Abstract: A method to determine an unknown, current pre-tension force in a pre-tensioned securing member having an exposed portion comprises coupling a pulling member to the exposed portion of the pre-tensioned securing member, generating pulling forces with the pulling member on the pre-tensioned securing member, measuring pulling force displacements of the pre-tensioned securing member in response to first and second applied pulling forces that are different from each other, measuring pulling force displacements of the pre-tensioned securing member in response to third and fourth pulling forces that are different from each other, determining a first relationship between the first and second pulling force displacements, determining a second relationship between the third and fourth pulling force displacements, and determining the current pre-tension in the pre-tensioned securing member by setting the first relationship and the second relationship equal to each other.

Abstract: A switch extension device comprises an elongate extension member and an actuation member. The elongate extension member has a distal end shaped to couple with an electrical switch and a proximal end for positioning remote from the electrical switch. The actuation member is coupleable to the proximal end of the elongate extension member. The actuation member is movable to move the extension member to actuate the electrical switch. Methods of operation are also described.