Metal ignition wires are widely used in power arc tests on insulator sets and similar. Finer metal ignition wire is preferred from the point of view of influence on the apparatus tested. However, if the metal ignition wire is too fine, the arc cannot be sustained. To perform a power arc test successfully, therefore, the metal ignition wire needs to have some degree of thickness. With these requirements in mind, we proposed a novel arc ignition method that allows the use of an extra fine wire by leading to the pre-arc in a current of several dozen amperes. In this paper, the sustainment characteristics of arc ignited from an extra fine copper wire using this novel method were investigated with a gap between the rod electrodes. The results showed that the kiloampere-class arc with a gap length of meter class could be ignited through pre-arc from the copper wire that is 0.03 mm in diameter with a voltage of 12 or 24 kV. The influence of the copper wire thickness on arc characteristics was also studied by comparing the arcs ignited by this novel method with those ignited by the general method where copper wires exceeding 0.3 mm in diameter were used.