Strength of electric and magnetic fields around power lines
The strength of the fields around a power line depends on a number of things – for example, the amount of current being carried.
ELF fields get weaker with distance. For many power lines, the ELF fields 50 to 100 metres away are the same strength as the fields found in many homes and offices.
Even if you’re standing right below a power line, the fields are well below the public safety limits recommended in New Zealand and overseas. Similar fields can be found close to some electrical appliances.
Health effects of electric and magnetic fields
A lot of research has been done over the past 40 years to find out if the ELF fields produced by power lines and other electrical equipment could be harmful.
The research has been reviewed several times by various national and international groups. Public safety limits are based on the findings of these reviews.
Some studies suggest that there may be a link between living near power lines, or in houses with strong magnetic fields produced by other sources, and a small increase in the number of children with leukaemia. But the link might be explained by other factors, and laboratory studies don’t suggest a connection, so it is not clear whether magnetic fields pose a risk or not. If they truly do increase the risk of leukaemia, the World Health Organization considers that there would be only a limited impact on public health. While it is worth taking simple steps to reduce exposures (for example, when installing new electrical facilities), safety limits need not be lowered.
Find out more
An interagency committee monitors research into the health effects of ELF fields. Find out more at Research into non-ionising fields.
- Electric and Magnetic Fields and Your Health - a Ministry of Health publication.
- Transpower - Transpower is responsible for power transmission in New Zealand. They supply information on the field strengths found around their lines.
- World Health Organization – Electromagnetic Fields - The World Health Organization investigates the possible health effects of electromagnetic fields.
- US National Institute of Environmental Health Sciences – Electric and Magnetic Fields
The US National Institute has researched the effects of electric and magnetic fields. They published the following report in 2002.
- Electric and Magnetic Fields Associated with the Use of Electric Power: Questions and Answers (PDF, 11.5 MB) - Be aware that this report uses an older unit of measurement for magnetic fields. Also, mains voltages are different in the USA, so magnetic fields from appliances and wiring tend to be higher than in New Zealand.