General Operation Safety of Network System

Abstract

Work safety refers to the compliance of safety regulations in the production process. The purpose is to ensure the safety and health of individuals, as well as the normal and orderly production of enterprises, and to prevent casualties and property losses. Safety can never be trivial. The occurrence of safety accidents is always accompanied by heavy harm to individuals and their families, which also damages the operation and production of enterprises, and even drags the development of society and the country down in serious cases. Therefore, work safety is a critical policy in China, and also the primary consideration in pre-production.

Work safety refers to the compliance of safety regulations in the production process. The purpose is to ensure the safety and health of individuals, as well as the normal and orderly production of enterprises, and to prevent casualties and property losses. Safety can never be trivial . The occurrence of safety accidents is always accompanied by heavy harm to individuals and their families, which also damages the operation and production of enterprises, and even drags the development of society and the country down in serious cases. Therefore, work safety is a critical policy in China, and also the primary consideration in pre-production.

The safety in installation, operation and maintenance of network equipment are also covered in the scope of work safety. The operation of network equipment should comply with both the general rules of work safety and the safety rules specific to network equipment. This chapter will start with the introduction of general safety norms, including the safety awareness and operation safety knowledge required of operators, and then introduce the operation safety knowledge specific to network equipment, involving electrical safety, battery safety, radiation safety and other safety knowledge.

By the end of this chapter, you will

(1) Comprehend general safety norms (2) Grape the knowledge of electrical safety norms for network equipment operation (3) Grape the knowledge of battery safety norms for network equipment operation

(4) Grape the knowledge of radiation safety norms for network equipment operation (5) Grape other relevant knowledge of safety norm

1.1 General Safety Norms

The installation, operation and maintenance of network equipment must be carried out in accordance with certain rules and precautions, otherwise the equipment may be damaged to the point that it cannot work properly, or even cause personal casualties. In order to achieve work safety, the operator should first have safety awareness, and then master the corresponding knowledge of operation safety. For this purpose, this chapter will introduce the relevant knowledge.

1.1.1 Safety Awareness

Personnel involved in the construction, operation and maintenance of the network system should study and follow the Work Safety Law of the People’s Republic of China. They should adhere to the policy of “Safety First, Prevention First” and the awareness of “Safety Is of Paramount Importance”, and prevent and reduce the occurrence of engineering accidents and personal casualties by conscientiously learning the relevant operation safety knowledge and abiding by the relevant operation safety norms.

1.1.2 Operation Safety Knowledge

In the actual work and operation, safety is always the top priority, so the relevant norms must be strictly abided. The following is a general introduction to the necessary operation safety knowledge.

• 1. The personnel responsible for installation, operation and maintenance of the equipment must receive strict training, and should not take his/her post without corresponding qualifications for the post or comprehension of all safety precautions and correct operation methods.

• 2. During the installation, operation and maintenance of the equipment, the following requirements should be complied with in conjunction with the observance of local laws and regulations.

  • (a) Only qualified professionals and trained personnel are authorized to perform equipment installation, operation and maintenance.

  • (b) Only qualified professionals and trained personnel are authorized to remove safety facilities and repair equipment.

  • (c) Operators should promptly report to the responsible person any failure or error that may cause safety problems.

  • (d) The personnel who operate the equipment, including the operators, trained personnel and professionals, should have the special operation qualification required by the local authorities, such as the qualifications for high pressure operation, high altitude operation, special equipment operation qualification, etc.

• 3. The personnel operating the equipment should immediately terminate the operation once they detect the possibility of personal injury or equipment damage, and should report to the project leader, and take feasible and effective protective measures.

• 4. It is strictly prohibited to install, use and operate outdoor equipment (including but not limited to handling equipment, installing cabinets, installing cables, etc.) and connect the equipment to outdoor cables in bad weather such as thunder, rain, snow and strong wind.

• 5. It is strictly prohibited to wear watches, bracelets, rings, necklaces and other conductive objects when installing, operating and maintaining equipment.

• 6. During equipment installation, operation and maintenance, personnel operating the equipment must ensure that safety protection measures are in place, such as wearing insulating gloves, protective clothing, safety helmet and safety shoes, as shown in Fig. 1.1.

• 7. Installation, operation and maintenance must be carried out in accordance with the steps in the instructions in order.

