Continuing the thread of measurement uncertainty in fiber optics, this month I discuss measuring the loss of an installed fiber optic cable plant. Optical loss, tested with a light source, power meter and two reference cables, is the most common measurement in fiber optics.
Last month, I wrote about measurement uncertainty and metrology, the science of measurements. This month, I get more specific and cover the uncertainty of some basic fiber optic measurements, starting with optical power.
There is no question today’s fire alarm systems are more complex than they were 20 years ago. More panels are addressable, which means programmers, installers and inspection and testing personnel need to be better qualified.
Once a technician has spliced a fiber optic cable, he or she must test the splice to verify it is strong and has low loss. The technician must add the test data to the documentation for future reference and present it to the cable plant owner to verify the installation has been done correctly.
“The only thing worse than training employees and losing them is to not train them and keep them.” I’ve heard Wayne D. Moore cite this Zig Ziglar quote many times during presentations, and, for me, it always hits home.
In its basic form, commissioning means testing every device, process and procedure in an integrated systems solution to ensure the final specification operates as planned and according to the owner’s design.
I have often described the reliability of a fire alarm system installation as dependent on four elements: design, equipment, installation and maintenance. I have also explained that the last two elements contribute the most to a fire alarm system’s operational reliability.
Last month, we discussed “dark fiber” and how most outside plant installations include more fibers than are needed at the time of installation. Later, those fibers will be used for expanding service capacity or leased out to provide income.
We all know that fire alarm systems that are tested and maintained on a regular basis are more reliable. According to NFPA 72, National Fire Alarm and Signaling Code, the owner is responsible for inspections, testing and maintenance as well as any alterations or additions to the fire alarm system.
In 2012, the National Fire Protection Association adopted NFPA 3, Recommended Practice on Commissioning and Integrated Testing of Fire and Life Safety Systems. Since then, it has been split into two separate documents.
Everyone tenses up in anticipation as they hear the countdown, “three, two, one.” Then there’s an extremely loud BOOM and blinding light. Sparks fly everywhere, and smoke fills the test area. Laughter and perhaps even a high five frequently follow.
The last two columns covered fiber optic power meters, test sources and the reference cables you need to test the loss of installed fiber optic cable plants. This month, I discuss using these instruments properly and how to determine if a tested cable plant passes or fails the test.