AbstractOne of the failures related to gas‐insulated switchgear is caused by the poor contact between conductors. This causes breakdown between the contact and the wall of chamber, initiated by the small discharge due to the poor contact.In this paper, the modeled experimental apparatus for the contact portion of the gas‐insulated switchgear assumed a rod‐to‐plane gap with small arc current. The influence of the arc current on the breakdown into the chamber was investigated experimentally, and the breakdown mechanism between the contacts and the wall was studied.It was clarified that the breakdown voltage between the contact and the wall decreased by increasing the current, and the small arc current in the contact portion played an important role in the breakdown between the contact and the wall.The reduction ratio of the breakdown voltage increased with increasing gap length of the small gap. The breakdown voltage was different depending on the duration of the small arc