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What are Electric & Magnetic fields and why are people concerned about them?


Electric and magnetic fields (EMFs) are a basic form of nature, generated by electricity and found almost everywhere. In nature such things as sun, lightning and static electricity create them. Man-made fields are found wherever people use electricity, such as near powerlines and domestic appliances. The strength of the fields decrease as you move away from their source, just as the heat you feel from a campfire decreases with distance.

EMFs from power lines and electrical equipment are different in their nature and in the way they interact with the body from electromagnetic radiation originating from radio waves, microwaves and cellphones.

In recent years there have been concerns that these fields may have harmful effects on health. Despite of all the studies that have been carried out it is still not clear whether the fields pose any health risks.

Reference Levels for occupational and public exposures to electric and magnetic fields – ICNIRP* (2010) guidelines.

  Reference Level – Magnetic flux density
Exposure characteristics Microtesla (µT) Milligauss
Occupational 1000 10000
General Public 200 2000

Source: Ministry of Health. 2013. Electric and Magnetic Fields and Your Health. Wellington: Ministry of Health

*The International Commission on Non-Ionizing Radiation Protection (ICNIRP) is an international body and is recognised by the World Health Organisation (WHO) for its expertise in the area of EMFs.

 

Frequently Asked Questions

If I live near a high voltage power line, am I exposed to dangerous field levels?
Measurements on power lines in New Zealand have shown that even directly beneath the line, EMFs are well below recommended exposure limits.

Does a transformer on the street affect exposures in my house?
Magnetic field levels around small kiosk transformers decrease to low levels within 2-3 metres, and have no effect on field levels in nearby houses.

If I am concerned about possible health effects, what simple steps can I take to reduce my exposure to EMF’s in my home?
In the home, fields are higher near operating electrical appliances, meter boards and fuse boards. Some simple ways to reduce exposure include the following:

  • Switch off appliances when not in use.
  • Refrain from standing in front of the microwave oven while in use.
  • Be aware of handheld appliances such as hairdryers and electric razors as the fields are closer to your body.
  • Keep your clock radio beside the bed at least an arm’s length away from you.
  • Switch off electric blankets when in bed (but do not do this if the electric blanket is used to remedy health problems).

 

Who to Contact

If you would like to know more information on EMF’s please refer to:

Or contact us on telephone 0800 508 098, or email info@networktasman.co.nz

 

Measurements on Power Lines

Network Measurement at device Measurement 1m away
Zone Subs (Fence) 1.5 µT  
     
Under 66kV Line 0.5 µT (1.5m above ground)  
     
Under 33kV Line 1.5 µT (1.5m above ground)  
     
Under 11kV Line 0.5 µT (1.5m above ground)  
     
Under 11kV & 400V Line 0.5 µT (1.5m above ground)  
     
11lV/400V Overhead Sub (Transformer) 1.5 µT  
     
11kV/400V Padmount 30 µT  3 µT
     
Andelect 1.5 µT  0.5 µT
     
Service Box 8 µT  1 µT

 

Measurements at Home

Domestic Measurement at device Measurement 1m away
Portable Radio 1 µT 40 nT
     
Portable Fan > 100 µT 2 µT
     
Hairdryer 40 µT  
     
Electric Shaver > 100 µT  
     
Rechargable Shaver 5 µT  
     
TV (CRT) 4 µT 200 nT
     
Computer Screen (CRT) 2 µT 40 nT
     
Plug Adaptor > 100 µT 80 nT
     
Extractor Fan 3 µT 80 nT
     
Electric Blanket 2 µT  
     
Computer Screen (LCD) 1.5 µT 300 nT
     
Electromagnetic Cooktop 8 µT 40 nT
     
Clock Radio 80 µT 40 nT
     
Meter Box 6 µT 60 nT