A circuit breaker

A circuit breaker, comprising a casing, wherein the casing comprises:

• a main body and an end cover attached to an end of the main body;
• an annular tube extending from the end cover on an outside of the end cover, wherein the annular tube comprises a desiccant holder configured to house a desiccant configured to remove moisture from a gas inside the casing when the desiccant is housed in the desiccant holder;
• a rupture device configured to regulate pressure of the gas housed inside the casing, wherein the rupture device is detachably mounted to the annular tube at an end thereof remote from the end cover, and wherein a spacing defined by the desiccant holder and configured to house the desiccant is accessible from an end of the annular tube which is detachably attached to the rupture device;
• wherein upon detachment of the rupture device an opening is formed on the annular tube, and wherein the desiccant, when mounted in the desiccant holder, is accessible from said opening.