An arc extinguisher for low voltage switchgear, switching in air, includes a universally applicable variable attachment for adjustment of the arc extinguisher chamber to meet increased demands. The attachment is in the form of a chimney-like arc extinguisher chamber extension, for increasing the volume of the arc extinguisher chamber. It represents a moulded piece with a lower outline which exactly matches the outline of the arc extinguisher chamber cover, normally located on the arc extinguisher chamber and with an upper outline, identical to the upper outline of the switchgear housing for mounting the arc extinguisher chamber cover. Any number of attachments may be used in a stacked manner.