Electrical and magnetic fields

The following question crops up over and over again: Do electrical and magnetic fields from our power supply system affect our health?

Wherever current flows, electric and magnetic fields arise: constant fields (DC fields) in the case of a DC current and periodically changing fields (alternating fields) in the case of an AC current. The strength of these fields always depends on the local conditions: the voltage and current levels play a role in this, as do the height of the conductor cables and pylons or the number of circuits on the pylons. The fields are always strongest at the centre point between two pylons, because this is where the conductors are closest to the ground. The further away you get from the route, the smaller the field strengths become.

Electric and magnetic fields do not just occur in the vicinity of power lines – they are part of our daily life. All electrical devices create fields; for instance, cookers, power drills or halogen lamps. Furthermore, the earth has its own natural electric and magnetic DC field. The magnetic field of the earth becomes apparent when looking at a compass. Natural electric DC fields arise between different atmospheric layers or during thunderstorms, for example.

How these fields affect humans is something scientists have been studying for a long time. We at Amprion keep a careful eye on the results of research being conducted into low-frequency, 50-hertz fields. So far, however, these researchers have not been able to find any evidence of a connection between electric or magnetic fields from power supply installations and impairments to health. Differentiated ceilings for these fields – most recently confirmed in the amended version published in 2013 – are stipulated in the 26th Ordinance on the Implementation of the German Federal Immission Control Act (26. BImSchV): these are 500 microteslas (µT) for magnetic DC fields, 100 µT for magnetic alternating fields and 5 kV per metre for electric alternating fields with the grid frequency of 50 Hz.

There are no specific ceilings for electric DC fields and air ion concentrations in the vicinity of overhead lines. Ions are electrically charged particles that arise from the electric field around the conductor cables. Potential, significant disturbances caused by the interaction between ions and the electric field, however, must be avoided (26. BImSchV).

The magnetic and electric fields of DC and AC power lines, such as those carried on the pylons of our Ultranet project, for example, must be viewed separately. This is due in part to the fact that the effects of DC and AC fields differ. What we do know from laboratory and field tests conducted prior to commissioning Ultranet is that both the strength of the magnetic DC field and that of the magnetic alternating field will fall well below the respective ceilings set by 26. BImSchV.