A device for treating an exhaust gas containing particles includes: an exhaust gas line, an emission electrode and an electric supply line for the emission electrode. The electric supply line is at least partially surrounded by an electric insulator and the electric insulator has an outer diameter, the electric insulator extending from the exhaust gas line substantially in the direction of the longitudinal axis of the exhaust gas line. The outer diameter measures at most 20 mm in the terminal region towards the longitudinal axis.