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Magnetic & electric fields of low frequencies (ELF)

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Magnetic & electric fields of low frequencies (ELF)

What kind of radiation is emitted by hybrid cars?

The hybrid car, as its name implies, combines propulsion based upon energy from traditional fuel and from electric energy that accumulates during motion. Electric currents used in the electric part of propulsion while driving create a surrounding of low frequency magnetic fields. This radiation is defined as non-ionizing radiation from the electricity grid in the Extremely Low Frequency radiation range (ELF).

The Ministry of Environmental Protection and Health Ministry recommendations on the maximal radiation exposure level permissible from electrical appliances are available in the article on electric grids.

The power of magnetic fields created in hybrid cars differs from car to car according to the automobile make and model, and there are even differences between different cars from the same manufacturer and the same model. Also, the distribution of the power of the fields, in the car’s interior, varies from place to place within the car.

At present there are different positions regarding levels of magnetic fields created by hybrid cars and their radiation hazards. Also, the scientific knowledge existing on this subject is limited and there are no clear guidelines regarding their use.

In Israel, the issue of hybrid cars was addressed at length by the Ministry of Environmental Protection which authorized their use. The Ministry conducted extensive tests to examine the exposure to non-ionizing radiation inside hybrid cars and inside regular cars.

A link to data on radiation exposure in hybrid cars (Hebrew) in Israel may be viewed, detailing the average yearly level of exposure in each seat in the various cars checked, according to a stringent assumption of 18 hours average weekly time spent in the car.

What radiation is emitted from a server room?

Relatively low strength electrical currents and voltages exist in servers and therefore the non-ionizing radiation in their vicinity is at a very low level (servers are not a special source of radiation, that is, the radiation is not generated by transmitters and antennae intentionally, but rather exists as a by-product).

There are magnetic fields on the electricity grid frequency in the vicinity of power sources that use servers. However, at a distance of one meter or more from them, the field level is mostly below the level of a few milliGauss, and complies with the Ministry of Health and Ministry of Environmental Protection recommendations for maximal permitted level of exposure to magnetic fields from electrical appliances. 

What is the minimal distance allowed between electrical installations (such as power lines or transformers) and residential homes?

The Ministry of Environmental Protection determines the criteria for distances separating electrical installations from sensitive land use sites such as residences, educational institutions, etc. These criteria depend on a large number of factors, such as the type of installation, the electricity that flows through it, the distance and height of the land use site, relative to the wires through which the electricity flows, the layout of the wires, etc.  The Ministry of Environmental Protection website lists the criteria for determining distances between electrical installations and residences, for each type of installation (Hebrew). 

 

Recommendations of the Ministry of Environmental Protection and the Ministry of Health regarding the maximal allowed level of radiation from electrical installations are:

  • 2000 milligauss for short-term exposure (momentary exposure)

  • 4 milligauss daily average for the busiest day (continuous prolonged exposure).

Chronic exposure, or continuous prolonged exposure, is defined as exposure of more than 4 hours daily for more than 5 days a week.  Residences, offices, educational institutions, commercial and industrial buildings, etc., are considered locations of chronic exposure.

 

For precise data on radiation levels, an authorized radiation surveyor may be summoned, from the list of authorized surveyors on the Ministry of Environmental Protection's website (Hebrew). 


 
 26.10.15

Do powerline adapters emit stronger or weaker radiation than Wi-Fi (routers and access points)?

Powerline network adapters (working via the electricity network) use information modulation technology (modulation, information construction) on infrastructure wires for transmitting internet communications over short ranges over the home electrical infrastructure.

The modulation is done over a wide range of frequencies, determined by the rate of data transmission and from which the radiation frequencies which could develop during data transmission was determined.

Network adapters utilize two end units, one for receiving the information from the router and data modulation over the electrical infrastructure wires, and another for receiving it in another location.

The radiation levels produced by this technology are very low, because the signals passed through the electricity wires (in house walls) are relatively weak, and because rather than the radiation being produced by a broadcasting antenna (as exists in Wi-Fi technologies), it develops in a “parasitic” manner in the vicinity of the electricity wiring in house walls or in the vicinity of electricity sockets (and the adapters themselves), that do not act as efficient antennae.

Various measurements made for internet powerline network adapters, have shown levels of radiation below one nano-watt (one billionth of a watt) per cm2 at a distance of 1 meter from the electrical wiring – less than one thousandth of the radiation levels produced at a distance of 1 meter from a wireless routers and access points.

It should be noted that there are powerline network adapters that also use wireless technology (for making a wireless connection for cellphones, tablets and computers in the target area), and in these cases they also produce radiation at the 2.45 and 5 GHz frequencies (like the radiation from Wi-Fi networks).

 

To what degree does exposure to electromagnetic radiation increase when the electrical panel is located inside the house?

Levels of exposure to magnetic fields in the vicinity of electrical panels are mainly dependent on the size of electric currents and the way the conductors are arranged inside the panels. Distance from electrical panels also has a large effect.

The overall value of electrical currents developing inside home electrical panels can reach tens of amperes, as a function of the type of consumer connection to the electric company and the degree of electricity consumption. Exposure levels in the vicinity of the panels may reach several tens of milligauss and even more than this. However, as the distance from the electrical panels increases, exposure levels drop sharply.

 

The recommended method of reducing exposures to magnetic fields from electrical panels, according to the precautionary principle, is by keeping sufficient distance from the electricity cupboard. Thus, at a distance of 1 meter from the electrical panel, exposure levels drop to a few milligauss. In addition, the location of the electrical cupboard should not be in the walls of residential rooms (in which people may spend prolonged time periods).