• 8. Before the contact with any conductor surface or terminal, the shock hazard should be eliminated by measuring the voltage at the contact using a voltmeter.

• 9. All slots should be ensured to have a board or filler panel in place. The board should be prevent from dangerous voltage leakage,the normal air duct and control of electromagnetic interference should be ensured, and the backplanes, mother boards and boards should be kept free from dust and other foreign matters.

• 10. The user should carry out routine inspection and maintenance of the installed equipment according to the requirements of the instructions to ensure the timely replacement of the faulty parts and the safe operation of the equipment.

• 11. After the installation of the equipment, the packaging materials scattering in the equipment area should be removed, such as cartons, foam materials, plastic materials, binding straps, etc.

• 12. In case of fire, relevant personnel should press the fire alarm bell, and then evacuate the building or equipment area and call the fire alarm. In any case, never re-enter the burning building after evacuation.

Relevant concepts involved in the above introduction are explained as follows.

• 1. Professionals: Personnel who have the ability to train others or rich experience in operating equipment, while being clear about potential sources and levels of danger in the process of equipment installation, operation and maintenance.

• 2. Trained personnel: personnel who have received required technical training and accumulated necessary experience, are aware of the possible risks associated with a certain operation and are capable to take measures to minimize the risks to themselves and other personnel.

• 3. Users/Operators: All people other than trained personnel and professionals, including operators, customers, ordinary people who may come into contact with the equipment, etc.

Fig. 1.1

Safety protection measures

1.2 Operation Safety of Network Equipment

In view of the characteristics of network equipment, even technicians with general safety knowledge will inevitably encounter some specific operational problems during the installation, operation and maintenance of network equipment, including problems related to electrical safety, battery safety, radiation safety, mechanical safety and maintenance safety. Therefore, technical personnel need to master the detailed rules to ensure operation safety in any situation.

1.2.1 Electrical Safety

Electrical safety is a key to operation safety of network equipment system. In electrical operation , even a slightly improper operation may lead to casualties, equipment damage and other serious accidents, causing serious consequences. Therefore, the relevant electrical safety rules must be strictly observed during the equipment installation.

• 1. Grounding

  The so-called grounding includes working grounding and protective grounding. Working grounding refers to the grounding of the power supply neutral point (transformer or generator) of an electrical device, which functions as follows.

  • (a) To relieve the damage to electrical device insulation caused by the increase in the voltage to grounding of the two phases due to transient over-voltage or due to the other phase’s connection to ground in the electrical system.

  • (b) When the electrical device runs into a grounding fault, to provide a path for grounding fault current, in order to immediately start the protective device and cut off the fault circuit.

  Protective grounding refers to the grounding of the exposed current-carrying part of an electrical device, which functions as follows.

  • (a) To reduce the voltage to ground of the exposed conductive part in case of a grounding fault, that is, to reduce the contact voltage.

  • (b) To provide a path for grounding fault current, in order to immediately start the protective device and cut off the fault circuit.

  The network equipment should be installed, operated and maintained with guarantee that the protective ground wire is reliably grounded in accordance with the local power distribution norms for buildings. Installation of equipment to be grounded must begin with the installation of a permanently connected protective ground wire; for dismantling the equipment, the protective ground wire must be removed at the end. If the equipment employs a three-pin socket, you must ensure that the grounding terminal in the three-pin socket is connected to the protective ground wire.

• 2. Operation requirements for AC and DC power supply

  The supply voltage of a power supply system is classified as a hazardous voltage, which may lead to electric shock by direct contact or indirect contact through a wet object. Even, an improper or incorrect operation may cause accidents such as fire or electric shock. Such being the cases, the operation of a power supply system must comply with the relevant safety norms, including the following precautions.

  • (a) Before installing the equipment, confirm whether the upper-level equipment is matched with the over-current protection device.

  • (b) The equipment using a permanently connected power entry module should be externally equipped with an accessible disconnecting device.

  • (c) AC-powered equipment can be applied to TN and TT power supply system.

  • (d) For DC-powered equipment, it is necessary to ensure enhanced insulation or double insulation between DC power supply and AC power supply.

  • (e) If there is a possibility of touching a energized part during the electrical connection of the equipment, the corresponding breaking device for the upper-level equipment must be disconnected first.

  • (f) Before connecting a loaded (electrical equipment) cable or battery cable, it is necessary to confirm whether the input voltage is within the rated voltage range of the equipment.

