Ch01 e

Notas del editor

• #4: The quality of the service provided by the cabling is directly related to the quality of the installation. This course prepares the student for an entry-level position in the cabling industry and the BICSI Installer, Level 1 exam. The Installer, Level 1 exam is designed for individuals with little or no prior work experience in voice, data, or video telecommunications cabling installation. Starting with the first wired network, this chapter discusses the evolution of cabling to the present day and for the future. In addition, the skills and tasks associated with most positions in the cabling industry are discussed. Among the topics covered are the organizations responsible for establishing and maintaining safety codes and standards, safety around electricity, lab and workplace safety practice, and personal safety equipment. All installers are expected to follow the practices and guidelines outlined in this chapter.
• #5: When a person speaks into the phone, the vibrations are converted into an analog signal which is then sent down the telephone cable. When the signal reaches the local telephone office, it is strengthened and sent to another telephone office along the route to the destination. When it reaches the earpiece of the other person, the analog signal is translated into vibrations that replicate the caller's voice and words. 
• #6: When a person speaks into the phone, the vibrations are converted into an analog signal which is then sent down the telephone cable. When the signal reaches the local telephone office, it is strengthened and sent to another telephone office along the route to the destination. When it reaches the earpiece of the other person, the analog signal is translated into vibrations that replicate the caller's voice and words. 
• #7: Modern telcos use digital devices called switches to connect calls. When dialing a telephone number, a switch connects the caller to the cable of the destination phone or to another telco if the person is not local. The idea of grouping users and resources most likely to communicate with each other reduces traffic on the rest of the network. Computer networking owes a tremendous debt to the telephone pioneers who prepared the way for it. Those who design computer networks have recently faced the same problem, almost a hundred years after it was encountered in telephony. The idea of grouping users and resources most likely to communicate with each other reduces traffic on the rest of the network.
• #8: Another important trend to watch for is integrated wiring , that is, all signals traveling on the same type of cable. Installers who are aware of these advancing technologies will be likely to employ future technologies in their upgrades and expansion.
• #9: A network that cuts corners by using lower grade cabling, inexperienced installers, or does not conform to standards, will cost the customer more in the end when users complain about slow speed or connection problems.
• #10: A cable installer's job requires several skills. First the installer pulls cabling through buildings and homes. After the cables are in their proper place and secured, the installer terminates them with the appropriate connectors or secures them to a punch down block. The installer next tests the cables to see if they are wired correctly and are run to the correct workstations. The installer may also participate in certifying the cables. This involves generating performance documents based on test data. These documents can be used later if problems develop, and they can guide plans for network expansion and change. There are several options after working as a technician for a few years. Many technicians will work to become supervisors or project managers. Others may wish to learn more about networking and networking equipment, moving on to becoming a network designer or engineer. Others enjoy working with customers and go into sales of network installation services.
• #11: Electricians generally specialize in wiring alternating current (AC) power systems, but some may be found installing computer wiring and equipment, telephone wiring, or fiber-optic cables. Consult local and state offices to check these regulations.  Most licensed electricians are authorized to install communications cables. Not all are trained to do so and not all are competent to do so. Communications cabling is a specialized field requiring extensive training to become a professional. This course provides the skills to install cables and their termination systems. Proficiency comes from experienced gained on the job.
• #12: The successful installer should plan on periodically updating their job skills and learning more about the industry or related industries through continuing education. Often, industry certification and time in the trade can waive certain higher-education requirements. Consult with a local school for more information about their requirements and opportunities.
• #13: All installers and companies must adhere to the safety standards and codes of conduct that apply to them. Consult local and state building codes that may require special installation techniques or safety equipment.
• #14: NIOSH is part of the Centers for Disease Control and Prevention (CDC). The Occupational Safety and Health Act legislation of 1971 led to the creation of this agency charged with job and worker safety. OSHA's mission is to ensure safe and healthful workplaces. OSHA inspectors have the power to impose heavy fines and/or shut down a jobsite should they find serious safety violations. Anyone who works on, or is responsible for, a construction site or business facility needs to be familiar with OSHA regulations. The organization offers safety information, statistics, and publications on its website.
• #15: The UL focuses on safety standards, but has expanded its certification program to evaluate twisted-pair LAN cables for performance. Listing by UL denotes initial testing and periodic retesting to assure continuing conformance to standards. UL tests and evaluates samples of cable, and then, after granting a UL listing, the organization conducts follow-up tests and inspections. This independent testing and follow-through make the UL markings valuable symbols to buyers. In general terms, the NEC concerns itself with how a cable burns-how hot it must get to catch fire, how long it will burn once it does catch fire, and what kinds of gasses it gives off as it burns. NEC type codes are listed in catalogs of cables and supplies. These codes classify specific categories of products for specific uses . The differences between these markings concern the amount of electrical power that could run through the cable in the worst case.
• #16: It is important for cable installers to be aware of these environmental safety agencies, because job sites are often sources of violations. Acts such as tossing out a jar half filled with cleaning solvent can be criminal and result in large fines. Be aware of the environmental protection laws that apply to any project. Local, state, or national codes are designed to protect individuals who will occupy the building after construction or cable installation. Cable installers who work in countries other than the United States must be knowledgeable of the local and international safety codes and standards, and follow them.
