Jetta M. Pyatt, RCDD, Siecor Corp.
Problem
Your customer requests that you certify a fiber-to-the-desk installation in accordance with industry standards and procedures. The installation was undertaken using the new 568SC duplex SC connector, and the customer wants to ensure not only that the horizontal link meets attenuation requirements but that polarity between transmit and receive fibers is correct.
Solution
To certify a fiber-to-the-desk link, the proposed American National Standards Institute/Telecommunications Industry Association/Electronic Industries Association-568A standard requires that the horizontal link be tested in one direction and at one wavelength. This draft standard requires the link to have an attenuation of less than or equal to 2.0 decibels and recommends that a one-jumper reference be used in accordance with the TIA-526-14A test procedure (originally approved in 1990).
While polarity can be easily verified by visual inspection and by following the connection rules recommended by the standard, you can test for polarity at the same time you check attenuation, reducing testing time. Typically, optical links are tested one fiber at a time; however, with a 568SC connector you can simultaneously test two fibers (a circuit pair). Using two optical sources and two meters, or two optical test sets (combined source and meter), you test one fiber in one direction and the second fiber in the opposite direction, in the same manner that an actual system operates.
Procedure
1) To set up the reference and perform the test, you need two simplex ST-to-SC test cords and two simplex SC-to-SC test cords. Also, you need two 568SC (duplex SC) clips to transform the simplex SC connectors to a 568SC.
2) On the hybrid test cords, label the SC end OAO and the ST-compatible end OB.O On the SC-to-SC test cords, label one SC connector OAO and the other OB.O
3) Establish the reference by using the two ST-compatible-to-SC test cords.
4) Disconnect the SC connector from each meter. Attach the SC-to-SC test cords to the meters using the connector labeled A. Field assemble the 568SC connectors using the 568SC clips?the 568SC connector comprises an A connector and a B connector. Place the properly labeled connector into the side of the clip that has the same label.
5) Perform a power check to ensure the new test cords are of receive a reading for the odd-numbered fibers; and another individual (with a test set and 568SC test cord) will receive readings for the even-numbered fibers at the outlet.
6) If both individuals are getting a reading, then the polarity has been properly established during installation. If neither individual is receiving light, it is most likely that the SC connectors or adapters have not been installed in the proper orientation.
