A DC circuit breaker includes a case, two fixed contacts, two movable contacts, a bypass plate electrically connecting the two movable contacts, a moving block to move the bypass plate, a moving block biasing member to bias the moving block in a direction away from the fixed contacts, a thermally responsive member, a latch, a shutter, and a shutter biasing member. The thermally responsive member deforms when an installation surface equals or exceeds a prescribed temperature. The latch restricts movement of the moving block by locking the moving block when the thermally responsive member is in a pre-deformation state. The latch cancels the restriction of the movement the thermally responsive member deforms. The shutter is insertable between the fixed contacts and the movable contacts. The shutter biasing member constantly biases the shutter in a direction to be inserted between the fixed contacts and the movable contacts.

A DC circuit breaker includes a case, two fixed contacts, two movable contacts, a bypass plate electrically connecting the two movable contacts, a moving block to move the bypass plate, a moving block biasing member to bias the moving block in a direction away from the fixed contacts, a thermally responsive member, a latch, a shutter, and a shutter biasing member. The thermally responsive member deforms when an installation surface equals or exceeds a prescribed temperature. The latch restricts movement of the moving block by locking the moving block when the thermally responsive member is in a pre-deformation state. The latch cancels the restriction of the movement the thermally responsive member deforms. The shutter is insertable between the fixed contacts and the movable contacts. The shutter biasing member constantly biases the shutter in a direction to be inserted between the fixed contacts and the movable contacts.

A temperature-dependent switching mechanism is equipped with a bimetal snap-action disc and a spring snap-action disc, which carries a movable contact part, the bimetal snap-action disc and the spring snap-action disc being captively held in an annular frame.

In a temperature-dependent switch having a switching mechanism that has a movable contact part which cooperates with a stationary counter contact and is moved by a spring part to which the movable contact part is electrically conductively connected, the switching mechanism produces an electrically conductive connection between the stationary counter contact and a second counter contact in a temperature-dependent manner. The switch is provided with an arc-shielding plate, which has no mechanical function, is arranged on an upper surface of the spring part and covers sections thereof.