|Electric field||Magnetic field|
|Formation||As soon as a device is connected to a power socket, even if it is not switched on.||As soon as current flows.|
|Intensity determined by:||Voltage (Volt)||The amount of current flowing (Ampere)|
|Intensity measured in:||Kilovolt per metre (kV/m)||Microtesla (µT)|
|Limits (CH)||5 kV/m||100 µT (exposure limit)
1 µT (installation limit)
Sources: The following content is reproduced with the kind permission of the Swiss Research Foundation for Electricity and Mobile Communication at the ETH Zurich. www.emf.ethz.ch
Measurements and calculations
Cooperation with research
Swissgrid has entered into a partnership with the Swiss Research Foundation for Electricity and Mobile Communication (FSM), a non-profit research foundation at the ETH Zurich. The FSM promotes research on technological, biological, health-related and social issues in the context of electromagnetic fields of radio and electricity technologies. The foundation also provides consulting for the authorities, companies and organisations, hosts conferences and imparts expert knowledge to the general public.
Unfavourable weather conditions in particular, such as rain, hoar frost or wet snow, can cause local electrical discharge in power lines. In electrical engineering, this process is known as corona discharge. The phenomenon can produce noises described as crackling or humming.
In Switzerland we have an emissions limit of 55 decibels in residential areas (45 decibels at night), which must be adhered to by law. The noise pollution from a busy street is over 80 decibels. Where necessary, Swissgrid employs all technical means to limit the corona effect. Corona noises are not present in underground lines.
The following movies show the sound intensity of high voltage power lines compared to more common ambient noise:
Environmental impact assessment
As part of the approval process (UVP), the environmental impact assessment examines whether a project complies with the legal regulations for environmental protection. The environmental impact assessment report (UVB) is the basis for the examination. As the client, Swissgrid is responsible for the preparation and submittal of the UVB documents. However, an independent, professionally qualified office is normally commissioned to prepare the UVB. Various issues are dealt with in the report, including noise, non-ionising radiation, water, soil, contamination, forest, biotope and vegetation, fauna and habitat, landscape and visual character, cultural monuments and archaeological sites.
Environmental supervision (UBB) looks after and monitors environmental concerns during construction and supports the client in the legally compliant and environmentally compatible execution of the construction project. In the process, it ensures compliance with environmental laws, regulations, guidelines, instructions and requirements of the planning approval decision. They advise and support the participants, observe and evaluate environmental problems on the construction site and ensure legally compliant execution of the project.