Add bends as notable direction changes and apply a per-bend allowance (commonly 0. 60 m per end is common for control and instrumentation terminations, while larger power terminations may require more. This page helps you estimate how much a subsea fiber optic cable's length changes as temperature shifts from installation conditions to expected operating extremes. This value is affected by the amount of cable sag and by. Expansion and contraction occur across multiple materials that are bonded, constrained, or layered together. Each material within. Affects thermal expansion allowance. Usually 2 ends for a single cable run.