The testing of premises fiber optic cabling links requires precise methods for referencing to obtain accurate and valid test results. Loss testing for multimode fiber cabling is specified in ANSI/TIA/EIA-526-14A. This standard contains two test procedures: Method A and Method B. This application note describes Methods A and B, and explains why Method B is the proper method for testing fiber links contained in premises networks.

This note also proposes a new test procedure as an adaptation to Method B to overcome some disadvantages associated with Method B. This new test procedure is the preferred method because it provides results conforming to Method B while offering installers more flexibility for testing fiber links with all types of connectors, including Small Form Factor (SFF) connectors. This note also details other advantages of the Method B adaptation for simplifying the testing process and reducing the opportunity for errors.