Frequently asked questions

 Please find below commonly asked questions about the North Shore cable project and our answers.

 

Project need, route selection and options

1. How were the routes selected?

The North Shore cable upgrade project involved installing 132,000 volt cables between our substation in East Lindfield to other substations at Castle Cove and Artarmon. These cables replace existing 132,000 Volt cables.

In planning for all of our projects, the health and safety of the community and our staff is the highest priority.

There are a number of things we look at when planning cable routes, including:

  • Location of existing underground utilities like water and sewer pipes, gas mains, telecommunications cables, and other electricity cables. These are found by undertaking trial holes and referring to Dial Before You Dig (DBYD) diagrams.
  • Community impacts like visual amenity and noise.
  • Traffic. We aim to select streets that are not major thoroughfares to avoid disruption to motorists and minimise night work which affects residents.
  • Environmental impacts, for example, vegetation removal or wildlife habitat.
  • Cost effectiveness. We try to minimise cost so that these savings are passed on to our customers.
  • Technical requirements including cable rating and network security.
  • Locating the cables in an accessible place for routine and emergency maintenance.

2. Why are cables being laid through East Lindfield when similar cables were laid in 2007?

Ausgrid’s substation at East Lindfield (known as a subtransmission switching station) was commissioned in 1967 and is a key part of the electricity network serving Sydney’s North Shore. There are a range of 132,000 Volt electricity cables running from this substation, to supply other areas on the North Shore, including substations at Artarmon (Willoughby subtransmission substation) and Castle Cove (Castle Cove zone substation).
To ensure a reliable supply of electricity there are a number of cables between substations that can be used to provide alternate supply when there are unexpected faults or when maintenance is underway.
Two of the four cable connections between East Lindfield and Artarmon were replaced as part of the 2007 project. This project replaces the other two cable connections between East Lindfield and Artarmon and the two cable connections between East Lindfield and Castle Cove. The existing cables have been in service for more than 35 years and needed to be replaced before they become unreliable. The new cables to Artarmon also provide some additional capacity to meet forecast higher electricity demand and provide supply at 132,000 Volts for substations at North Sydney and Crows Nest.

3. Are there other route options, including installing the cables through bushland areas rather than residential streets?

Yes. Ausgrid investigated alternative routes, such as through national park and council managed bushland, laying cables along the bed of Middle Harbour, or a combination of some of the above and alternative streets. These alternative options would avoid some residential streets in East Lindfield but not other suburbs along the routes. There are no routes between East Lindfield and Artarmon and East Lindfield and Castle Cove that completely avoid residential areas.

Our investigations found that while some of the alternative routes may be constructed, Ausgrid’s option could be delivered safely for the community at the lowest cost, with minimal environmental impact and the least construction risk.

As the levels of EMF (magnetic fields) from the new cables would be extremely low and similar to levels already found in residential areas, Ausgrid did not consider this a reason to re-route the cables.

Some of the alternative routes would also cause construction impacts for other properties. This included residents who would be located near a ‘boring’ site or areas where trees would be cleared. A number of the potential routes also involved re-routing into streets currently not on a route of an existing 132,000 Volt cable.

In the Artarmon area, Ausgrid has been able to respond to community concerns about the cable route in and around Artarmon Reserve that will link in with our existing cable tunnel under the Gore Hill Freeway. The route we consulted with the community about included a section through bushland in Artarmon Reserve. Ausgrid believed that the cables could be laid there without significant impacts on the bushland.

Through the community sessions and discussions with the local bush care group and interested residents, Ausgrid understood the importance of this area to the community and the desire that it was not disturbed. Ausgrid reviewed the decision to nominate a route through the bushland rather than the alternative of continuing along the residential street to the end of Chelmsford Avenue next to existing 132,000 Volt cables. Ausgrid determined that the technical issues behind the original decision could be managed and the route was amended to continue the cable route to the end of Chelmsford Avenue and enter the reserve at this location.

