There is provided a non-intrusive movement measuring apparatus and method using wearable electro-conductive fibers. Pitches 3a, 3b and 3c with different pitch lengths are formed so that a pitch with a larger pitch length is set to have a smaller groove area ratio, and to have a larger groove wall angle \u03b1 on the obtuse angle side that is formed by a groove wall of a lateral groove 2 and the direction tangential to the thread surface. The flange includes a blade edge configured to have an initial engagement with a surface of a wallboard when the electrical box is installed in an opening of the wallboard.