters for consideration listed in the plan rule will apply. For example, a plan could specify that subdivision is a restricted discretionary activity, whereas the proposed NES specifies that subdivision near transmission lines is a controlled activity. Where an activity is not addressed in the NES, the district plan rules would continue to apply.

Table A8 shows the detailed proposals and their relationship between the proposals and existing NZECP 34 provisions or district plan rules. A key difference between RMA controls and NZECP 34 is that NZECP 34 gives the line owner the discretion to allow activities, whereas under the proposed NES the local authority would have the discretion to grant or decline resource consents.

The proposed controls are based on existing controls in the mandatory code of practice for electrical safe distances (NZECP 34) and existing provisions in district plans under the RMA. Controls on excavating and depositing materials and building boat ramps near transmission lines, and on buildings and structures near transmission support structures, are based on the electrical safe distances and matters set out in NZECP 34. In addition, controls are proposed for subdivision within 20 metres of transmission lines, based on section 11 of the RMA. These controls are based on the existing requirements in district plans.

Two options are presented for buildings and structures near conductors:

  • one based on NZECP 34
  • the other extending the radial electrical safe distances to a 20-metre ground-level zone within which resource consents would be required.

Option A (based on NZECP 34 safe distances)

  1. Buildings within the distances specified in schedule 3 pose electrical safety risks and are prohibited.
  2. Buildings outside the distances specified in Schedule 3 (as certified by a qualified electrical engineer) but within the distances specified in Schedule 2 require a resource consent.
    Anyone wanting to build within the distances from the conductors specified in Schedule 2 (see below) must demonstrate that the safe distances in Schedule 3 would not be exceeded. The Schedule 3 distances take account of the feasibility of lines coming into contact with buildings, and take particular account of accessibility to people and exposure to hazards.
  3. Buildings outside the safe distances specified in Schedule 2 are not regulated by the proposed NES. The distances set out in Schedule 2 (from NZECP 34) are vertical distances under conductors, and distances to the side of conductors. They contain a conservative margin of error to allow for possible line sag and swing, and vary according to span length (and a small amount of variation based on voltage). These are simple distances, so expert advice is not required.

Option B (based on 20-metre ‘consent required’ zone)

  1. Buildings within the distances specified in Schedule 3 pose electrical safety risks and are prohibited.
  2. Buildings within 20 metres of the centre of the transmission line but outside the distances specified in Schedule 3 (as certified by a qualified electrical engineer) require a resource consent.
  3. Buildings more than 20 metres from the transmission line are not regulated by the proposed NES. The 20-metre distance is measured from the centre of the transmission line.

Table A8: Proposed NES for transmission risks

View proposed NES for transmission risks (large table).

Schedule 1: Minimum safe distances between buildings and overhead electric line supports

Circuit voltage

Pole

Tower (pylon)

11 kV to 33 kV

2 m

6 m

Greater than 33 kV and less than 66 kV

6 m

9 m

Greater than 66 kV

8 m

12 m

Schedule 2: Safe distances for buildings and structures from conductors without engineering advice (from NZECP 34)

Circuit voltage

Maximum span length
(m)

Minimum distance beneath conductors under normal conditions
(m)

Minimum distance to the side of conductors under normal conditions
(m)

Not exceeding 33 kV AC

125

7

8.5

Exceeding 33 kV but not exceeding 110 kV AC

125

7.5

9.5

Exceeding 110 kV but not exceeding 220 kV AC

125

8.5

11

275 kV DC and 350 kV DC

125

8.5

7.5

Not exceeding 33 kV AC

250

8

12

Exceeding 33 kV but not exceeding 110 kV AC

250

8.5

12.5

Exceeding 110 kV but not exceeding 220 kV AC

250

10

14

275 kV DC and 350 kV DC

250

10

11

Not exceeding 33 kV AC

375

9.5

20.5

Exceeding 33 kV but not exceeding 110 kV AC

375

10

21

Exceeding 110 kV but not exceeding 220 kV AC

375

11

22.5

275 kV DC and 350 kV DC

375

10.5

18

All other spans

Engineering advice required

Notes:

Observance of potential conductor motion is required to ensure safe distances during construction.

Where supporting structures are not located on equal elevations, a specific engineering study may be required to ensure that distances are in accordance with Schedule 3.

Schedule 3: Minimum safe distances of conductors from buildings and other structures where specific calculation of conductor movement has been carried out (from NZECP 34)

Safe distance conditions

Not exceeding 33 kV AC (bare or covered)
(m)

Exceeding 33 kV but not exceeding 110 kV AC (bare)
(m)

Exceeding 110 kV but not exceeding 220 kV AC (bare)
(m)

Exceeding 220 kV AC or DC
(m)

A:   Vertically above those parts of any structure normally accessible to persons

4.5

5

6.5

7

B:   Vertically above those parts of any structure not normally accessible to persons but on which a person can stand

3.7

4.5

6

6.5

C:   In any direction (other than vertically above) from those parts of any structure normally accessible to persons, or from any part not normally accessible to persons but on which a person can stand

2.1

3

4.5

5

D:   In any direction from those parts of any structure not normally accessible to persons

1.5

2.5

3.5

4

E:   In any direction from the ground

Refer to Schedule 4

 

 

 

Schedule 4: Minimum safe distances of conductors from the ground

 

Vertical distance to the ground (m)

Radial distance (m)

Circuit voltage

Across or along roads or driveways

Any other land traversable by vehicles

Any land not traversable by vehicles due to inaccessibility

In any direction other than vertical on all land

Not exceeding 33 kV AC

6.5

5.5

4.5

2

Exceeding 33 kV but not exceeding 110 kV AC

6.5

6.5

5.5

3

Exceeding 110 kV but not exceeding 220 kV

7.5

7.5

6.0

4.5

Exceeding 220 kV AC or DC

8.0

8.0

6.5

5

Note: ‘Vehicles' includes mobile plant.

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