Electric and Magnetic Fields (EMFs) are produced by any appliance with electric current flowing through it. That includes not only powerlines but just about every electrical appliance used in the house.
EMFs and powerlines
EMFs from powerlines depend on the amount of current flowing along the powerlines. Fields decrease in strength the further you move away from the source. Ergon Energy has documented policy and procedures relating to design and installation practices and EMFs.
Ergon Energy will address concerns about EMF exposure by:
- Keeping informed about engineering and scientific research on EMF exposure and reviewing its policies in the light of the most up-to-date research findings, with particular emphasis on the findings of eminent scientific review panels.
- Actively participating in industry and other forums that have the objective of broadening scientific knowledge of the effects of EMFs.
- Responding constructively and consistently to employee and community inquiries and referring inquirers to authoritative sources of information.
- Practising prudent avoidance (as established by good engineering and planning practice as it is applied, or is to be applied, at Ergon Energy's operating locations) in siting new generation, transmission and distribution facilities.
- Undertaking monitoring and analysis of EMF levels associated with its network.
- Prudently managing public, and Ergon Energy employees' and contractors' occupational exposure to EMFs associated with Ergon Energy's network.
Does undergrounding stop EMFs?
Putting powerlines underground does not stop EMFs. The earth does not shield magnetic fields. Design decisions such as using multiple phases (wires) and laying them closer together underground can help to reduce EMF levels. Importantly, similar design decisions can often be used with overhead wires to help cancel out magnetic fields.
Common sources of EMFs
The following table shows typical magnetic field strengths from a number of common sources including powerlines.
|Source of EMFs||Typical measurement
|Range of measurements
|Distribution powerlines (measured under line)||7||2-20|
|Distribution powerlines (measured 8 metres away)||2||0.4-4|
|33,000 volt underground cables||12 (1 metre above ground, directly above buried cable)||3 (4 metres away)|
Source: Energy Networks Association, Australia, brochure Electric and Magnetic Fields-What we know
The National Health and Medical Research Council (NHMRC) guidelines recommend the following limits of exposure:
- Public exposure to magnetic fields of 2,000 milligauss continuous per day or 10,000 milligauss for up to two hours per day
- Occupational exposure to magnetic fields of 10,000 milligauss per working day or 50,000 milligauss for up to two hours per day
- Public exposure to electric fields of 5 kilovolts per minute (kV/m) per day or 10 kV/m for up to two hours per day
- Occupational exposure to electric fields of 10 kV/m per working day or 30 kV/m for two hours per day.
More information on EMFs can be found on the following websites:
- The Australian Radiation Protection and Nuclear Safety Agency
- National Institute for Environmental Health Sciences (USA)
- EMFs.info (UK)
- World Health Organization (WHO) EMF Project
- International Commission on Non-Ionizing Radiation Protection (ICNIRP)
- International Agency for Research on Cancer (IARC)
- Energy Networks Association