For normal fiber broadband, the ideal range of light attenuation is -20dBm to -25dBm. Monitoring the light level is a fundamental practice in fiber network engineering to ensure the signal remains strong enough for reliable detection. Because optical power levels. At TREND Networks, we are frequently asked how much loss is allowed when conducting testing on fibre optic cabling. Unfortunately, it is not a simple answer and depends on several factors. So how do you determine acceptable loss? When testing fibre optic cabling, determining acceptable loss is. 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. The optical power budget is the minimum light energy required for transmitting signals successfully to the receiver through fiber optic fibers.