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Fiber Optic Testing & Safety

Many people who install or maintain fiber optic cables do not take proper safety precautions to avoid the many hazards that can be caused by fiber optics. They assume that because optical fiber doesn't carry electricity, it is not dangerous. Unfortunately, accidents occur because of this assumption.

There are three categories involved in safety protection issues when working with fiber optics. These are eye protection, fiber fragment control, and safe use of chemicals.

Hazards of Working with Fiber Optics

When working with fiber optics, a person's eyes can be damaged by the transmitting of light. Anyone looking directly at the transmission of such frequencies can suffer loss of visual acuity or blind spots because the beam is focused on the retina.

The fibers themselves are a very serious hazard since they are small pieces of glass. If possible, use a dark mat that is chemical-resistant and as resilient as the work surface so when small fragments fall, they can be seen easily and picked up with tweezers.

When a worker is trimming, stripping, or cutting fibers, tiny fragments can penetrate the skin and become embedded, causing a serious irritation. Ingested fibers can cause internal damage since they are light enough to float in air. Because of this, workers should not eat or drink in a fiber optic work area since a fiber scrap could fall onto their food or in their drink.

There are also many chemicals and solvents used in cleaning and splicing fiber optics, which can be hazardous.

Fiber Optic Safety Rules

When working with fiber optics, all employees performing any splicing or termination activities should always wear safety glasses with side shields. Any other employees or site managers entering the work area should wear safety glasses with side shields also.

Unless an employee is absolutely sure there is not a light source at the other end, they should never look directly into the end of the cable. A power meter can be used to make certain the fiber is dark.

While working with fiber optics, the worker needs a well-ventilated and well-lit work area. Workers must avoid smoking while working with fiber optics.

Also, all food and beverages should be kept out of the work area. Workers can wear disposable aprons to keep fiber particles off their clothing. Before leaving the work area, an employee should always check their clothing for pieces of stray fiber, and if any are found, they can remove it with double-sided tape.

A worker should wash their hands thoroughly before touching their eyes, and contact lens wearers should wash their hands before touching their lenses. Workers should also read all instructional material before handling chemicals.

A disposable container that can be tightly closed must be used for fiber scraps. When finished with a fiber optic job, all cut fiber pieces should be disposed of properly along with any used chemicals and containers. The work area should be thoroughly cleaned when job is completed.

Following these simple fiber optic safety rules can keep workers healthy and the work environment safe for all employees.

Once you install and terminate fiber optic cables, it's time to test them. A test should be conducted for each fiber optic cable plant for three main areas: continuity, loss, and power. To do this, you'll need a fiber optic power meter. Here's a quick guide to fiber optic power meters and how they work.

Before Using a Power Meter

There are a few things you should do to prepare before using a fiber optic power meter. First, read the manual and run some practice tests with your power meter before going onto the job site. Next, prepare documents showing how and where all your cables are installed. Don't depend on memory because you can easily lose track of your cables, especially if it's a large project. Also, create a worksheet to document your testing data. Some power meters have a memory feature for keeping your data. These come in handy for large projects as well.

Use Safety Precautions

It's important to follow safety precautions while testing fiber optic cables with a power meter. Wear eye protection when working with high-power cables. Even with low-power layouts, it's wise to check the connectors with your power meter before looking.

Using a Power Meter for Power Measurement

When measuring fiber optic power with a power meter, attach the meter to the cable. Turn on the source of power (transmitter), and view the meter's measurement. Compare the meter measurement with the specified correct power for that particular system to be sure it doesn't have too much or too little power. The reason correct power measurement is so important with fiber optic cables is because the system works similar to electric circuit voltage, and the power must be just the right amount to work properly.

Testing Loss with a Power Meter

A power meter is used to test loss, but a test source is needed as well. The meter will measure the optical power that is lost in every part of the cable. The cable is mated with a working reference cable. Two methods used in loss testing are single-ended loss and double-ended loss. With single-ended loss testing, only the launch cable is used. With double-ended loss testing, a receive cable is also attached to the meter.

There are certain loss guidelines to follow for connectors, splices, multimode fibers, and singlemode fibers. You should understand these guidelines as well as the standard formula for calculating loss before getting started. Many training tutorial sites online provide these guidelines free of charge.

Other tools that may be required for the processes above include optical loss test kits, matching reference test cables, mating adapters with hybrids, a visual fault locator or fiber tracer, cleaning items, and an ODTR (for outdoor networks).

Fiber optic cables can be of great value to companies if they work properly. Use a fiber optic power meter and other useful tools to ensure that your fiber optic system will operate smoothly around the clock.

When using test instrumentation for fiber optic projects, many beginning technicians attempt to use the testing products without proper training or instruction. Since every manufacturer is different, the products each have their own set of instructions. Some can be used after carefully reading the manufacturer's manual while others require more detailed training and skill.

An OTDR (Optical Time Domain Reflectometer) is one testing instrument that poses problems when not used properly. Improper use or a failure to read the data correctly on this device can be very costly to companies and fiber optics specialists.

Uses of an OTDR

An OTDR can be used when installing an outdoor cable plant network in which splices are used between the cables. The OTDR will check the fibers and splices to be sure they are both good. The device sees the completed splice and confirms the splice's performance. Another use of an OTDR is to locate cable stress problems that are often caused when the cable is not handled properly during installation.

An OTDR can also be used in restorations once a cable has been cut. The instrument will locate the cut and help determine the quality of the splices, whether temporary or permanent. With singlemode fibers, an OTDR can be used to find bad connectors.

OTDR Limitations

An OTDR cannot be used to properly measure cable plant loss. The source and power meter should be used for this task because the OTDR is not equipped to show actual cable plant loss. When creating a fiber optics network in a building or LAN environment, an OTDR will likely not be sufficient for testing. It does not work well with short cables, and in these environments, fiber optic cables are usually much shorter than those used outdoors.

OTDR Expense

OTDRs can only be used in specific fiber optics environments and tend to be very expensive. So it's a good idea to determine if you will really need an OTDR before buying one. Fiber optics instrument rental companies usually offer these as rentals if you want to try it before buying or if you are working on a rare project in which an OTDR will be useful.

OTDR Measurements

One thing to remember about OTDRs is they measure the fiber, not the actual cable, in length. Since many manufacturers make the fiber longer than the cables that contain them to reduce fiber stress, the OTDR might show fiber where there is no cable. This could cause you to waste time digging for a cable where there are only fibers. Calculate the excess fiber into your measurements to avoid this problem.

With an OTDR, locating and correcting underground fiber optic problems can be easier. Just be sure to get proper instruction or training to ensure proper use of this helpful fiber optics instrument.

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