  • (g) Before connecting a load (electrical equipment) cable or battery cable, it is necessary to confirm the polarities of the cable and terminal to prevent reversed connection.

  • (h) Ensure the correct electrical connection of the equipment before switching on the power.

  • (i) If the equipment receives multiple inputs, all inputs should be disconnected before operation.

• 3. Cabling requirements

  Proper cabling is beneficial to reduce the maintenance cost and prolong the service life of equipment. The following points need to be noted when cabling.

  • (a) In the case of making the power cable on site, the insulating cover of the power cable in other positions except the wiring part should not be cut, otherwise it may lead to short circuit, and then cause personal injury, fire or other accidents.

  • (b) The use in high temperature environment may cause aging or damage of the insulating cover of the cable. A sufficient distance should be kept between the cable and the power copper bar, current divider, fuse, heat sink and other heating devices.

  • (c) Signal cables and high-current or high-voltage cables should be bound separately.

  • (d) The cables provided by users should conform to local standards.

  • (e) No cable should pass through the air exhaust vent in the cabinet.

  • (f) The cables stored below zero temperature should be moved to and stored at room temperature for more than 24 h before laying or cabling.

• 4. TNV circuit

  A telecommunication network voltage (TNV) circuit is one that carries communication signals, which is defined as suitable for devices with restricted access areas. With proper design and protection, the voltage of this circuit will not exceed the specified limit under either normal operation or single fault. For TNV circuits, there are following general requirements.

  • (a) To avoid electric shock, never connect a safety extra-low voltage (SELV) circuit to a TNV circuit.

  • (b) In lightning weather, never plug or unplug the signal interface connected to the outdoor.

  • (c) To lower the fire risk, be sure to use 26 AWG telephone wires or bigger ones. AWG is short for American Wire Gauge, a standard for specifying wire diameters. The higher number before “AWG” refers to the thinner wire. Please refer to the corresponding manual for details.

• 5. Antistatic requirement

  When the human body moves, clothes rub, shoes rub against the floor, or you get an ordinary plastic product with your hands, the human body generates a static electric field that is prone to persist until discharge. Therefore, before touching a device or holding a plugboard or board, or an application specific integrated circuit (ASIC) chip with your hand, you must wear an ESD wrist strap, with the other end of it being well grounded, to prevent ESD-sensitive components from being damaged by static electricity on human body (see Fig. 1.2). At the same time, attention should be paid to the following two points.

  • (a) When holding a board, you must hold the edge area without a component, and never touch the chip by hand.

  • (b) A dismantled board must be packed with anti-static packaging materials before storage or transportation.

Fig. 1.2

How to wear an ESD wrist strap

1.2.2 Battery Safety

Batteries are commonly used in network equipment. The installation, operation and maintenance of the battery should meet the following requirements.

• 1. Never expose a battery to high temperatures or to heating devices, such as sunlight, heaters, microwaves, ovens and water heaters, as an overheating battery may explode.

• 2. To avoid battery leakage, overheating, fire or explosion, never disassemble or modify a battery, insert a foreign matter into it, or immerse it in water or other liquids.

• 3. In case of discoloration, deformation, abnormal heating or other anomalies happen to the battery in use or stored, it should be replaced immediately.

• 4. Before installing or maintaining a battery or performing other operations on the battery, you should wear goggles, rubber gloves and protective clothing to avoid the harm caused by electrolyte spills. If the battery leaks, avoid the leaked liquid from contact with skin or eyes. In case of contact, rinse the contact area with plenty of water immediately and go to the hospital for treatment.

• 5. When handling batteries, they should be placed in the required direction. Never turn the batteries upside down or tilt them.

• 6. In the installation, maintenance and other operations, the battery circuit should be kept disconnected.

• 7. A battery may only be replaced with one of the same type or equivalent type. Improper replacement may lead to battery explosion.

• 8. Never connect a metallic conductor with the battery poles or contact the battery ends, so as to avoid battery short circuit or body injury such as burns caused by battery overheating.

• 9. Disposal of batteries should comply with local laws and regulations, and it is not allowed to dispose them as household waste Improper disposal may lead to battery explosion.

• 10. Never squeeze or pierce a battery or make it fall, So as to avoid battery short circuit and overheating caused by the strong external pressure on it.

• 11. Damaged batteries should not be kept in service.

