TIA-526-7:2002 (R2008)

This procedure can be used to measure the optical loss between
any two passively-connected points, including end terminations, of
a single-mode optical fiber cable piant. The optical fiber cable
plant, as the term is used here, may consist of optical fiber
cables, connectors, mounting panels, jumper cables, and other
passive components, but may not include active components.

Two methods for measuring the installed cable plant loss are
described. Method A uses optical power measurement equipment.
Method B uses an Optical Time Domain Reflectometer (OTDR). Method B
provides an indirect estimate of the loss of the cable plant, and
although calibration is possible, generally, more accurate or
reliable values may be obtained by using Method A. If the values
obtained by Method A and Method B differ from each other, the
results of Method A shall be accepted as correct. Method B is not
recommended for cable plants containing branching devices and/or
isolators.