General project questions

1. What is the capacity of the new cables?

The existing cables between East Lindfield and Artarmon and East Lindfield and Castle Cove that we are replacing under this project have a capacity of approximately 175MVA (Mega Volt Amperes). The new cables between East Lindfield and Castle Cove have a similar capacity of approximately 175MVA to the existing cables. Each set of cables between East Lindfield and Artarmon have capacities of approximately 270 MVA and 230MVA. The capacity of the cables to Artarmon is higher to meet the long-term forecast demand for electricity in this part of the lower North Shore. Loads factoring in approximately 20 years of load growth have been used for the calculations of predicted magnetic fields for the proposed new cables.

2. What are feeders and how many will be installed?

Feeders are sets of cables that run between different points on the electricity network. For this project, each feeder comprises three cables. For this project, two feeders (six cables) have been installed for each route, so four feeders (12 cables) in total.

Community consultation during project planning

Prior to taking this proposal to the community, Ausgrid planned the project so that issues such as health from operation of the cables, environmental issues, and potential construction impacts on the community (such as parking, traffic and access) had been considered and addressed.

The engagement process included delivery of newsletters to residents and businesses along both routes, community information sessions at venues near the routes, and a range of meetings with residents and other stakeholders such as councils and Members of Parliament.

Ausgrid has also worked to address community questions and concerns in writing and via individual visits to residents’ homes. During visits to residential homes, Ausgrid has provided more detail on the project and demonstrated the current magnetic field levels, including those from existing 132,000 Volt cables and other power lines, cables and private equipment/appliances to help community members better understand the work.

In addition to providing further information requested by the community, the consultation process has resulted in a number of changes to the project to address community requests, such as further magnetic field (EMF) mitigation measures and a route change around remnant bushland in Artarmon Reserve. The process has also enabled Ausgrid to address individual concerns raised by some residents through provision of additional information.

Ausgrid does take comments and feedback on board and makes changes to the project plan where practical and efficient.

Electric and magnetic fields

1. Does higher voltage mean higher magnetic fields?

It is a common misconception that because the cables have a high voltage, they would also have high magnetic fields. The size of the magnetic fields produced from the cables (and any other electrical equipment) is dependent on the level of current, not the voltage. The voltage is the pressure behind the flow of electricity (that produces an electric field) and the current is the quantity of electricity flowing (producing a magnetic field). For example, low voltage power lines that are found in many residential streets will often produce higher magnetic fields at the property boundary than the proposed 132,000 Volt cables.

2. Will there be “radiation” from these electric cables?

Electric and magnetic fields (EMF) can be confused with radiation like medical X-rays and ultraviolet sunlight because the term “radiation” is often used to refer to two very different things. “Radiation” is a scientific term that simply describes how energy travels from a source. A rock tossed into a pond is a source of energy where it lands and causes ripples that “radiate” out in circles - that is “radiation.” Television and radio broadcast towers, power lines, appliances, and home wiring all have fields that radiate out from the source.

The term “radiation,” however, is also used to refer to very different fields, such as those from medical X-rays or the ultraviolet part of sunlight. Exposure to fields from those sources can damage the DNA in cells, which can lead to cancer. A good example is overexposure to sunlight, which can lead to skin cancer. The damage occurs by a process called ionization, so those fields are categorized by science as “ionizing” radiation.

EMF from power lines, electrical appliances, and home wiring, however, is not strong enough to damage DNA, so it is not the same as radiation from medical X-rays or the ultraviolet part of sunlight. EMF, therefore, is categorized as “non-ionizing.” The capability to damage DNA is determined by the “frequency” of the source. Frequency is measured in Hertz (Hz). For a source to produce enough energy to damage DNA, it must be at a frequency of approximately ten thousand billion Hz. EMF from the use of electricity is at a frequency of only 50 Hz.

3. Is the National Health and Medical Research Council (NHMRC) Guideline outdated and no longer valid?

No, although dated compared to international standards, Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) advises it considers that the NHMRC Guideline remains suitable for use until withdrawn and/or superseded by an ARPANSA Radiation Protection Series publication. The more recent international standard by ICNIRP was released in 2010 and has a public exposure limit of 2,000 milligauss.

