Electric and Magnetic Fields (EMFs) are a basic form of nature, generated by electricity and found almost anywhere. In nature such things as sun, lightning and static electricity create them.
Electric and magnetic fields
The Safety Concern
Man-made fields are found everywhere people use electricity such as near power lines and domestic appliances. The strength of fields decreases as you move away from their source, just as the heat you feel from a campfire decreases with distance.
Electric and Magnetic Fields 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 all of 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
Miscrotesla (µT)
Milligauss (mG)
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 Electric and Magnetic Fields.
Measurements on Powerlines
Network
Measurement at Device
Measurement 1m Away
Zone Subs (Fence)
1.5 µT
-
Under 66kV Line
0.5 µT (1.5 above ground)
-
Under 33kV Line
0.5 µT (1.5 above ground)
-
Under 11kV Line
0.5 µT (1.5 above ground)
-
Under 11kV & 400V Line
0.5 µT (1.5 above ground)
-
11kV/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
-
Rechargeable Shaver
0.5 µT
-
TV (CRT)
4 µT
200 nT
Computer Screen
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
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, electric and magnetic fields are well below recommended exposure limits.
Does a transformer on the street affect exposure in my house?
Electric and magnetic field levels around small kiosk transformers decrease to low levels within 2-3 meters 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 infront of the microwave 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.
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