In a method, a first electrode is moved to contact with first paired ends of first paired conductor segments. Next, a second electrode is moved opposing the first paired ends Electric conduction is established between the first electrode and the second electrode via the first paired ends of the first paired conductor segments to weld the first paired ends of the first paired conductor segments based on the electrical conduction therebetween. Next, the second electrode is moved opposing second paired ends of second paired conductor segments while the first electrode is kept in contact with the first paired ends. Electric conduction is established between the first electrode and the second electrode via the welded first paired ends and the second paired ends to thereby weld the second paired ends of the second paired conductor segments based on the electrical conduction therebetween.