4. I’ve heard that these magnetic field limits are not low enough?

There is no scientific basis to establish limits below those that exist presently (including the rescinded and draft Australian guidelines and International guidelines).

ARPANSA advises that:

The evidence does not allow health authorities to decide whether there is a specific magnetic field level above which prolonged exposure is a hazard to human health.

The World Health Organization (WHO) advises that:

EMF exposures below the limits recommended in the ICNIRP international guidelines do not appear to have any known consequence on health.

 and

policies based on the adoption of arbitrary low exposure limits are not warranted.

ICNRIP advises that regarding limits below the guidelines:

 that available data are insufficient to provide a basis for setting exposure restrictions.

5. I've heard that Sweden has a limit of 2mG. Is that true?

No. Sweden has a government regulation which requires video display units to have a magnetic fields less than 2 mG at the operator's position, which is assumed to be 1 metre in front of the screen. This standard only applies to video display units, but has been widely misunderstood and applied to circumstances for which it is not appropriate. It was never intended to be a limit on general EMF exposures.

6. I have been told and read that there is a connection between magnetic fields and cancer, so I would like some reassurance about these cables.

Research on electric and magnetic fields (EMF) and possible health effects has been conducted worldwide for over 44 years. This includes over 2,900 studies at a cost of more than $490 million. All of the research is comprehensively reviewed by Australian and international inquiries and expert panels established solely for the purpose of trying to determine whether or not human exposure to EMF is related to adverse health effects.

In 2011, the International Agency for Research on Cancer (IARC) classified power frequency magnetic fields as 'possibly carcinogenic'. IARC advises that the term 'possibly' has no quantitative significance and is used simply as a descriptor. This descriptor applies where there is limited human evidence, a lack of evidence in animals and no biological explanation. There are currently 275 agents listed as 'possibly carcinogenic'.

Other prominent reviews include National Institute of Environmental Health Sciences (NIEHS) 19992, National Radiation Protection Board (NRPB) 20043, World Health Organization (WHO) 20074 and International Commission on Non-Ionising Radiation Protection (ICNIRP) 20105. None of these reviews have confirmed the existence of any adverse health effects at levels below Australian and international guidelines limits.

The Australian Radiation Protection and Nuclear Safety Agency (ARPANSA), as part of the Health and Ageing Portfolio, is a Federal Government agency charged with responsibility for protecting the health and safety of people, and the environment, from EMF. ARPANSA advises that:

The scientific evidence does not firmly establish that exposure to 50 Hz electric and magnetic fields found around the home, the office or near power lines is a hazard to human health.

Currently there is no evidence that exposure to electric fields is a health hazard (excluding electric shock).

The WHO advises that:

Despite the feeling of some people that more research needs to be done, scientific knowledge in this area is now more extensive than for most chemicals. Based on a recent in-depth review of the scientific literature, the WHO concluded that current evidence does not confirm the existence of any health consequences from exposure to low level electromagnetic fields.

Ausgrid's position on EMF has been adopted in the light of authoritative reviews having concluded that no adverse health effects from exposure to EMF have been established, but recognising that there is, within the community, some genuine public concern about the issue which must be addressed.

A further consideration is also the low levels of magnetic fields modelled for the new cables, which are well within the range normally encountered in everyday life at properties along the cable routes.

These levels have been reduced through the prudent avoidance measures Ausgrid has planned for this project including optimising the arrangement of the cables in the trench and joint bays to minimise magnetic fields and centrally positioning the cable installation to maximise the distance to properties where practical. Please refer to the table below (link in question nine) showing predicted magnetic fields.

7. Isn’t EMF the same as smoking/asbestos 40 years ago?

The comparison between magnetic fields (EMF) and smoking, asbestos and other such agents is not a valid one. The Journal of Risk Research recently published an article by ARPANSA’s Ken Karipidis titled “Is the Risk Comparison Made by the Public Between EMF and Smoking or Asbestos a Valid One?”, April 2007. In relation to whether the comparison is valid the paper states:

In applying the Hill model for causation in the associations between smoking and lung cancer and asbestos and mesothelioma, the evidence for a causal relationship between these two agents and cancer is overwhelming. The same cannot be said, however, for exposure to ELF EMF and adverse health effects. Human studies have largely been inconsistent apart from the childhood leukaemia findings which, although they raise some concern, have to be viewed with caution. The small observed increased risk in childhood leukaemia has not demonstrated a convincing dose response relationship and although unlikely to be due purely to chance, could be attributed to selection bias or possibly some unknown confounding factor.

