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Regarding safety in fiber optic installations, the first thing that comes to mind is usually eye damage from laser light in the fiber. People imagine a laser burning holes in metal or perhaps burning off warts. While these images may be real for their applications, they have little relevance to most fiber optic communications. Eye safety is an issue, but usually it’s not with light in the fiber.
Optical sources used in fiber optics, especially light-emitting diodes (LEDs) used in premises networks, are of much lower power levels than used for laser surgery or cutting materials. The light that exits an optical fiber is also spreading out in a cone, so the farther away from the end of the fiber your eye is, the lower the amount of power your eye receives. Some infrared light in fiber optic links is at wavelengths that cannot easily penetrate your eye because it’s absorbed by the water in your eyeball.
Still, it’s never a good idea to look into a fiber unless you know no source is being transmitted down it. Since the light is infrared, you can’t see it, especially if you are using a microscope, which can focus the light into your eye. Always check the fiber with a power meter before examining it.
The real eye safety issue is getting fiber scraps into the eye. During the termination and splicing process, you will be continually exposed to small scraps of bare fiber, cleaved off the ends of the fibers being terminated or spliced. If they get into your eyes, they are very hard to flush out and will probably require an emergency room visit. Whenever you are working with fiber, wear safety glasses!
Bare fiber safety
The broken ends and scraps of fiber created during termination and splicing are extremely sharp and can easily penetrate your skin. They invariably break off and are very hard to find and remove. Sometimes a pair of tweezers and a magnifying glass will get them out, but usually, you have to wait for them to infect and work themselves out.
When handling fibers, be careful not to stick the broken ends into your fingers. Dispose of all scraps properly. Some people keep a piece of double stick tape on the bench to stick fiber scraps onto. I prefer to use a dedicated container for all fiber scraps. In our training programs, we use the same deli-style, pint-size paper containers, with a lid. We put all the scraps into the container, then put on the lid, tape it and dispose of it later. Do not drop fiber scraps on the floor where they will stick in carpets or shoes and be carried elsewhere—like home!
Do not eat or drink anywhere near the work area. Fiber scraps can get into food or drink and be swallowed. The scraps can imbed themselves in you digestive system and never be found.
Fiber optic splicing and termination use various chemical cleaners and adhesives. Normal handling procedures for these substances should be observed. If you are uncertain of how to deal with them, ask the manufacturer for a materials safety data sheet. Always work in well-ventilated areas. Avoid skin contact and stop using chemicals that cause allergic reactions. Even simple isopropyl alcohol used as a cleaner is flammable.
Note that fusion splicers use an electric arc to make splices, so care must be taken to ensure no flammable gases are contained in the space where fusion splicing is done. Splicing is never done in manholes where gases can accumulate. The cables are brought up to the surface into a splicing trailer, which is temperature controlled and kept spotlessly clean.
Smoking should also not be allowed around fiber optic work, because ashes contribute to the dirt problems with fibers and increase the chance of explosions. This is because combustible substances are present.
You might be wondering what electrical safety has to do with fiber optics. Well, fiber cables are often installed around electrical cables. Electricians are well-trained in electrical safety, but some fiber optic installers are not. We’ve heard rumors of fiber installers being shocked when working around electrical cables and two fiber installers were killed when working on aerial cables.
They were installing all-dielectric self-supporting aerial cables on poles. The hangers, however, were metal and over 6 feet long. Both had attached the hangers to the poles, then when installing the fiber cables had rotated the hangers enough to contact high-voltage lines.
So even if the fiber is not conductive, fiber hardware can conduct electricity or the installer can come in contact with live electrical wires when working near AC power. EC
HAYES is the founder of Fotec, the fiber optic test equipment company and Cable U training. Find him at www.JimHayes.com.