While there has been some “buzz” about Optical Time Domain Reflectometer(OTDR)testing for premises cabling since the publication of TSB-140, Additional Guidelines for Field-Testing Length, Loss and Polarity of Optical Fiber Cabling Systems, many agree that the test is usually not necessary for the relatively short links found in a customer-owned network, and may merely add unnecessary expense and complexity.
When testing an optical premises network, the key measurement criterion is insertion loss, or attenuation. This is effectively measured by using a power meter and light source. If the attenuation is within the limits of the allotted power budget, the system will work. OTDRs measure Raleigh backscatter, not absolute loss.
Supporters of OTDR testing in the premise environment believe that testing with an OTDR can help identify microbends that could potentially cause a problem; as well as help document the system for future verification. However, visual inspection is usually the best way to locate breaks or bends. While there may be some minor advantages in performing OTDR testing on premise cabling, the added cost usually outweighs the benefits.