What is a characteristic of splice closures in fiber-optic installations?

A characteristic of splice closures in fiber-optic installations is that they need to accommodate the actual bend characteristics of the optical fiber. Fiber-optic cables are sensitive to bending; excessive bending can lead to signal loss or damage to the fibers. Therefore, splice closures are specifically designed to ensure that the fibers are protected while allowing them to maintain their bend radius specifications. This minimizes stress on the fibers and ensures optimal performance of the optical system.

In contrast, while splice closures are often made to withstand various environmental conditions, including being waterproof, it’s not restated in the most definitive way as necessary regardless of conditions. The other options present alternatives that are less relevant to the primary function of splice closures. For instance, simply being made from a specific material like aluminum doesn't necessarily align with the essential requirement of accommodating fiber bends. Similarly, the context of installation, whether underground or otherwise, can vary based on design decisions and terrain, not as a defining feature of splice closures themselves.