• 12. Prevent children or pets from swallowing and biting a battery, so as not to cause damage to them or cause battery explosion.

In view of the differences between batteries from different manufacturers, please read the instruction manual from the manufacturer before installing, operating and maintaining the battery. In addition, safety requirements differ for rechargeable and non-rechargeable batteries used in devices.

• 1. Safety requirements for rechargeable batteries

  Rechargeable batteries need to be protected against battery short circuits, flammable gases, battery leaks, and capacity loss.

  • (a) Protection against battery short circuit

    When the battery short-circuits, the instantaneous large current and the large amount of energy released may cause personal injury and property damage. Therefore, if possible, disconnect the working battery charging connection before performing the job, and avoid battery short circuit caused by conductive objects such as metal.

  • (b) Protection against flammable gases

    Lead-acid batteries will release flammable gases when working abnormally, so they should be placed where is ventilated, with fire prevention in place. Never use a lead-acid battery unsealed. Lead-acid batteries should be placed horizontally and fixed to ensure that hydrogen discharge measures are normal to avoid combustion or corrosion of equipment.

  • (c) Protection against battery leakage

    The battery may deform, damage or leak electrolyte at an excess temperature. When the battery temperature exceeds 60 °C, the electrolyte should be checked for leakage. Once electrolyte spills are discovered, possible damage from the electrolyte should be avoided when moving the leaky battery. Sodium bicarbonate (NaHCO₃) or sodium carbonate (Na₂CO₃) can be used for neutralizing and absorbing the spilled electrolyte.

  • (d) Protection against capacity loss

    After the battery connection is completed and before the power supply system is energized, the battery fuse or air switch should be confirmed to be disconnected, so as to avoid the battery capacity loss caused by long-term outage of the system as well as further damage to the battery.

    In addition to the above 4 requirements, it is also necessary to tighten the battery cable or copper bar by exerting the torque specified in the battery instructions, otherwise the virtual access of battery bolt may result in unaccessible connection voltage drop, or even heat the battery when the current is high to the extent of burning the battery.

• 2. Safety requirements for non-rechargeable batteries

  There are some safety requirements for devices that use dry batteries or non-rechargeable lithium batteries.

  • (a) For devices that use non-removable built-in batteries, the batteries should not be replaced by the user to avoid damage to the batteries themselves or the devices. If you need to replace the battery, you can find the manufacturer’s after-sales service personnel for replacement.

  • (b) In order to avoid battery burning and explosion, do not throw the battery into the fire.

1.2.3 Radiation Safety

Radiation here generally refers to electromagnetic radiation, that is, the emission of energy into a space from a source of radiation in the form of electromagnetic wave, or the transmission of energy within the space in this form. Electromagnetic radiation is divided into ionizing radiation and non-ionizing radiation. Electromagnetic waves with very short wavelengths or very high frequencies have great energy in each of its photons, which can break chemical bonds between molecules. This kind of radiation is called ionizing radiation, including gamma rays, cosmic rays and x-rays produced by radioactive materials. Electromagnetic waves with low frequency, whose photons can not damage the chemical bonds between molecules, are called non-ionizing radiation, such as visible light, laser, microwaves, radio waves, etc. The electromagnetic radiation studied here refers to non-ionizing radiation. Electromagnetic radiation is almost everywhere in our daily life. The electromagnetic radiation that is restrained within certain energy limit does not exert impact on people’s health until the energy exceeds the limit to gradually produce some negative effects. Next is some safety knowledge of electromagnetic radiation.

• 1. Electromagnetic field (EMF) exposure

  For wireless transmitting equipment, equipment with wireless transmitting function, and high voltage equipment and facilities, hazards exposure to their power frequency EMF should not be ignored. The operator must comply with relevant local laws and regulations when erecting some specialized equipment or facilities. Any changes to equipment structures or antennas, or RF output specifications or parameters, or to the site environment of specialized erection equipment or facilities will require reassessment of EMF exposure.

  • (a) EMF exposure zone

    An EMF exposure zone (over-limited zone) refers to an area that is at a certain distance from electromagnetic equipment or facilities. The forbidden zone is designated according to the exposure limits prescribed by relevant regulations for the purpose of controlling the exposure of the public or operators to the EMF. Appropriate measures to ensure a safe distance from EMF exposure include but are not limited to the following.

