Frequently asked questions

 Please find below common questions and our answers for the Top Ryde to Wentworth Point cable project.

Project need, route selection and options

How does Ausgrid plan cable routes?
 Ausgrid is installing 132,000 volt cables between our substation in Top Ryde via the Meadowbank substation to a network connection point in Hill Road, Wentworth Point. These cables are replacing existing 132,000 volt cables in the area. 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 to 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.

Ausgrid started preparing to replace the cables in late 2013. This process involved engaging with local councils and Members of Parliament in the areas where the new cables could be laid. Following this initial round of consultation, the project team drew up a range of possible routes for discussion and feedback at a community workshop in early September 2014.

Workshop participants included representatives from community and local business groups, utilities and other interested community members. Information about the workshop can be found here. This information was used by Ausgrid as part of the process to refine the options with several preferred options. These preferred options were then taken to the wider community with a newsletter delivered in the areas where the cables may be laid and several community sessions were held in late November 2014. A summary of the community sessions can be viewed here. Further planning, including feedback from the community sessions, has been completed and Ausgrid selected a preferred cable route. An environmental assessment (REF) was then prepared on the preferred cable route and can be viewed via the link at right. All submissions were considered as part of the process to approve the project for construction. For further details, please see community engagement section of this project web page.

Were there a number of route options?

Yes. In addition to the preferred routes, Ausgrid investigated a number of others. Other considered routes can be viewed on this map - click here

Our investigations found that while some of the other considered routes may be constructed, Ausgrid believes the confirmed route is cost effective, minimises environmental impact and has the least construction risk. 

General project questions

What is the capacity of the new cables?
The capacity of the existing cables in summer are 235 and 302MVA. In winter 250 and 318MVA. The majority of this capacity is only rarely used under abnormal system outage circumstances.  The capacity of the new cables are 270MVA each.

This capacity has been decided when considering future load growth and the ability of Ausgrid to provide reliable supply under outage situations where other equipment is out of service.

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, there are two feeders each comprising three cables, so six cables in all.

How does Ausgrid forecast future energy needs for an area?
Ausgrid uses underlying historic local trends based on normalisation for weather and other variables as the basis for forecasting future energy needs. Ausgrid models how historic trends will be modified by econometric factors including the increase in customer connections, government policy initiatives and changes in electricity prices. This particular area is characterised by relatively flat organic growth with some block loads predicted in the short term at Meadowbank and Top Ryde of 4.9MVA and 5.6MVA respectively. 

Does this take into account future planned developments such as the North Ryde precinct activation project?
The North Ryde Precinct Activation project is factored into the forecast and is currently expected to be connected to Top Ryde substation.

Community consultation during project planning

What engagement with the community has been conducted by Ausgrid?
Ausgrid sought input from the community as we planned the new cable routes between Top Ryde substation, Meadowbank substation and a connection point on our electricity network in Wentworth Point.

Community feedback is one of the factors considered by Ausgrid to select a preferred cable route and to develop the construction program. Prior to taking this project to the community, Ausgrid plans the project so that issues such as EMF from the operation of the cables, environmental issues, and potential construction impacts on the community (such as parking, traffic and access) are considered and addressed as part of the selection of the preferred cable route and the environmental assessment of the project.

Input from the community is considered with these other factors at each project stage, including the opportunity to make a submission on the REF. The preferred cable route was then assessed under the project's Review of Environmental Factors (REF) which can be viewed via the link at top right.

All community submissions on the REF were  considered as part of the process to finalise the project for construction.

The engagement process has included delivery of newsletters to residents and businesses, community information sessions at venues near the routes, door knocks, meetings, the public exhibition of the REF and the submission process. Ausgrid has taken comments and feedback on board and made changes to the project plan where practical and efficient.

Electric and magnetic fields

What are electric and magnetic fields?
When electrical equipment is in use, electric and magnetic fields (EMF) are produced. You will find EMF in and around most households and workplaces from sources such as appliances, building wiring, office equipment and the local electricity network (including overhead power lines or underground cables). When talking about EMF in relation to whether there are any health concerns, people are generally referring to magnetic fields.

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.

What about magnetic fields and health?
Authoritative reviews have concluded that no adverse health effects from exposure to EMF have been established. However, noting the non-conclusive nature of the science and genuine concern in the community, Ausgrid design our projects with measures to minimise magnetic fields. As part of the initial planning process, Ausgrid has modelled the expected magnetic fields from the cables to demonstrate that the magnetic fields would be at levels well within Australian and international guidelines for public exposure to magnetic fields.

What are the relevant Australian guidelines in relation to magnetic fields?
The relevant Australian guidelines for magnetic fields in Australia recommend a public exposure limit of 1,000 milligauss (mG). Guidelines prepared by the International Commission on Non-ionising Radiation Protection (ICNIRP), which have been adopted by a number of countries, recommend a public exposure limit of 2,000mG.

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 are doing for this project. Ausgrid's position includes complying with all relevant national and international guidelines.

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.
 
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 cable route for the Top Ryde to Wentworth Point project has been 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. Magnetic fields are based on the current (electrical load) in the cables. The magnetic fields from the cables would vary depending on factors such as the physical installation of the cables and the load at the time. Average fields from the standard cable trench would be down to below background levels 5 metres from the centre of the trench.
Ausgrid engaged Aurecon to complete modelling for the project based on the expected loads. The full report is included in the Review of Environmental Factors (REF) for the project.

What are the levels of typical background magnetic fields?
Australian government agency ARPANSA says typical background magnetic field values measured in areas away from electrical appliances are of the order of 0.1 - 2 mG.

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.

I’ve heard that the 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.

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 generally low levels of magnetic fields modelled for theses cables, which would be well within the range normally encountered in everyday life at properties along the cable routes. These levels would also be reduced through the prudent avoidance measures Ausgrid is implementing for this project including centrally positioning the cable installation to maximise the distance to properties where practical. 

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.

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).

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 the new 132,000 Volt cables for the Top Ryde to Wentworth Point cable project in accordance with all relevant Laws and will apply prudent avoidance measures to reduce EMF levels consistent with the recommendations of WHO and ARPANSA.

Construction related questions

What would the work site look like?

A typical work site encompasses 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.

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

Yes. Access to properties will be maintained throughout the project unless we have made 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 will be on site to ensure you can safely enter onto the road/street.

How long would 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.

What hours would you be working? Would 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 will 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 would 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.

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

Generally, the exact location of joint bays along the cable routes are not be finalised until there is confirmed cable route and a contract 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 starting 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.

Restoration

What areas does Ausgrid reinstate?
All surfaces affected by the project, such as through excavation of the cable trenches are reinstated by Ausgrid, including roads and grassed areas. This process sometimes involves more than one step (see below).

When is reinstatement completed on a project?
Road reinstatement of affected areas is generally completed in two stages and starts after each section of work is finished. Excavated sections of road are refilled and temporarily reinstated to allow normal use by traffic. Once all cables are installed and tested, permanent reinstatement is done in consultation with the relevant council.

Will any street trees that may be identified as requiring removal be replaced?
Replacement planting and vegetation reinstatement, where street trees have been removed, would be completed in consultation with the relevant council or road authority.