In addition, experimental studies have not supported the biological plausibility of the association between ELF EMF and adverse health effects or cancer, in particular. There is no consistent evidence that exposure to ELF EMF has lead to the initiation or promotion of cancer in animal studies or shown to be mutagenic in vitro (IARC, 2002b).

It may be argued that all the compelling evidence we have for the causal relationship between smoking/asbestos and cancer was not known many years ago, for example, the clear link between smoking and lung cancer was not established till the late 1950s. It is true that current scientific knowledge may change with time and that criticism of the past scientific evaluations of smoking and asbestos are largely made in retrospect.

Much of the knowledge that is used to assess physical agents today such as epidemiology and DNA research was not available prior to 1950. In fact only since the 1980s has epidemiology improved methodologically. Even cancer registries which could potentially have been introduced 100 years ago are a relatively recent public health measure.

Furthermore, exposure to smoking and asbestos showed clear signs of shorter-term ill-affect i.e. smokers experienced excessive coughing and asbestos workers showed physical signs of asbestosis such as restricted breathing. Exposure to environmental levels of ELF EMF does not indicate such physical signs of an ailment and although people have reported a range of symptoms from being exposed to EMF fields, the symptoms experienced are generally without well-defined measurable endpoints and so the relationship with exposure to ELF EMF is difficult to make.

In scientific research, causality must always remain a matter of judgment based on all the available evidence in accordance with a structured framework such as the Bradford Hill criteria described above. Application of the considerations in the criteria do not establish a cause and effect relationship for ELF EMF and adverse health effects, such as that found between smoking and lung cancer, and asbestos and mesothelioma.

Expert committees that have reviewed the scientific evidence on the subject have consistently concluded that present data are insufficient to show that exposure to ELF EMF poses a human health hazard (National Institute of Environmental Health Sciences, 1998; Advisory Group on Non-Ionising Radiation, 2001; IARC, 2002; International Commission on Non-Ionizing Radiation Protection, 2003).

 

8. Will the levels of electric and magnetic fields (EMF) from the proposed cables be safe and comply with relevant Australian health guidelines?

Safety is Ausgrid’s highest priority. The North Shore cable upgrade project was planned on the basis that the new 132,000 Volt cables can be operated safely in the community and this is Ausgrid’s first and most important consideration. The new cables will operate well within Australian and international health guidelines, with very little, if any change to magnetic fields in properties along the cable route. Based on modelling by Aurecon for the new cables, the predicted magnetic fields from the cables at 10 metres would generally be consistent with typical background levels.

In response to community concern about magnetic fields and health, and in line with our position of prudent avoidance, Ausgrid has implemented several mitigation measures to substantially reduce the magnetic fields.

9. What are the predicted EMF levels for this project, have they changed?

Modelling of the magnetic fields from the proposed cables has been completed independently of Ausgrid by consulting firm Aurecon. Aurecon’s first report was issued in August and has subsequently been updated to reflect Ausgrid’s annual 20 year electricity network forecast and the latest measures to minimise magnetic fields. The latest annual forecast produced lower load predictions than the previous year’s review which was used for the initial modelling. This is consistent with the AEMO (Australian Energy Market Operator) NEFR (National Electricity Forecasting Report) which has shown a recent drop in demand and a lower than previously forecast growth into the future.

Modelling is conducted based on predicted forecast operation of the cables up to 20 years in the future, which factor in load growth over this time. This means that the magnetic field levels indicated in the report will likely be higher than those actually experienced for the majority of the time.

