Fiber optic closures are used to protect optical fibers in a network. Fiber optic closures are integral part of the network that can be installed anywhere in the outside plant or inside plant. Fiber optic closures deployed in customer premises, Central office/telephone exchange, or other protected environments, shall meet minimal environmental protection criteria and fire-spread ratings.
Image courtesy: Ronhui Fiber Optics
Typically, the expected worst case operating environment for a fiber optic closure is from -40°C and 70°C. This temperature range is applicable to the cables as well. The environmental thermal resistance defined by the atmospheric temperature varies from region to region. The temperature ranges applicable for fiber optic components intended to be used in the Middle East Asia may be different for the ones intended for Canada.
Russian specifications for fiber optic components typically demands extremely low temperatures such as -60°C. However, some of the Russian specifications demands a higher temperature of +60°C only. I have seen some specifications from Kuwait that demands compliance to +85°C. Thus an optical fiber closure installed at these temperatures shall also meet the temperature ranges that are prevalent in the country. the closure shall not experience any functional degradation that could affect the performance of the closure.
Underground environments do not experience the same level of severity as the above ground outdoor environment, thus the operating environment for a closure located in an underground environment is defined at temperatures between -30°C and 60°C (ITU-T L.13, Performance Requirements for Passive Optical Nodes: Sealed Closures for Outdoor Environments) and the closures shall not experience any functional degradation that could affect the performance of the closure.
Under extreme environmental and mechanical conditions to which a closure may be subjected in certain deployment configurations, to include flood water or chemical exposure, submersion in ice, and exposure to steam or fire. Under such extreme conditions, the closures shall not experience any functional degradation that could affect the performance of the closure.