A large percentage of new structured fiber cabling system are tested against project or manufacturer-specific limits rather than those we find in ISO/IEC, TIA or EN (Cenelec) standards. This knowledge base article does not focus on the “why” but on the “how to”. If we measure the loss of a large number of links with a single embedded connection, and then one with two, four, or more connections, we will find that loss is not a linear function of the number of embedded connections. Instead we find the loss of two connection is less the double the values of one connection, and the loss of four connections is less than double the value of two connections. There are technical reasons for that. Manufacturers of cabling systems consider those, when they define the test limit which must be met in order to receive a system warranty. This creates a challenge for the installer when he tries to create a custom limit in the CertiFiber PRO, because the situation varies depending on the mix, type/grade and number of connectors.
Manufacturers have developed apps for smart phones, spreadsheets, and online line tools to calculate the limit. This limit was then used, in a post-analysis process, to Pass/Fail measurement from the field, and it was not obvious to the installer at the time of test whether the link would pass or not. Obviously an unsatisfactory situation.
For this example, we assume that you using Commscope’s smartphone app cCalc, which can be downloaded from http://www.commscope.com/Resources/Apps/
Also, download the little Windows App (no install needed, simply run it) from here.
This app will allow you to select the given combination of connecting hardware and splices and calculate the limit. The little tool will then calculate the correct Custom Limit for the CertiFiber to test links of any length.
For a different combination of connectors, cassettes, splices, and fibers, the process needs to be repeated.