Raking, planting bulbs and composting – there is a lot of autumn gardening to be done, but not many people think about pruning the trees near power lines. Lives can even depend on it, and branches that grow too high can cause system disturbances and even power outages.

There is a ministerial decree that obliges property owners to prune trees that have grown to the critical height, but this should not be the main reason for doing so. Safety is a much more important consideration because trees that are not properly cared for could endanger human lives.

Pruning is always the property owner’s responsibility. The ministerial decree says that property owners (operators) have to prune regularly if the trees approach or come into contact with the edge of the safety zone of overhead power lines.

When planting new vegetation, you must remember that you may not plant trees in the power line’s safety zone because they would endanger the power line and therefore the safety of operations when they grow.

If tree branches and twigs encroach on power lines, the local unit of the power company always has to be notified so that it can cut off power before the pruning begins in order to ensure the safety of the person doing the pruning. In these cases, the service provider will cut off power without charge.

The safety zone for bare above-ground power lines extends
1 meter in each direction for up to 1 kV of nominal voltage
5 meters in each direction for between 1 kV and 35 kV of nominal voltage, measured from the outermost conductor. This is 2.5 meters in each direction on sections of the power line that comply with the regulations for incorporated areas and extra safety
13 meters in each direction for between 120 kV and 200 kV of nominal voltage, measured from the outermost conductor.

The only trees that may be planted under electric power lines are ones whose branches will never grow any closer than two meters to the power line once the tree is fully grown.

Avoiding the danger of accidents is not the only reason for pruning trees. Branches hanging down near power lines can cause a system disturbance or a power outage in a moderate wind.

In order to limit any inconvenience for household consumers, plans will have to be made to switch off power so that pruning can be done near electric power lines. The power provider must therefore be informed, preferably in writing, of the date planned for pruning at least 30 days in advance. This should be done in a timely fashion, since safety is the primary consideration at such times. In the last resort, the service provider will do the pruning; if this happens, however, the service provider’s only concern will be the size of the safety zone, and it will not be able to pay attention to aesthetics or protecting the vegetation.