Working with and around electricity poses hazards that most people don’t face in their daily jobs. From apprenticeship training throughout their careers, safety training is a continual process for electricians. Working with low voltages carried by copper in structured wiring systems is perceived as less dangerous than higher voltages, and fiber optic cable carries no electricity, yet both require attention to safe work practices.
Much of the cable for building security, alarm and control systems remains copper, but fiber optic cable segments are a part of a growing number of buildings’ structured wiring.
“I do not foresee any change in the cabling for building security, alarm and control systems for installing copper and coaxial cable for systems under 1,000 feet,” said James Dallas, training manager, Kitco Fiber Optics, Virginia Beach, Va. “For security systems that cover larger areas, it makes sense to convert those systems to fiber. The fiber in this scenario carries data at much greater distances with very little signal loss and does not require amplifiers or signal regenerators.”
The data in fiber is much cleaner, and there is much less of a chance of false alarms.
“The fiber is tamper-proof,” Dallas said. “A fiber optic signal can’t be tapped into by clipping onto the fiber like it can be with copper. Any disruption to the fiber by an intruder will cause a loss of signal, and you can pinpoint the exact area of intrusion using an OTDR [optical time-domain reflectometer].These fiber topologies are not difficult to install, but they do require a different skill set and have different installation requirements, cable-bend diameters and special tools. Persons installing these fiber topologies should be certified fiber optic installers and/or technicians.”
Even though fiber itself poses no electrical hazard, there are safety procedures to be followed. Doug Swalec, senior staff applications engineer for research and development, Panduit, Tinley Park, Ill., said that those hazards actually include the tools used to prepare the fiber.
[SB]“When prepping fiber cable, sharp objects such as a cable knife will be used,” Swalec said. “Armored cabling has a thin but very sharp layer of armoring, and Kevlar gloves should be worn to prevent cuts to hands. Safety glasses also should be used. When cleaving or scoring fiber, small lengths of bare glass will be created; to prevent injury, these need to be disposed of properly into a hazardous waste container.
“When working with live fiber systems, transmitters are disabled on the individual fiber or fibers being maintained in order to prevent eye injuries. Kevlar gloves and approved disposal containers should be used. During the maintenance of the fiber system, absolutely do not look into or direct fiber into areas of the eye or look at a fiber end-face when the transceiver is not turned off.”
Several characteristics contribute to the view that fiber is safe to work with, including the fact it is lightweight and small.
“Because fiber is made from glass and glass is a dielectric, it does not carry electricity,” Dallas said. “Another fiber feature is it does not attract lightning. Glass is also immune to electromagnetic interference and radio frequency interference. These characteristics permit the installer to have less restrictions when installing fiber optic cabling, and the cabling can be run through hazardous areas where copper cabling cannot be installed.”
Even so, Dallas said safety is a critical element in training fiber optic technicians.
“We are adamant about safety in all of our fiber optic classes,” he said. “We have lectures dedicated to the safety aspects of working with fiber and laser lighting. Safety is reinforced every time we go into the lab and begin working with fiber. No food or drinks are permitted in the classroom when working on fiber.
“What installers must be cautious about is the optical energy emitted from LEDs or lasers. These light sources operate in the near-infrared and infrared wavelengths and are not visible to the eye. Because the fiber is so small, the installation technician uses a 100x, 200x or a 400x microscope to view the end-face of the fiber for cleanliness or damage.
“It is a must that you ensure the light source is turned off or the fiber is removed from the source before inspecting the end-face of the fiber. If not, injury from the laser’s infrared wavelengths output can cause cataracts and corneal and retinal burns. This damage will occur before a technician becomes aware of it. The lasers used in these systems are Class 1 lasers and are considered safe to the naked eye, but they become a serious hazard when inspecting the fiber using a microscope as the output from the fiber is focused directly into your eye,” Dallas said.
For more information on the four classifications of lasers, see the Center for Devices and Radiological Health and IEC Publication 825 and ANSI Z136.2 for full technical definition and preventive measures.
“Other light sources commonly used when working with fiber are Class II or Class III laser light sources, which are in the visible spectrum,” Dallas said. “These sources are used with a continuity tester to confirm the fiber will pass light from one end to another. These laser light sources are hazardous to the naked eye and cause damage or partial blinding are removed, even if they are focused on the eye for a split second.”
The other hazard to the fiber installer occurs when the protective buffer and acrylate coating are removed from the fiber and the installer is working with bare glass.
“The acrylate coating and fiber protect the glass and permit the glass to be very flexible. Once those items are removed, the glass becomes very stiff and easy to break. The glass can easily splinter and pierce the skin and an eye. The glass is also very small, 125 µm in diameter, and it is hard to see. Never have food out or beverages in the area where fiber is being terminated. We all need fiber in our diet, but this is definitely the wrong fiber,” Dallas said.