| 摘要 |
PROBLEM TO BE SOLVED: To provide a fire-proof element which can surely exhibit its fire-proof function, without reducing the inner volume of an outlet box. SOLUTION: A fire-proof element 30 comprises a cylinder 32, which has an attaching part 38 to an outlet box 14 on its one end side, a thermally foamimg heat-resistant material 34 inserted into the cylinder 32 and a shape- memory alloy spring 36, which is provided in a compressed state between the thermally foamimg heat-resistant material 34 and a spring stop part 40 on the other end side of the cylinder 32. If the temperature of the shape-memory alloy spring 36 exceeds a certain value due to the heat of fire, the spring extends and pushes the thermally foamimg heat-resistant material 34 out of the cylinder 32 into the outlet box 14. |