• #17: Since there are many hazards when installing cable, the installer should be prepared for all situations so that accidents or injuries can be prevented.
• #18: Do not become complacent to the hazards of high-voltage wiring nearby just because most of the work is dealing with low-voltage. Cable installers must learn how to detect unsafe voltages that appear where they should not be, and how to deal with them safely until a trained electrician arrives.
• #19: Electricity can cause serious injury and even death. Most of the cables installed by the cabling technician will carry only low, signaling voltages, but most of these cables travel near wires carrying much higher voltages. Similarly, the network devices that will be installed may not use high-voltage to process signals, but they are connected to power mains all the same, and failures can happen. Hazardous voltages are more likely to exist in the buildings and businesses where the cabling installer works, because these work areas are often in unfinished spaces and access areas.
• #20: Lightning protectors must be installed in compliance with local telephone company requirements and applicable codes. Telephone wire pairs should not be used without authorization. If authorization is obtained, do not remove or modify telephone circuit protectors or grounding wires.
• #21: Using a known reliable voltage measurement device such as a multimeter or voltage detector, take measurements immediately before starting work. Measure again whenever work is resumed the following day or after a break on any job (because someone may have made changes), and then check again when finishe d
• #22: Grounding works by providing a direct path to the earth for any voltages that come in contact with it. Grounding equipment conducts any stray voltage to the earth without hurting that equipment. Without a proper path to ground, stray voltages may use another path to the ground, such as a person's body. Be aware of the grounding system in the lab and on each job site. It should be verified that the grounding system actually works. It is not uncommon to find that grounding was improperly done or was never installed in the first place
• #23: By connecting the third wire in the electric outlet to ground, any voltages that develop should pass to ground. Whenever an electrical current takes this path, it causes protective devices such as circuit breakers and GFCIs to activate, or trip. By interrupting the circuit, circuit breakers and GFCIs stop the flow of electrons, and reduce the hazard of electrical shock and fire A breaker works by sampling the current that is traveling in the circuit, and trips when the current exceeds a certain value. GFCIs are used in areas that could be exposed to moisture and humidity. A GFCI works by comparing the amount of electrical current coming into a circuit (on the black wire) with the amount leaving (on the neutral or red wire). if more current enters the circuit through phase wire than leaves through neutral wire, there is a current leak or ground fault.
• #24: The terms bonding and grounding are often erroneously used interchangeably. Grounding is providing the actual connection to the building ground or the electric company neutral conductor. Bonding is interconnecting various devices that may require grounding and providing the connection to the grounding conductor.
• #25: Bonding involves providing a means for various wiring fixtures to interconnect with the grounding system. It may be thought of as an extension of ground wiring. A device like a switch or router may have a bonding strap between its case and a ground circuit to ensure a good connection. It makes good sense to install grounding straps and devices when supplied with equipment. The few minutes it takes to install them can prevent a serious injury or the loss of valuable equipment.
• #26: In order that there may be some commonality in grounding systems, several national standards have been formulated. The National Electrical Code (NEC) written by the National Fire Protection Association (NFPA) sets the minimum safety requirements for any electrical wiring and grounding. "Commercial Building Grounding and Bonding Requirements for Telecommunications", also known as TIA/EIA-607 (Telecommunications Industry Association/ Electronics Industry Alliance), supports a multi-vendor, multi-product environment, as well as the grounding practices for various systems that may be installed on customer premises. TIA/EIA-607 specifies the exact interface points between a building's grounding system and the telecommunication/equipment grounding configuration. It also specifies that the building's grounding configurations needed to support this equipment. After the network is properly bonded and grounded, pay particular attention to how close telephone and network wiring is laid from high-voltage wiring, lightning grounding wire, and grounding rods. Separation of these types of wires is important.
• #27: Another reason for the separation of wires is to minimize the possibility of accidental contact with the hazardous voltages. Never install cabling near bare power wires, lightning rods, antennas, transformers, hot water pipes, or heating ducts. Never place data or telephone wire in any conduit, box, channel, duct, or other enclosure containing power or lighting circuits, unless the duct or channel has special dividers to prevent these wires from coming together and to provide electromagnetic shielding. Furthermore, never bundle or tie data cables with power cables or extension cords. Not only should wires be separated when working near electricity but care must be taken not to damage electrical wires when cutting or drilling holes in walls or floors.
• #28: If the spark of an ESD discharge can be felt, it is already many times greater than that required to destroy some electronic components.
• #29: Steps must be taken to deal with ESD in order to protect sensitive electronic equipment. It is far better to prevent static than to cope with it. Personal grounding devices like wrist straps are not required while cabling and terminating circuits. However, they should be worn any time when installing, inspecting, upgrading, or changing modules in a device.