    • (i) Sites where specialized equipment or facilities are deployed should not be open to the public and should be planned in areas inaccessible to the public.

    • (ii) Only professionals and trained personnel should be allowed to enter the site of specialized equipment or facilities.

    • (iii) Before entering the forbidden zone of EMF exposure, professionals should know the location of the areas of excess radiation in advance, and close the emission source before entering.

    • (iv) The site should be clearly marked to alert professionals that they are or may be in the EMF exposure zone.

    • (v) After the installation in the site, it should be monitored and checked regularly.

    • (vi) Effective physical barriers and striking warning signs should be set up in each EMF exposure zone.

    • (vii) Isolating devices should be installed in the outside of the equipment structure.

  • (b) Security precautions for installation and use of BTS

    The RF electromagnetic radiation of Base Transceiver Station (BTS) is reasonably designed to be below the limits of relevant standards. Therefore, the BTS under normal working conditions will not endanger the public or relevant personnel. However, some defective BTS antennas or other defects in the BTS may cause the RF electromagnetic radiation to exceed the limits.

    Professionals should keep to the following principles when installing and operating the BTS or its antennas.

    • (i) Read the Work Safety Proposal before installing and operating the BTS or its antenna and comply with local laws and regulations.

    • (ii) Before installing or maintaining an antenna near a tower, mast, etc. where a BTS and its antennas are installed, request the relevant personnel to turn off the antenna transmission source.

    • (iii) When necessary, field operators should wear radiation monitoring and alarm instruments.

    • (iv) Raise the antenna mounted on the roof to exceed the height of persons who may work and live on the roof.

    • (v) The transmitting antennas installed on the roof should be far away from areas where people are most likely to tread, such as roof access points, telephone service points and heating, ventilation and air conditioning equipment.

    • (vi) The directional antenna installed on the roof should be placed outside, without facing the building.

    • (vii) Try to balance the choice between large- and small-aperture antennas, as the former provide better signal coverage, while the latter is able to reduce visual impact.

    • (viii) Be prudent to install antennas provided by multiple companies in the same place. It may be a good idea for a community or building management organization to install antennas provided by all companies in the same location, but this is prone to safety risks, so installation personnel should be very careful.

    • (ix) Special security measures should be put in place at antenna stations near hospitals and schools.

  • (c) Guidance for the use of other wireless equipment

    • (i) The safe distance from EMF exposure specified in the relevant manuals of wireless equipment shall be followed, if any.

    • (ii) If the RF emission power of some equipment is low enough to meet the safety requirements for EMF exposure, there is no need to limit the service distance.

    • (iii) For some equipment specially designed to meet the safety requirements for EMF exposure at the time of operating close to the human body, there is no need to limit the service distance.

  • (d) Guidance for the use of high-voltage equipment or facilities

    Only the power frequency EMF generated by equipment or facilities with higher voltage (for example, more than 100 kV) will have adverse effects on human body, so it is necessary to conduct EMF exposure assessment according to relevant requirements.

• 2. Laser radiation

  Laser is also widely used in today’s social production and life. Laser transceivers are often configured in network equipment, which are mainly used in optical fiber transmission systems and related test tools. Infrared lasers are used to provide the light for optical fiber communications systems, thus optical fibers or connector ports emit lasers that are invisible to the naked eyes but have very high power density. Therefore, looking at the laser output terminal with naked eyes will burn your eyes. In order to avoid damage caused by laser radiation, the following operation rules should be observed when laser related operations are carried out.

  • (a) Non-authorized personnel who have received relevant training shall not carry out relevant operations.

  • (b) Always wear goggles properly in laser or optical fiber related operations.

  • (c) Make sure to turn off the light source before disconnecting the fiber optic connector.

  • (d) After disconnecting the optical fiber connectors, install the optical fiber caps to protect all the optical fiber connectors.

  • (e) Before making sure that the light source has been closed, never gaze at the bare optical fiber or connector terminal with naked eyes, but immediately install a dust cap for the optical fiber connector.

  • (f) Ensure that the optical fiber is disconnected with the light source before cutting or welding the fiber.

  • (g) Use an optical power meter to measure the optical power to ensure that the light source is turned off.

  • (h) Take care to avoid laser radiation when opening the front door of the optical fiber transmission system.

  • (i) It is strictly prohibited to use optical instruments such as microscopes, magnifying glasses and loupes to watch optical fiber connectors or optical fiber terminals.

