Generally, the standard splice loss for single-mode fiber is around 0. To be able to judge whether a fiber optic cable plant is good, one does a insertion loss test with a light source and power meter and compares that to an estimate of what is a reasonable loss for that cable plant. The estimate, called a "loss budget" is calculated using typical component losses for. ity check. This type of testing is the most accurate testing available and is the most accurate characterization of the fiber optic system's apability. The Contractor must utilize the correct equipment and testing techniques to gain acceptance, or the work cannot be approved.