Frequently asked questions
Animal grazing and health
Domestic animals can graze freely in a transmission line area. Scientific research has not found that transmission lines would have adverse effects on the health or fertility of pasturing animals. It has not been found that the licking of wooden towers which have been treated with creosote would have negative effects in animals. A statement on this issue has been submitted, among others, by the Department of Food and Environmental Hygiene of the University of Veterinary Medicine in Finland on 25 October 1994.
Power line marking
Power line bird markers can be used in transmission lines near the routes of migratory birds or in locations where birds nest to warn birds of the line. It is advisable to inform Fingrid, which decides on the placing of power line bird markers, of locations where birds collide with a line. Power line obstruction markers for air traffic are placed in locations required by the Civil Aviation Administration.
Thunder and lightning
The occurrence of thunder is closely associated with the nature of the prevailing weather. Fingrid is often presented claims according to which transmission lines would guide storm fronts. According to the Finnish Meteorological Institute, transmission lines do not increase lightning nor direct the movements of thunder clouds, but the lines actually increase lightning safety. Since the transmission line towers are usually higher than their immediate environment and since they are also grounded, they "attract" strokes of lightning which would strike in any case in the adjacent area. The line is so constructed that a stroke of lightning is guided through the overhead ground wire into the ground in a harmless manner. In other words, it is not advisable to stay in the immediate vicinity of a transmission line during thunderstorm. Transmission lines cannot influence the number of strokes of lightning, either. Their number depends entirely on the properties of the thunder cloud, not on the underlying terrain.
Operation of pacemakers
The electric and magnetic fields of electricity distribution structures, anti-theft equipment and metal detectors can influence the operation of cardiac pacemakers. Disturbance in a pacemaker can be reduced through adjustments and especially through the selection of an appropriate pacemaker.
Sounds caused by corona and wind
Corona discharge occurring on the surface of conductors or insulators manifests itself as a buzzing sound. The corona phenomenon is harmless to people. The phenomenon is caused by the ionisation of air in the vicinity of the surface of conductors, insulators and other similar components. The sound caused by corona is loudest in moist weather or in the winter when hoar frost accumulates on the conductors. It is practically almost impossible to prevent corona discharge completely, but since the sound is always an indication of energy losses, the goal is to minimise this phenomenon. Corona occurs mainly at the 400 kV voltage level.
High-voltage lines may also cause sounds created as a result of wind which shakes the various parts of the line such as steel towers, conductors, crossarms or insulators. These sounds occur irrespective of whether the line is live or not.
Radio and television interference
Transmission lines do not disturb FM radio transmission (VHF), i.e. the most common broadcast or local radio transmissions. A transmission line disturbs the television signal in very rare cases only. If problems occur, contact Fingrid's experts.
Fluorescent lamps and electric field
A hand-held fluorescent lamp may light up under a transmission line as a result of the electric field created by the conductors. The current travelling in the lamp is naturally much weaker than normally. The lamp glows weakly, and the light emitted from it cannot be compared to the light emitted in the normal use of the lamp. The light can only be seen when it is dusky. This purely electric phenomenon does not mean that it would cause a health hazard.
One of the properties of the electric field of a transmission line is that electrically conductive objects which are isolated from the ground and located close to the line - such as metal shovels, tools etc. - become electrically charged. Anyone working under a line also becomes electrically charged.
Usually, you do not even notice this, but when you wear footwear with a thick sole, such as rubber boots, you may feel a faint spark when you touch a grounded object, for instance a metallic fence pole. The phenomenon is the same and as harmless as the spark which is created when taking off a sweater made of synthetic fibres.
In the same way, the sparking of an umbrella, for instance, under a transmission line is harmless and caused by electric charge.