According to NFPA 72, fiber-optic strands must be terminated to prevent breaking due to what factors?

Fiber-optic strands are delicate and susceptible to damage if not properly terminated. The primary reason for ensuring that they are correctly terminated is to prevent breaking due to vibration or stress. Termination involves the process of securely attaching the fiber to a connector to ensure that the light signals can pass through without loss or interference.

If the fibers are not terminated adequately, they can become brittle and may easily break under mechanical stress or vibration, which could occur during installation, maintenance, or normal operations. This makes it critical for technicians and installers to follow proper procedures when terminating fiber-optic cables to maintain the integrity of the fire alarm systems that rely on these components.

While improper techniques and mismatching termination fittings can indeed lead to issues as well, the specific emphasis in the context of this question relates mostly to how vibration and stress contribute to the risk of breaking. Therefore, while all the options mentioned do contribute to potential problems, the most critical factor to address to prevent breakage is ensuring that the strands are terminated correctly to withstand environmental stresses.