Lesson 2: Safety and the Environment

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Lesson 1 discussed several ways in which to keep a computer's hardware running at peak performance. When maintaining or servicing a computer, several guidelines should be followed to protect you and the environment. This lesson summarizes how to maintain a safe workplace and minimize negative impacts on the environment.

After this lesson, you will be able to:

  • Prepare a safe work environment and prevent damage to the computer, yourself, and the environment.
  • Manage the components of a computer that have negative effects on our environment.
Estimated lesson time: 15 minutes

General Safety

Computers and their peripheral devices are electronic equipment, consequently, most safety issues relate to electrical power. However, when you work on this equipment, there are several other concerns to take into consideration, as listed in the following table.

Problem Prevention
Back injuries Some equipment, such as printers, monitors, and even the computer itself, can weigh several pounds (10 to 20 pounds or more for newer, larger monitors). This might not seem like much; however, when the equipment is improperly picked up (or dropped), back or other injuries can result. Be especially careful when removing a component from its original packaging. These components are generally packaged very tightly to provide protection during transport and can be difficult to remove.
Cuts Be very careful when removing covers from computer components. The frames of the cases are often made of thin metal with sharp edges. Also, poorly cut or stamped parts might still have metal burrs, which are very sharp. Devices such as scanners and monitors have glass components that can break.
Tripping hazards Computers tend to have many cables and wires. If not properly installed, these wires and cables can constitute a serious tripping hazard. Use cable ties to bundle up cables and reduce the "spaghetti" effect. Also avoid running cables under carpets and where people walk.

When installing or working on any equipment, make sure that the work done conforms to all applicable local and national safety codes, such as OSHA (Occupational Safety and Health Administration) and NEC (National Electric Code) standards. Most companies have their own internal safety departments and safety manuals. Be sure that you are familiar with them as well.

Power and Safety

Power is the primary safety hazard encountered when servicing a computer. Be familiar with the following guidelines when working with electrical devices and components.


The primary electrical-power concern when working with computers is ESD (electrostatic discharge). This subject was covered fully in Chapter 13, "The Basics of Electrical Energy." Remember that while ESD can destroy sensitive computer parts even when the discharge is imperceptible and harmless to humans. If proper ESD tools are not available, touching the case (specifically, the power supply) while working on the computer or its components will provide some protection. However, this will only work if the power supply is plugged into a properly grounded electrical outlet. For a review of power supplies and how to work with them, see Chapter 5 "Supplying Power to a Computer."


When used to refer to electronic equipment, the term "ground" can be confusing. Generally speaking, a ground is any point from which electrical measurements can be made. In most cases, a ground means earth ground. With early electrical systems, the earth was used as a path for electrical current to return to its source. This is why telegraphs required only one wire (the earth ground serves as the other conductor). In most instances, the frame of the computer is at ground potential or earth ground, as long as the power cord is installed and connected to a properly grounded system. Some electronic equipment uses a special path or conductor for its ground. This is known as signal ground and is not the same as earth ground.

Electronic equipment is both susceptible to and a source of electromagnetic interference (EMI). A properly grounded computer will both prevent the transmission of EMI and protect itself from other sources of EMI. Unchecked, EMI will distort images on a video display, as well as corrupt communications equipment and data on floppy disks.

High Voltages

For the most part, a computer uses ±5 and ±12 volts DC. However, two devices use much higher voltages: power supplies and monitors. With these two exceptions, there are generally no electrical hazards inside a computer.

Power Supplies

The power supply uses 120 volts AC. This voltage is found inside the power-supply case. In most cases, there is no need to open the power-supply case and work on the power supply. The cost of a new power supply is low enough that it is generally easier to replace than repair. However, should you decide to open the case, be careful. Remember, the power switch on most computers (usually located on the front of the computer) also uses 110 volts AC to turn the power supply on or off. If you are working on a computer and leave it plugged in to provide proper grounding, this could present a hazard.


Monitors use very high voltages (30,000 volts) to drive the CRT. Remember that monitors are dangerous even when unplugged. They can store this high voltage and discharge it if you touch the wrong parts. Working inside the monitor case should be left to a properly trained technician with the necessary tools.

Power Safety Guidelines

The following are some general guidelines to follow when working around computers:

  • Never wear jewelry or other metal objects when working on a computer. These items pose an electrical threat that can cause shorts, which will destroy components.
  • To avoid spills, never use liquids around electrical equipment.
  • Do not defeat the safety feature of the three-prong power plugs by using two-prong adapters.
  • Replace any worn or damaged power cords immediately.
  • Never allow anything to rest on a power cord.
  • Avoid using extension cords. These can become tripping hazards. Also, they may not be rated to carry the current requirements of the system.
  • Keep all electrical covers intact.
  • Make sure all vents are clear and have ample free-air space to allow heat to escape.
  • Some peripheral devices such as laser printers and scanners use high voltages. Before removing any covers or working on any of these devices, be sure to read the manufacturers' manuals carefully.


Fire is not pleasant to think about, but it is a fact of life. A workplace fire can be disastrous both in terms of lost equipment and injury to people. Knowing what to do in the event of a fire can save valuable equipment and, most importantly, lives. Here are a few tips to help prevent fire and protect yourself:

  • Always know the emergency procedures to be carried out in case of fire at your workplace.
  • Know the location of the nearest fire exits.
  • Know the location of the nearest fire extinguishers and how to use them.
  • Don't overload electrical outlets.

Simply knowing the location of a fire extinguisher is of no value unless you know how to use it. If you don't, contact your safety department or local fire department. They will be glad to help you get the training you need. Also, remember that using the wrong type of fire extinguisher can be worse than not using one at all.

There are three basic types of fire extinguishers as shown in Figure 19.1.

click to view at full size.

Figure 19.1 Fire extinguisher types

Environmental Issues

Many computers and peripheral devices (especially printers) use consumable or recyclable components. In order to help keep our environment safe, you should be aware of these items and use them properly.

Examples of recyclable items or items that require special disposal are:

  • Batteries.
  • Toner and cartridge kits.
  • Circuit boards.
  • Chemical solvents.
  • Monitors (CRTs).

Be sure to follow the manufacturers' recommendations for recycling or disposal of any of these items. Some items, such as toner cartridges even have prepaid shipping labels so that they can be returned for proper disposal.

When purchasing or using any kind of chemicals (cleaners, for example) that you are not familiar with the proper use and disposal of, be sure to check the MSDS (material safety data sheet). This is a form that describes the nature of any chemicals manufactured. It includes generic information about the product's chemical makeup and any recognized hazards (including what to do and who to call if there is a problem). These forms are required by law, so ask to see them. Chemical suppliers must provide the purchaser with the MSDS for products, if requested. Also consider purchasing sprays with a manual pump dispenser or compressed air rather than CFCs or other propellants that can be harmful to the environment.

Lesson Summary

The following points summarize the main elements of this lesson:

  • Electrical safety is your responsibility—know what is dangerous and how to be safe.
  • Beware of potential ESD problems, and maintain good electrical grounds.
  • Know where your fire extinguishers are and how to use them.
  • If in doubt about particular chemicals, ask the vendor for the MSDS and be sure to read it.
  • Choose chemicals that are safe for the environment.

Microsoft Corporation - A+ Certification Training Kit
Microsoft Corporation - A+ Certification Training Kit
Year: 2000
Pages: 127

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