Results from the report show that magnetic fields from the new 132,000 Volt cables would comply with relevant Australian health guidelines and are well within the range normally encountered in everyday life at properties along the routes. For example, for the East Lindfield to Castle Cove cables, the predicted magnetic fields at 10 metres from the centre of the cable installation are less than 0.5mG for the cable trench and 0.6mG for joint bays. For the East Lindfield to Artarmon cables, the predicted magnetic fields at 10 metres from the centre of the cable installation are 0.8mG for the cable trench and 2.4mG for joint bays.

A summary of the results can be found here. The full Aurecon report is part of the environmental assessment (Review of Environmental Factors or REF) that was put on public exhibition in late January 2014.    

10. Will the magnetic fields produced from the new cables add to the existing magnetic fields?

Adding magnetic fields from two sources is not a straight forward matter of adding the field strengths. Magnetic fields are vectors and have direction and size. Usually, if two fields come from different sources, the orientation is random and will vary over time. If there are two magnetic fields with random orientation, one field has to be only slightly larger than the other to dominate the average result. For example, if one field is half the size of the other field, it makes only a 10% difference to the total. Therefore, in practice, if we want to know what the field is at a given place, we need usually assess the field from the biggest single source only, and don't need to consider all the smaller contributions.

11. What is Ausgrid’s approach to EMF?

While there remains a lack of scientific consensus about whether electric and magnetic fields (EMF) can cause any adverse health effects, Ausgrid understands that there is concern in the community about EMF around high voltage cables. We take seriously our responsibility to help address these concerns by providing balanced and accurate information about EMF, by taking reasonable steps to limit exposure and by operating all our electrical installations prudently within Australian health guidelines. We also regularly monitor research and policy into EMF and health.As there is a lot of research and studies regarding health and EMF, Ausgrid is guided by Australian Government agency ARPANSA, which takes a whole of science approach in relation to electricity and health. This includes implementing prudent avoidance measures where practical and feasible, as we have done for this project. Ausgrid's position includes complying with all relevant national and international guidelines.

12. What is Ausgrid’s approach to prudent avoidance?

Ausgrid’s approach to prudent avoidance involves providing balanced and accurate information about operating our network prudently within Australian health guidelines, and closely monitoring scientific research on magnetic fields in relation to health concerns. In this project, Ausgrid is implementing technical solutions to reduce magnetic fields when they fit within the scope of prudent avoidance such as optimising the arrangement of the cable installation.

13. What magnetic field mitigation measures are you planning for this project?

The following are steps proposed to mitigate the level of magnetic fields (EMF) from the proposed cables:

  • Install the feeders in double circuit configuration
  • Arrange feeders in a trefoil configuration
  • Optimise phase arrangement for the trefoil configuration
  • Invert one of the trefoil circuits
  • Place feeders in carriageways rather than footways
  • Reconfigure the downstream network to more equally balance loads across adjacent Willoughby feeders
  • Optimise phase arrangement for the flat and joint bay configurations
  • Centralise cable locations between properties along the route as far as reasonably practical.

Magnetic fields can be reduced by using reverse phasing between circuits and arranging the three phases of the circuit in ‘trefoil’. Trefoil arrangement, when compared to a flat arrangement ‘localises’ the magnetic fields due to the closer phase separation of the phases.

14. Can’t you install metallic shielding around the cables to reduce EMF?

Ausgrid has adopted the principle of prudent avoidance for this project and proposed a number of measures that have resulted in predicted low levels of magnetic fields. Given that the modelled magnetic fields are at low levels and the significant cost of installing metallic shielding, Ausgrid does not believe shielding a prudent measure for this project.

15. What setback distance is considered safe?

There is no specific safety ‘setback’ from cables. As the level of magnetic fields depends on the level of current running through the cables, and each set of cables can operate with very different current, a standard setback is not relevant. Ausgrid focuses on understanding the levels of magnetic fields from cables when they are in operation to ensure they are within relevant health guidelines and to implement measures that meet prudent avoidance principles. Further, there is no scientific basis to establish limits below those that exist presently (including the interim Australian guidelines and international guidelines).

