A device connectable to a power line conductor includes an electrically conductive insulated first winding of wire wound into at least two turns having a first and a second end. The first end is configured to be attached to a first power line conductor. An electrically conductive insulated second winding of wire wound into at least one turn having a first end connected to the second end of the first winding of wire and a second end is configured to be attached to a second power line conductor. A switchable connecting device is configured to move between a first position connecting the first and second power line conductors in series, a second position connecting the first winding of wire in series with the first and the second power line conductors, and a third position connecting the first and second power line conductors and the first and second windings of wire in series.