• #30: The workspace shown depicts many common elements needed when working with sensitive electronic equipment. All of these devices interconnect to ensure that each element of the work area, the device, and the technician are all at the same electrical potential at all times. This is the best defense against ESD. If all elements are at the same potential, there is no excess of electrical current that can jump a gap and damage equipment. Set computer equipment on ESD protective work surfaces Place an ESD protective mat beneath the chair of a computer user. These absorb ESD. Temperature and humidity also play a role in ESD. Cooler and drier environments are especially prone to ESD, so consider using a humidifier.
• #31: Not only is it important to be safe when working around electricity, the cabling technician must also be familiar with other potential hazards on the job. The workplace should be a safe environment whether it is in the classroom lab or on the job site.
• #32: When routing cable through spaces where air is circulated, such as a plenum, use a fire-rated cable. The plenum area can be distinguished from a non-plenum area because it will not have air return ducts running through the space. The entire plenum area is the return path of air to the HVAC (Heating, Ventilation, and Air Conditioning) system Always find out in advance what the local codes are. Some building codes may prohibit drilling or cutting holes in certain areas such as firewalls or ceilings. The site administrator or facility engineer will be able to help determine which areas are off limits.
• #33: The manager of the company should identify if there are other hazards. In some cases, the use of non-sparking tools may be required to prevent an explosion. Other environments may require the use of a dust-filtering mask, or require that employees have a portable gas mask in case poisonous fumes are released. In some cases OSHA may require specialized safety training prior to working in hazardous environments It might not make sense to take every job. There may be a serious risk of being hurt, contaminated, or killed. Consider the risks of each job before committing to it. A particular hazard is maintenance holes or other confined spaces. These are areas which provide access to underground cables. Gasses such as carbon monoxide or methane often accumulate in these places. This displaces oxygen, creating an invisible, lethal hazard. Never enter such spaces without training, and avoid going in alone. If you encounter such gasses, you will need someone to pull you out or at least summon help.
• #34: Regardless of the type or construction, be sure the ladder has a label certifying that it complies with specifications of the American National Standards Institute (ANSI) and that Underwriters Laboratories (UL) lists it as passing its standards Be sure that the ladder is long enough to work from comfortably and sturdy enough to withstand repeated use. Fiberglass ladders are most commonly used in cable installation. Although aluminum ladders are lighter, they are less stable and should never be used around electricity. When working near electricity, only dry wood or fiberglass ladders should be used. Each time a ladder is used, inspect it for loose or damaged rungs, steps, rails or braces. Make certain the spreaders on stepladders can be locked in place and that the ladder has safety feet which will provide more stability and reduce the chances of the ladder slipping while working. Never use a ladder that is defective. Stepladders should be fully opened with the hinges locked. Straight ladders should be placed at a four-to-one ratio. This means the base of the ladder should be 0.25 m (10 in.) away from the wall or other vertical surface for every 1 m (3 ft) of height to the point of support Always face the ladder and hold on with both hands. Hold onto the ladder with one hand at all times. To maintain balance on the ladder when working, a good rule is to keep the belt buckle between the ladder rails. Make certain that no one could bump into the ladder. If the ladder must be set in a traffic area, use a barricade or have another coworker guard the ladder. Cordon off the work area with appropriate markers like traffic cones or caution tape.
• #35: No food or beverages in the work area should be allowed. If fiber particles are ingested, they can cause serious internal bleeding. And they are virtually invisible to most medical detection technologies. Do not look directly into the end of fiber cables Always keep a first aid kit nearby.
• #36: Many agencies provide industrial safety and first aid training (often called First Responder) from beginning levels through emergency medical technician ratings. Find out which agencies offer such training locally. In addition, many companies encourage employees to obtain such training at company expense or with tuition assistance.
• #37: Proceed to the nearest exit and help others to the exit. If there is smoke in the corridors, crawl to the exit since smoke rises. Call the emergency services number and tell them where the fire is, what type of fire is burning, the size of the fire, and if people are still in the building. If someone catches on fire, remember the tip, "Stop, Drop, and Roll". Stop, do not run. Drop to the floor. Roll on the floor to extinguish the flames. Should there be a need, a nearby safety shower, fire blanket, hose, fire extinguisher, or anything else that smothers the flame could be used.
• #38: Before fighting the fire, make sure that there is an escape route if the fire cannot be extinguished. Always fight the fire with one's back to the exit. Never let the fire cut off the escape route. Fire extinguishers have labels that identify which kinds of fires they are designed to fight. In the United States, these are called ratings. For example, a fire extinguisher with the rating "A:B:C" can fight Class A, B and C fires. Four different types of fires have been classified in the United States
• #39: Injury prevention is everyone's responsibility. Keep alert to situations that could result in an injury. Developing and using safe work practices is by far the best method for preventing injuries in the workplace.
• #40: Eyes are much easier to protect than to repair, so safety glasses should be worn when cutting, drilling, sawing, or working in a crawl space If chemicals come in contact with the eyes, flush them with running water for at least fifteen minutes using the emergency eye wash cup. If pain continues, seek medical attention immediately. Wear shoes appropriate for the job. Sturdy, fully enclosed shoes should be worn. They should be able to protect the soles of the feet from sharp objects on the floor.