Safe Lab Procedures (2.1)
Everyone must understand and follow safety procedures.
Procedures to Protect People (2.1.1)
Safe working conditions help prevent injury to people and damage to computer equipment. A safe workspace is clean, organized, and properly lit.
General Safety (220.127.116.11)
Follow safety guidelines to prevent cuts, burns, electrical shock, and damage to eyesight. As a best practice, make sure that a fire extinguisher and first-aid kit are available. Poorly placed or unsecured cables can cause tripping hazards in a network installation. Cable management techniques such as installation of cables in conduit or cable trays help to prevent hazards.
This is a partial list of basic safety precautions to use when working on a computer:
Remove your watch and jewelry and secure loose clothing.
Turn off the power and unplug equipment before performing service.
Cover sharp edges inside the computer case with tape.
Never open a power supply or a monitor with a built-in power supply.
Do not touch areas in printers that are hot or that use high voltage.
Know where the fire extinguisher is located and how to use it.
Keep food and drinks out of your workspace.
Keep your workspace clean and free of clutter.
Bend your knees when lifting heavy objects to avoid injuring your back.
Wear safety goggles to prevent damage to eyesight.
Before cleaning or repairing equipment, make sure that your tools are in good condition. Clean, repair, or replace items that are not functioning adequately.
Electrical Safety (18.104.22.168)
Follow electrical safety guidelines to prevent electrical fires, injuries, and fatalities.
Some printer parts become hot during use, and other parts, such as power supplies, contain high voltage. Check the printer manual for the location of high-voltage components. Some components retain a high voltage even after the printer is turned off. Make sure that the printer has had time to cool before making the repair.
Electrical devices have certain power requirements. For example, AC adapters are manufactured for specific laptops. Exchanging AC adapters with a different type of laptop or device may cause damage to both the AC adapter and the laptop.
Fire Safety (22.214.171.124)
Follow fire safety guidelines to protect lives, structures, and equipment. To avoid an electrical shock and to prevent damage to the computer, turn off and unplug the computer before beginning a repair.
Fire can spread rapidly and be very costly. Proper use of a fire extinguisher can prevent a small fire from getting out of control. Use the memory aid P-A-S-S to remember the basic rules of fire extinguisher operation:
P: Pull the pin.
A: Aim at the base of the fire, not at the flames.
S: Squeeze the lever.
S: Sweep the nozzle from side to side.
Be familiar with the types of fire extinguishers used in your country or region. Each type of fire extinguisher has specific chemicals to fight different types of fires:
Paper, wood, plastics, cardboard
Gasoline, kerosene, organic solvents
When working with computer components, be alert for odors emitting from computers and electronic devices. When electronic components overheat or short out, they emit a burning smell. If there is a fire, follow these safety procedures:
Never fight a fire that is out of control or not contained.
Always have a planned fire escape route before beginning any work.
Get out of the building quickly.
Contact emergency services for help.
Locate and read the instructions on the fire extinguishers in your workplace before you have to use them.
Procedures to Protect Equipment and Data (2.1.2)
Replacing equipment and recovering data is expensive and time consuming. This section identifies potential threats to systems and descries procedures to help prevent loss and damage.
ESD and EMI (126.96.36.199)
Replacing equipment and recovering data is expensive and time consuming. This section identifies potential threats to systems and describes procedures to help prevent loss and damage.
Electrostatic discharge (ESD) can occur when there is a buildup of an electric charge (static electricity) that exists on a surface which comes into contact with another, differently charged surface. ESD can cause damage to computer equipment if not discharged properly. Follow proper handling guidelines, be aware of environmental issues, and use equipment that stabilizes power to prevent equipment damage and data loss.
At least 3,000 volts of static electricity must build up before a person can feel ESD. For example, static electricity can build up on you as you walk across a carpeted floor. When you touch another person, you both receive a shock. If the discharge causes pain or makes a noise, the charge was probably above 10,000 volts. By comparison, less than 30 volts of static electricity can damage a computer component.
ESD can cause permanent damage to electrical components. Follow these recommendations to help prevent ESD damage:
Keep all components in antistatic bags until you are ready to install them.
Use grounded mats on workbenches.
Use grounded floor mats in work areas.
Use antistatic wrist straps when working on computers.
Electromagnetic interference (EMI) is the intrusion of outside electromagnetic signals in a transmission media, such as copper cabling. In a network environment, EMI distorts the signals so that the receiving devices have difficulty interpreting them.
EMI does not always come from expected sources, such as cellular phones. Other types of electric equipment can emit a silent, invisible electromagnetic field that can extend for more than a mile.
There are many sources of EMI:
Any source designed to generate electromagnetic energy
Man-made sources like power lines or motors
Natural events such as electrical storms, or solar and interstellar radiations
Wireless networks are affected by radio frequency interference (RFI). RFI is caused by radio transmitters and other devices transmitting in the same frequency. For example, a cordless telephone can cause problems with a wireless network when both devices use the same frequency. Microwaves can also cause interference when positioned in close proximity to wireless networking devices.
Climate affects computer equipment in a variety of ways:
If the environment temperature is very high, equipment can overheat.
If the humidity level is very low, the chance of ESD increases.
If the humidity level is very high, equipment can suffer from moisture damage.
Power Fluctuation Types (188.8.131.52)
Voltage is a measure of energy required to move a charge from one location to another. The movement of electrons is called current. Computer circuits need voltage and current to operate electronic components. When the voltage in a computer is not accurate or steady, computer components might not operate correctly. Unsteady voltages are called power fluctuations.
The following types of AC power fluctuations can cause data loss or hardware failure:
Blackout—Complete loss of AC power. A blown fuse, damaged transformer, or downed power line can cause a blackout.
