Dowsing & EMF
Electric and magnetic fields
Electric and magnetic fields (EMF) are produced wherever electricity or electrical equipment is in use.
EMFs in and around the home are produced by anything with electric current flowing through it, such as powerlines running from the street to your home, the home wiring system and electrical appliances. Most household appliances operate on 240 volts, so electric fields are low.
In the workplace, electric fields and magnetic fields may be produced by nearby powerlines, factory machinery, computers, lights, photocopiers, electrical cabling, etc.
Electric and magnetic fields in and around the home can be produced by anything with electric current flowing through it, including nearby powerlines, your home wiring system or electrical appliances in use in the home. However, generally, powerlines contribute little to the electrical fields that can be measured inside a house or office. This is because the walls of the building, in fact any solid object, create a shield from the electrical field. A typical house generally shields at least 90% of the electrical fields from outside.
magnetic fields from powerlines.
Both high voltage lines and distribution lines produce magnetic fields. In many cases, high voltage lines are constructed on easements where building is not permitted.
Magnetic fields associated with powerlines depend on the amount of current flowing along the line and the distance from the line.
Fields rapidly decrease in strength with distance, therefore inside a house, magnetic fields from nearby powerlines is usually similar to that from wiring and appliances.
The following table shows typical magnetic field strengths from a number of common sources, including powerlines. Fields are measured in a unit 'milligauss'. To give you an idea of the relative strength of EMFs, the following guide shows the typical magnetic fields from appliances and under powerlines.
Common sources of EMF typical measurement(in Milligauss) range of measuremen(in Milligauss)
Electric stove 6 2-30
Personal computer 5 2-20
Television 1 0.2-2
Electric blanket 20 5-30
Hair dryer 25 10-70
Fridge 2 2-5
Toaster 3 2-10
Kettle 3 2-10
Pedestal fan 1 0.2-2
Distribution powerlines (under line) 10 2-20
Distribution powerlines (8 metres away) 2 0.4-4
33 kV underground cables (directly above buried cable) 12 (1 metre above ground) 3 (4 metres away)
Pad mounted distribution transformer 2 (at 5 metres) 1-20 (10 metres to close up)
Major zone substation 2 (at substation fence) 1-6 (at substation fence)
Modular substation 1.5 (at substation fence) 0.5-3 (at substation fence)
Transmission powerlines (under line) 20 10-200
Transmission powerlines (at edge of easement) 10 2-50
(Appliance measurements taken at normal user distance)
Owing to variations in the design of electrical appliances and the loadings on powerlines, the levels of magnetic fields can vary. The table above is based on a consistent set of measurements undertaken by power authorities in Australia, using similar techniques and protocols to overseas measurements. Because of the difference in appliance design and voltage overseas, there can often be different levels shown in overseas publications.
The National Health and Medical Research Council (NHMRC) guidelines recommend the following limits of exposure*:
Public exposure to magnetic fields 1 000 milligauss continuous or 10 000 milligauss for up to 2 hours/day
Occupational exposure to magnetic fields 5 000 milligauss (for a working day) or 50 000 milligauss for up to 2 hours/day
Public exposure to electric fields 5 kV/m continuous or 10 kV/m for up to 2 hours/day
Occupational exposure to electric fields 10 kV/m for a working day or 30 kV/m for 2 hours/day
ENERGEX requires that all of its powerlines comply with these exposure guidelines. The fields encountered from ENERGEX powerlines by members of the public are only a small fraction of these limits.
* Note that these exposure limits are based on established or predicted effects of exposure. Although some statistical studies suggest an association between exposure to 50 Hz fields and cancer, others do not. Not only is this association not proven, but present data does not provide any basis for health risk assessment useful for the development of exposure limits.
significance of field levels quoted in epidemiological studies
Is there something significant about the 4mG magnetic field level often quoted in the media?
The significance of 4mG is that this value is used as a boundary to define the exposed group in some scientific studies, not as a safety threshold.
A typical home in ENERGEX's distribution area generally has a background magnetic filed (away from appliances) that ranges from 0.5mG to 2mG. Most ordinary appliances produce higher localised magnetic fields.
Several EMF epidemiological studies have used 2, 3 or even 4 mG as a cut off point to define broad categories of exposure. Below this level, subjects are considered "unexposed", and above this level they are considered "exposed". The significance of 4 Mg is that this value is used as a boundary to define the exposed group in some scientific studies, not as a safety threshold.
the health debate
ENERGEX relies on advice provided by State health bodies and authoritative reviews of electromagnetic field research to determine the status of possible human health effects.
Other forms of electromagnetic energy
Electric and magnetic fields from powerlines are often confused with microwaves and X-rays.
Microwaves are energy waves which cause heating when absorbed into tissue, such as microwave ovens. For communication purposes, microwaves are concentrated into low power beams, which are directed at a receiver. If a person is exposed to high levels of microwaves for long periods of time, then health effects can occur from heating of the body's tissue. Australian Standards for the limits of exposure to microwaves are designed to avoid this effect.
X-rays are another form of electromagnetic energy involving very high energy waves. They produce effects in living systems because the energy they carry is so great it can break molecular bonds. This is why there are strict safety regulations in place to limit exposure to X-rays.
Low frequency electric and magnetic fields associated with the use of electricity are different from these forms of energy. They are not absorbed like microwaves and cannot break molecular bonds.
ENERGEX's approach to EMF
In response to community interest in electric and magnetic fields (EMF), ENERGEX has, and will continue to provide balanced and factual information about EMF.
EMF are produced wherever electricity or electrical equipment is in use. In and around your home EMF are produced by anything with an electric current flowing through it, such as powerlines running from the street to your home, your home wiring system and electrical appliances.
What is ENERGEX doing about EMF?
ENERGEX maintains contact with a number of bodies and committees which regularly meet to discuss and evaluate any new research into EMF.
ENERGEX conducts its own monitoring and analysis of EMF levels associated with its network in South East Queensland.
ENERGEX has staff available to answer questions and provide information to the general public regarding EMF. Telephone 13 12 53.
The Australian electricity industry and ENERGEX practice prudent avoidance when designing the electricity network system. Prudent avoidance means that where feasible or reasonable, powerlines are located away from people.
ENERGEX operates all powerlines in its distribution area within the guidelines set by the National Health and Medical Research Council.
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