1.2.4 Other Safety Knowledge

Operational safety knowledge not only covers the aspects introduced above. Other safety knowledge such as mechanical safety, maintenance safety and safety signs will be introduced below.

• 1. Mechanical safety

  • (a) Safety in lifting installation

    Lifting installation shall meet the following requirements.

    • (i) Personnel carrying out lifting installation must receive relevant training and get qualified for the operations before the taking up the post.

    • (ii) Lifting apparatuses must be all in readiness and be verified before use.

    • (iii) The lifting apparatuses must be firmly fixed on load-bearing fixtures or walls before lifting operations.

    • (iv) During the lifting, the included angle between the two cables should not exceed 90°, as shown in Fig. 1.3.

  • (b) Safety with ladders

    The following requirements should be satisfied before using the ladder.

    • (i) First confirm that the ladder is intact, and then check that it is in line with the load-bearing restrictions stipulated for the ladder. Overweight use is strictly prohibited.

    • (ii) The slope of the ladder is best set to 75°, which can be measured with an angle square. When using a ladder, the wider ladder butt should be adown or the ladder bottom should be protected against slipping. The ladder should be placed in a stable place.

    The following requirements should be satisfied during using the ladder.

    • (i) Do not deviate the center of your body weight from the edge of the ladder.

    • (ii) Keep your body steady before operation to reduce risks and ensure safety.

    • (iii) Do not climb above the fourth step from the top of the ladder

    • (iv) If you need to climb the roof, the vertical height of the ladder above the eaves should reach at least 1 meter.

  • (c) Safety in drilling

    Drilling on the cabinet is strictly prohibited. Drilling operations that fail to meet the requirements will damage the electromagnetic shielding performance of the cabinet or damage the cables inside. The metal filings produced by drilling, if any, will cause short circuit to the circuit board if they swoop in the cabinet. The following requirements shall be satisfied when drilling on the wall or ground.

    • (i) Always wear goggles and protective gloves when drilling.

    • (ii) During drilling, the equipment should be shielded from the metal filings swooping in. After drilling, the metal filings should be cleared up in time.

  • (d) Safety in heavy load handling

    • (i) Before handling heavy objects, get ready for load bearing to avoid the operation personnel being crushed by heavy objects. When handling a shelf, keep your back straight and move steadily to avoid sprain.

    • (ii) Wear protective gloves when handling equipment by hand, so as not to cut your hands by sharp corners.

    • (iii) When handling a shelf, hold the handles or the bottom edge of the shelf, instead of the handles of the installed modules (e.g. power module, fan module and board) in it.

• 2. Maintenance safety

  The following requirements are generally required for maintenance on equipment.

  • (a) When replacing any accessories or components in the equipment, wear the ESD wrist strap, and ensure that one end of the wrist strap is well grounded, and the other end is in good contact with the your skin.

  • (b) When replacing parts, properly place the parts, screws, tools and other objects, so as to prevent them from falling into the running fan and damaging the fan or equipment.

  • (c) When pulling out the shelf or parts to be replaced from the cabinet, pay attention not to be crushed or smashed by the unstable or heavy equipment installed in the cabinet.

  Here are a few things need to be noticed in maintenance.

  • (a) Replacement of replaceable fuse

    • (i) To replace the fuse, the fuse with the same specification as the original one should be selected for the replacement.

    • (ii) Before replacing the fuse at the panel, be sure to disconnect the power supply of the equipment, otherwise there may be electric shock hazard.

    • (iii) The replaceable fuse is generally located at the panel near the input or output port of the AC or DC power supply for the equipment.

    • (iv) To determine the specification of the fuse for replacement, refer to the specification of the backup fuse, or the specification of the standard fuse on the panel. A non-conforming fuse may result in equipment damage, personal injury or property damage.

  • (b) Replacement of soldered fuse

    • (i) For the fuse with screen-printed rating on the board, it should be replaced only by authorized personnel according to the screen-printed rating.

    • (ii) For the fuse without screen-printed rating on the board, it must be returned to the factory for repair, instead of being maintained on site. If replacement is needed, it shall be replaced only by authorized personnel according to the model and rating provided by the manufacturer for the corresponding item number in the Bill of Material of the product.

  • (c) Replacement of distribution box and board

    • (i) Before replacing the distribution box, ensure that the front protective air switch is disconnected, and wear insulating gloves properly.

