Acceptable dB loss for fiber depends on the component you're measuring: a single mated connector pair should lose no more than 0. 75 dB, a fusion splice should stay under 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. A: Fiber optic loss refers to the reduction in signal strength as it travels through the fiber optic cable. So, how can we know the loss value on the fiber optic link? This article will teach you how to calculate the loss in the fiber. Fiber loss can be also called fiber optic attenuation or attenuation loss, which measures the amount of light loss between input and output. The total. standards. This testing will ensure that the data necessary to properly evaluate any future system malfunctions will be av nctioning. So, you drop everything and i vestigate. He's right – it is n t working.