Which apparatus is specifically designed to measure conductor sag accurately?

The dynamometer is the correct choice for measuring conductor sag accurately. It is engineered specifically for measuring the tension in cables or conductors, which directly relates to their sag when installed between two points. By using a dynamometer, linemen can quantify the forces acting on the conductor, allowing them to establish and maintain the proper sag during installation, ensuring safety and compliance with specifications.

A multimeter is primarily used for measuring electrical properties such as voltage, current, and resistance, and does not provide the necessary measurements related to physical stress or tension in conductors. A caliper is designed for measuring the dimensions of objects, such as thickness or diameter, and is not relevant for measuring tension or sag in wires. An insulation tester focuses on assessing the insulation quality of electrical components and conductors, providing no insight into their sag or the forces acting upon them. Thus, the dynamometer stands out as the specialized tool suited for the task of measuring conductor sag accurately.