    • (ii) When replacing the board, never contact the components on the board directly by hand, so as not to damage the board.

    • (iii) The unoccupied slot should be installed with a filler panel.

  • (d) Replacement of fan

    When replacing the fan, wait until the fan stops completely and pull out part of the fan by palling the handle on the fan module. Then, pull the entire fan module out of the frame, otherwise the blades may injure your fingers.

• 3. Description of safety signs

  • (a) Signs of laser hazard classes

    Laser danger level signs are shown in Figs. 1.4 and 1.5. When optical fiber related operations are carried out, it is strictly prohibited to approach or look at the optical fiber outlet with naked eyes. For other considerations for laser-related operations, please refer to Sect. 1.2.3.

  • (b) Signs of equipment weight

    Equipment weight signs is shown in Fig. 1.6. Figure 1.6 (1) indicates that the weight of replaceable/pluggable part or equipment exceeds 18 kg, that it needs to be lifted by two people jointly; Fig. 1.6 (2) indicates that the replaceable/pluggable parts or equipment weigh more than 32 kg and need to be lifted by three people; Fig. 1.6 (3) indicates that the part or equipment weighs more than 55 kg and needs to be moved by a forklift or by four people.

  • (c) Sign of regular cleaning of dustproof net

    The sign of periodic cleaning of dustproof net is shown in Fig. 1.7, indicating that the dustproof net should be cleaned and replaced periodically.

  • (d) Warning sign of interlocking device

    In general, the door of outdoor equipment is fixed by a metal rod after opening to prevent accidental closing of the door. To close the door, you should lift the support rod. The warning sign of the interlocking device is shown in Fig. 1.8, indicating that the metal rod supporting the door should be lifted before closing the door.

  • (e) Danger sign of high voltage

    Danger sign of high voltage is shown in Fig. 1.9. When this sign is displayed, please read the safety manual completely before operation to ensure that you have understood the precautions in the manual.

Fig. 1.3

Lifting a heavy load

Fig. 1.4

Signs for Laser Hazard Class 1

Fig. 1.5

Signs for Laser Hazard Class 1 M

Fig. 1.6

Signs of equipment weight

Fig. 1.7

Sign of periodic cleaning of dustproof net

Fig. 1.8

Warning sign of interlocking device

Fig. 1.9

Danger sign of high voltage

1.3 Summary

This chapter starts with the introduction of general safety norms, including the safety awareness and operation safety knowledge required of operators, and then introduce the operation safety knowledge specific to network equipment, involving electrical safety, battery safety, radiation safety and other safety knowledge.

Upon the study of this chapter, the reader should master the general safety norms and operation safety knowledge.

1.4 Exercise

• 1. During the lifting, the included angle between the two cables should ().

  • A. <60°

  • B. <90°

  • C. >60°

  • D. >90°

• 2. Among the following statements about electrical cabling, the false one is ().

  • A. Signal cables and high-current or high-voltage cables should be bound together for space saving.

  • B. The cables provided by users should conform to local standards.

  • C. No cable should pass through the air exhaust vent in the cabinet.

  • D. The cables stored below zero temperature should be moved to and stored at room temperature for more than 24 h before laying or cabling.

• 3. Among the following statements about laser-related operations, the false one is ().

  • A. Non-authorized personnel who have received relevant training shall not carry out relevant operations.

  • B. Always wear goggles properly in laser or optical fiber related operations.

  • C. Make sure to turn off the light source before disconnecting the fiber optic connector.

  • D. It is recommended to use optical instruments such as microscopes and magnifying glasses to watch optical fiber connectors or optical fiber terminals for a close-up view.

• 4. [Multi-choice] It is strictly prohibited to () in bad weather such as thunder, rain, snow and strong wind.

  • A. Install, use and operate outdoor equipment

  • B. Connect the equipment to outdoor cables

  • C. Install, use and operate indoor equipment

  • D. Conduct indoor operations

• 5. [Multi-choice] Among the following statements about operations related to rechargeable batteries, the correct ones are ().

  • A. Short circuits should be avoided.

  • B. Sodium bicarbonate can be used for neutralizing and absorbing the spilled electrolyte.

  • C. The batteries can be turned upside down during handling.

  • D. In the installation and maintenance, the battery circuit should be kept disconnected.