Electric and magnetic fields (EMF)

Electric fields

Electric fields can be present in any appliance plugged into a power point that is switched ‘on’. Even if the appliance is ‘off’ and the power point is ‘on’ an electric field will be present.

Electric fields are shielded by most objects, including trees, buildings and even human skin and their strength reduces rapidly as you move away from the source.

You may have seen people demonstrate how fluorescent tubes ‘light up’ when they are held under high voltage powerlines. A fluorescent tube works when an electric field inside the tube causes discharge, either as normal from the mains electricity supply or from an external electric field like that produced by a powerline. 

The electric field created by the powerline can cause a very small current to flow through the tube and this creates a weak glow. You can sometimes get the same effect in a dark room by holding one end of a fluorescent tube and rubbing your foot on a carpet to generate static electricity.

Magnetic fields

Magnetic fields are only present when electric ‘current’ is flowing. The strength of a magnetic field depends on the size of the current. Like electric fields, the strength of magnetic fields drops off quickly as you move away from the source.

While electric fields can be shielded, magnetic fields pass through most materials. As electric fields are naturally shielded, the electricity network generally contributes very little to the electrical fields measured inside a home or office building. For this reason most discussion on EMFs usually focuses on magnetic fields

Just like electrical appliances and wiring in your home or office, electrical equipment on an electricity network, such as transformers or overhead and underground powerlines has current flowing through it and produces electric and magnetic fields (EMFs).

The level of magnetic fields from the electricity network depends on the amount of current/electrical load, the way the network is configured and the distance from the equipment. The level of magnetic fields is not directly related to the voltage. It is a common misconception that the higher the voltage, the higher the magnetic fields. For example, low voltage powerlines can produce higher magnetic fields than high voltage transmission lines.

It is also a common misconception that by installing powerlines underground the EMFs are eliminated. The ground around an underground powerline provides shielding from electric fields, but it does not shield from magnetic fields.

Because underground powerlines are closer to ground level, they can have similar or even greater magnetic fields to the same powerlines installed overhead on poles.

The magnetic field levels of electrical appliances and equipment on the electricity network can vary depending on its specific electrical rating and the actual current/electrical load, the wiring/cable configuration and distance from the source.

The attached table shows typical electric and magnetic fields measurements from a number of common sources in homes, offices and the community. These fields are measured in a unit called ‘milliGauss’ (mG). The table provides a guide on the relative levels of EMFs we all generally experience in our day-to-day activities.

Electric and magnetic fields table

This table shows levels of EMFs experienced around the electricity network and from common household appliances.
File size 104kb | Download

Appliance measurements were taken at typical distances experienced by users.

The two internationally recognised exposure guidelines come from ICNIRP and IEEE.

• International Commission on Non-Ionizing Radiation Protection (ICNIRP) 2010
• International Committee on Electromagnetic Safety, Institute of Electrical and Electronics Engineers (IEEE) 2002

The Australian Radiation and Protection and Nuclear Safety Agency's (ARPANSA) advice is, “The ICNIRP ELF guidelines are consistent with ARPANSA’s understanding of the scientific basis for the protection of the general public (including the foetus) and workers from exposure to ELF EMF."

Electricity has been used in Australia for 100 years and there is no doubt that everyone in Australia is exposed to electric and magnetic fields on an ongoing basis.

Whilst the balance of scientific evidence is against EMFs resulting in adverse health effects, we recognise there are still concerns in the community about exposure and take seriously our responsibility to help address these concerns.

We will continue to:

• provide balanced, accurate information to our employees and customers, including EMF measurements and advice
• design and operate our electricity system within recognised international EMF health guidelines and to continue following an approach consistent with the concept of prudent avoidance
• monitor engineering and scientific research, overseas policy development and major reviews of scientific, medical and engineering research regarding EMF and health
• cooperate fully with any bodies established by governments in Australia to investigate and report about power frequency EMF.

Prudent avoidance was a policy recommended by former Chief Justice of the High Court of Australia, Sir Harry Gibbs. It was a recommendation of an inquiry he conducted into the problems faced by the electricity industry in relation to electric and magnetic fields (EMF) back in 1991.

He defined prudent avoidance as doing what can be done without undue inconvenience and at modest expense to avert the possible risk to health from exposure to new high voltage transmission facilities. In practical terms this means that when designing new transmission and distribution facilities, consideration should be given to practicable low cost measures that can reduce EMF exposure.

The findings and recommendations contained in the Gibbs Report are consistent with the positions adopted by us and the Energy Networks Association.

The debate over whether electric and magnetic fields EMF) have any effect on human health began in the 1960s. Since then, many hundreds of scientific studies have been undertaken around the world into the effects of EMF and their possible relationship to human health. The studies have looked at a wide variety of possible health consequences. Ausgrid relies on advice provided by health bodies to determine the status of any possible human health effects.

Australian Radiation and Protection and Nuclear Safety Agency's (ARPANSA) public information on the issue says the results of all EMF studies to date have indicated either no association or a weak association with adverse health effects. ARPANSA says association does not mean causation and advises that.

“The scientific evidence does not establish that exposure to the electric and magnetic fields found around the home, the office or near powerlines causes health effects.”

The World Health Organization (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 will continue to monitor the results of scientific studies, and the findings of reports and reviews conducted across the world. This is only a snapshot of a large amount of information available on EMF from ARPANSA. Please visit www.arpansa.gov.au or contact www.who.int for more details.