16. Does Ausgrid guarantee that the cables will be safe and not affect my health?

The use of electricity is an essential part of life in a modern society. Whenever electricity flows Electric and Magnetic Fields (EMF) are produced. Ausgrid operates a large electricity distribution network and is committed to ensuring the safety of both its workforce and the general public in the operation of this network. Ausgrid bases its policy with respect to EMF on advice from relevant bodies such as the World Health Organisation (WHO) and the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA).

Ausgrid has designed, constructed and will operate the 132kV cables planned for East Lindfield to Artarmon and East Lindfield to Castle Cove in accordance with all relevant Laws and will continue to apply prudent avoidance measures to reduce EMF levels consistent with the recommendations of WHO and ARPANSA.

Construction related questions

1. What will the work site look like?

A typical work site will encompass a number of vehicles including an excavator, a truck to remove the spoil and other trucks containing equipment and crews. On-site personnel including work crews and traffic control staff will also be present. Traffic conditions will also be changed temporarily. Click here to view an indicative work site.

2. Will I be able to get my car out of the driveway while you are working in my street?

Yes. Access to properties is maintained throughout the project unless we have make prior arrangements with you. If crews are working directly in front of your property, they will work with you to help you exit as quickly as possible. Generally, steel plates are placed over the trench to allow cars to drive over the trench – this can take around five to ten minutes to organise depending on the work being undertaken. Traffic controllers are on site to ensure you can safely enter onto the road/street.

3. How long will work take outside my home?

Generally trenching proceeds at a rate of 20-30 metres per day so this means that crews should pass your home in around two-three days. However, this rate depends on how much rock is in the ground as this takes longer to excavate.

4. What hours will you be working? Will you be working at night?

We generally work standard construction hours – from 7am to 6pm Monday to Friday and 8am to 1pm on Saturdays. However, there may be times when we need to work at night, for example, on major roads and intersections which helps to avoid major traffic disruptions. In these cases, high-impact noise such as jack hammering will cease by 11pm. We advise you in advance of work in your street so you will know when work will start and finish, and the approximate duration of work.

5. Will there be a joint bay outside my house, and if so, what does that mean for me any my family?

The exact location of joint bays along the cable routes is not finalised until a contract is awarded. The contractor then prepares a detailed project design, including the location of all joint bays. We make contact with all residents adjacent to the joint bays well in advance of work to start to discuss the construction process. Generally joint bays remain in place for a number of months but access to properties is maintained. This amount of time is required to allow specialist crews to undertake staged cable jointing work inside the bay.

6. Will this project affect the bicycle paths around Artarmon Reserve?

During construction, control measures are in place to ensure the safety of cyclists. This may require closure of bike paths during construction hours. Steel plates are used to cover the trench between shifts and these areas are signposted. The trench is temporarily restored with hot mix asphalt which is equivalent to a normal road surface (except with seams down either side of the trench). At a later date the road is reinstated to council specifications.

7. Will trees be protected during construction?

Augrid generally engages an independent arborist to complete a report along the revised route. The arborist report specifies how the construction team are to work near trees along the route.

Restoration

1. What areas will Ausgrid restore?

All affected areas, including grass sections within Artarmon Reserve, Barcoo Reserve and East Lindfield Park, are restored to their previous condition. This process may involve more than one step.

2. When will the restoration be done? 

Road resurfacing is completed in two stages and starts after each section of work is finished. Excavated sections of road are refilled and temporarily resurfaced to allow normal use by traffic. Once all of the cables have been installed and tested, permanent resurfacing is done in consultation with the relevant council.

3. How will Ausgrid reinstate the affected section through East Lindfield Park and Artarmon Reserve?

Ku-ring-gai and Willoughby Councils have been consulted regarding replacement planting and vegetation reinstatement at East Lindfield Park and Artarmon Reserve.

4. How will Ausgrid reinstate the affected section at Scott's Creek?

Replacement planting and vegetation reinstatement at Scott’s Creek in consultation with Council has been completed.

5. Will any street trees that have been identified as requiring removal be replaced?

 Replacement planting and vegetation reinstatement, where street trees have been removed, is completed in consultation with the relevant council.