Brownout—Reduced voltage level of AC power that lasts for a period of time. Brownouts occur when the power line voltage drops below 80 percent of the normal voltage level and when electrical circuits are overloaded.
Noise—Interference from generators and lightning. Noise results in poor quality power, which can cause errors in a computer system.
Spike—Sudden increase in voltage that lasts for a short period and exceeds 100 percent of the normal voltage on a line. Spikes can be caused by lightning strikes, but can also occur when the electrical system comes back on after a blackout.
Power surge—Dramatic increase in voltage above the normal flow of electrical current. A power surge lasts for a few nanoseconds, or one billionth of a second.
Power Protection Devices (184.108.40.206)
To help shield against power fluctuation problems, use devices to protect the data and computer equipment:
Surge suppressor—Helps protect against damage from surges and spikes. A surge suppressor diverts extra electrical voltage that is on the line to the ground.
Uninterruptible power supply (UPS)—Helps protect against potential electrical power problems by supplying a consistent level of electrical power to a computer or other device. The battery is constantly recharging while the UPS is in use. The UPS provides a consistent quality of power when brownouts and blackouts occur. Many UPS devices can communicate directly with the computer operating system. This communication allows the UPS to safely shut down the computer and save data prior to the UPS losing all battery power.
Standby power supply (SPS)—Helps protect against potential electrical power problems by providing a backup battery to supply power when the incoming voltage drops below the normal level. The battery is on standby during normal operation. When the voltage decreases, the battery provides DC power to a power inverter, which converts it to AC power for the computer. This device is not as reliable as a UPS because of the time it takes to switch over to the battery. If the switching device fails, the battery cannot supply power to the computer.
Figure 2-1 shows examples of devices to shield against power fluctuations.
Figure 2-1 Types of Power Protection Equipment
Procedures to Protect the Environment (2.1.3)
Most computer and peripherals use and contain at least some materials that can be considered toxic to the environment. This section describes tools and procedures that help identify these materials and the steps for proper handling and disposal of the materials.
Safety Data Sheet (220.127.116.11)
Computers and peripherals contain materials that can be harmful to the environment. Hazardous materials are sometimes called toxic waste. These materials can contain high concentrations of heavy metals such as cadmium, lead, or mercury. The regulations for the disposal of hazardous materials vary by state or country. Contact the local recycling or waste removal authorities in your community for information about disposal procedures and services.
A safety data sheet (SDS) used to be known as a material safety and data sheet (MSDS). A safety data sheet is a fact sheet that summarizes information about material identification, including hazardous ingredients that can affect personal health, fire hazards, and first-aid requirements. The SDS contains chemical reactivity and incompatibility information. It also includes protective measures for the safe handling and storage of materials and spill, leak, and disposal procedures.
To determine if a material is classified as hazardous, consult the manufacturer’s SDS. In the United States, the Occupational Safety and Health Administration (OSHA) requires that all hazardous materials be accompanied by an SDS when transferred to a new owner. The SDS information included with products purchased for computer repairs or maintenance can be relevant to computer technicians. OSHA also requires that employees be informed about the materials that they are working with and be provided with material safety information.
The SDS explains how to dispose of potentially hazardous materials in the safest manner. Always check local regulations concerning acceptable disposal methods before disposing of any electronic equipment.
The SDS contains valuable information:
Name of the material
Physical properties of the material
Hazardous ingredients contained in the material
Reactivity data, such as fire and explosion data
Procedures for spills and leaks
Special protection requirements
In the European Union, the regulation Registration, Evaluation, Authorization and restriction of Chemicals (REACH) came into effect on June 1, 2007, replacing various directives and regulations with a single system.
Equipment Disposal (18.104.22.168)
The proper disposal or recycling of hazardous computer components is a global issue. Make sure to follow regulations that govern how to dispose of specific items. Organizations that violate these regulations can be fined or face expensive legal battles. Regulations for the disposal of the items on this page vary from state to state and from country to country. Check your local environmental regulation agency.
Batteries often contain rare earth metals that can be harmful to the environment. Batteries from portable computer systems can contain lead, cadmium, lithium, alkaline manganese, and mercury. These metals do not decay and remain in the environment for many years. Mercury is commonly used in the manufacturing of batteries and is extremely toxic and harmful to humans.
Recycling batteries should be a standard practice. All batteries, including lithium-ion, nickel-cadmium, nickel-metal hydride, and lead-acid, are subject to disposal procedures that comply with local environmental regulations.
Handle CRT monitors with care. Extremely high voltage can be stored in CRT monitors, even after being disconnected from a power source.
Monitors contain glass, metal, plastics, lead, barium, and rare earth metals. According to the U.S. Environmental Protection Agency (EPA), monitors can contain approximately 4 pounds (1.8 kg) of lead. Monitors must be disposed of in compliance with environmental regulations.
Toner Kits, Cartridges, and Developers
Used printer toner kits and printer cartridges must be disposed of properly in compliance with environmental regulations. They can also be recycled. Some toner cartridge suppliers and manufacturers take empty cartridges for refilling. Some companies specialize in refilling empty cartridges. Kits to refill inkjet printer cartridges are available but are not recommended, because the ink might leak into the printer, causing irreparable damage. Using refilled inkjet cartridges might also void the inkjet printer warranty.
Chemical Solvents and Aerosol Cans
Contact the local sanitation company to learn how and where to dispose of the chemicals and solvents used to clean computers. Never dump chemicals or solvents down a sink or dispose of them in a drain that connects to public sewers.
The cans or bottles that contain solvents and other cleaning supplies must be handled carefully. Make sure that they are identified and treated as special hazardous waste. For example, some aerosol cans explode when exposed to heat if the contents are not completely used.
Figure 2-2 shows various types of hazardous computer components.
Figure 2-2 Hazardous Computer Components