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. FOA has a online Loss Budget Calculator web page that will calculate the loss budget for your cable plant. But what exactly sets a fibe optic connector apart in terms of its merits? The primary purpose of a fiber optic connector is to terminate the ends of fiber optic cables, ensuring they can be int rconnected reliably with minimal optical loss. The "loss of a connector" is defined as a "connection loss" caused by a mated pair of connectors. The loss of connectors on a patchcord or short cable. Optical loss (for connectors), sometimes called attenuation, is simply the reduction of optical power induced by transmission through a medium such as a pair of fiber optic connectors. Unfortunately, it is not a simple answer and depends on several factors.