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Elektromagnetische Felder

Limit values for stationary low-frequency and direct current installations

To date, electric energy has been transmitted from the power plant to the consumer almost exclusively through high-voltage lines carrying alternating current at a frequency of 50 hertz. In the course of the energy transition, high-voltage direct current (HVDC) installations are also planned in Germany.

Limit values for power supply installations in accordance with the 26th Federal Immission Control Ordinance on electromagnetic fields (26th BlmSchV)
Installation TypeElectric Field Strength E
(kilovolt per metre)
Magnetic Flux Density B
(microtesla)
HVDC (0 Hz)-500a
Low-frequency installation (50Hz)5100
a With amending the 26th BlmSchV in August 2013, also the immissions of high voltage direct current (HVDC) installations have been regulated by law for the first time. The limit has been chosen so as to avoid interference with electronic implants by static magnetic fields.

In the amended 26th ordinance implementing the Federal Immission Control Act (26. BlmSchV) limit values have been laid down for low-frequency electric and magnetic fields as well as for static magnetic fields. The 26th BlmSchV entered into force in 1997 and was amended in August 2013. In addition to limit values for stationary installations for the transformation and transmission of electricity, it also contains precautionary requirements.

The "Bund/Länder-Arbeitsgemeinschaft für Immissionsschutz (LAI)" (Federal/Länder Working Group on Immission Protection) has published information on the implementation of the Ordinance on Electromagnetic Fields with the purpose of promoting a uniform enforcement by the authorities, but also of providing operators or those affected with minimum requirements.

Bases for the limit values

Low-frequency fields

Upon exposure of the human body to low-frequency electric or magnetic fields, electric fields and currents are produced in the tissues. When certain – frequency-dependent - thresholds are exceeded, nerve and muscle cells can be stimulated. The limit values are set so as to safely prevent established health effects.

The basic parameters for the limit values are the induced (i. e. produced in the body) electric field strengths (see established health effects through fields generated by power supply systems). The values for the maximum permissible immissions, acting upon the body externally due to stationary installations, are derived from these field strengths.

Static fields

The health effects of static fields that can be directly attributed to biological effects are known only for very high magnetic field strengths.

Occasionally even weaker magnetic fields pose an indirect risk as they exert forces on magnetic objects and may cause interference with implants. The limit value for static magnetic fields has therefore been determined so as to also avoid interference with implants. No limits have been set for static electric fields.

Compliance with limit values

The limit values for 50-hertz fields apply to places intended for not only temporary presence of humans. These include

  • housing
  • workplaces
  • schools and
  • hospitals.

Low-frequency installations covered by the 26th BlmSchV have to be erected and operated in a way that the limit values for these places are met even when the installations are operating at maximum capacity. Other immission sources (such as other low-frequency installations) also have to be taken into account.

Direct current installations located at places intended for temporary or permanent human presence have to comply with the relevant magnetic field limits. The electricity grid operators are responsible for ensuring compliance with limit values in practice.

DIN standards

In addition to legal regulations, technical details for the design of high-voltage lines have been defined in various DIN standards. They specify minimum clearance distances for example, between the live parts of high-voltage lines and buildings. These specifications, however, are made primarily for fire protection and operational reasons and not for reasons of radiation protection.

State of 2016.12.14

© Bundesamt für Strahlenschutz