As the mutual influence of electric circuits can change after new lines are installed or old lines dismantled, certain transpositions may disappear or be added after new construction in electricity mains. In the case of a twisted line the individual conductors of an electric circuit swap places, either in their whole course (at cables) or at certain points (at overhead lines). The mutual influence of electrical conductors is reduced by transposing. The unbalance of the line, which can lead to one-sided loads in three-phase systems, is also reduced. Transposing of overhead lines is usually realized at so-called transposing pylons. Transposing is an effective measure for the reduction of inductively linked normal mode interferences.