Patent ID: 6897760

Claim:
A circuit breaker, comprising: a power supply side fixed contact and a load side fixed contact facing the power supply side fixed contact, a movable contact for bridging the power supply side fixed contact and the load side fixed contact, and a main housing including an intermediate housing with a lower portion in which said power supply side fixed contact and load side fixed contact are disposed, and a lower housing in which said movable contact is disposed, said lower housing being fitted in the intermediate housing for covering the lower portion thereof and having front and rear walls with thin wall portions and arc gas emission holes, each of said front and rear walls having a center portion and a guide wall in the center portion, said thin wall portions being located on two sides of the center portion and having a thickness greater than that of the guide wall and less than that of the center portion so that when the electrical current is broken and arc gas is generated in the main housing, the thin wall portions bend outwardly to allow the arc gas to flow out through a gap formed by bending the thin wall portions and the arc gas emission holes.