Electrical Shock Protection

Electrical shock caused by working on equipment while it is still plugged into AC power can be lethal. Power should always be disconnected from a PC while it is being upgraded or repaired. Note that ATX and all other power supplies that use the 20/24-pin ATX power connector are actu-ally in a low-voltage standby mode when the computer is turned “off.”

Remove jewelry (chains, rings, watches, and so on) while working on a PC or other computer equipment. Wearing metal objects improve the odds of receiving a dangerous or deadly shock.

Lifting and Moving Equipment Safely

When lifting heavy objects such as computers, laser printers, and CRTs, use safe lifting tech-niques. Always lift with your legs and keep your back straight. Rotate by moving your feet, not by twisting your back.

Know your own weight-lifting limitations. Get an associate to help you, or use a wheeled cart or dolly to help move an object that is too heavy for you to lift safely.

Chapter 5: Operational Procedures 93

Fighting Electrical Fires Safely

Standard Class AB fire extinguishers are useless against electrical fires and can cause shock haz-ards. However, a Class ABC-rated fire extinguisher can be used safely and effectively against elec-trical fires. The following explains the classes:

Class A is for paper and wood fires.

Class B is for flammable liquid (grease, gasoline, and so on) fires. Class C is for electrical fires.

A Class ABC extinguisher should be marked as such, but the markings are sometimes symbols:

Class A—Garbage can and wood symbolClass B—Gas can symbol

Class C—Electrical plug symbol

Safe Disposal of CRT Displays

CRTs contain capacitors that can retain lethal levels of voltage for quite some time after being removed from service. Do not open a CRT. If you want to have it repaired, have a repair depart-ment experienced in the safe repair of CRTs perform the work.

However, it is much more likely today that you will replace the unit with a modern LCD or LED display. Do not discard the display, because the magnets, lead, and other components represent toxic waste. Instead, recycle the unit through an authorized electronics recycling facility.

Cable Management

To prevent fall and trip hazards and the potential for damage to computers and other equipment, cable management should be practiced in both permanent installations and temporary work areas.

Depending on the situation, cable management can be as simple as the use of hook-and-loop (Velcro brand and others) to secure excess cable lengths and taping down cables in temporary installations to the use of floor cable covers, wall and ceiling mounted cable raceways, and cable looms to gather a computer’s cables into a convenient bundle.

Installation Regulations

Be sure to follow local government regulations that govern the types of cable that can be used in certain environments (for example, plenum versus PVC network cable) and who should install it. In some localities, a licensed cable installer may need to perform this work.

94 CompTIA A+ Quick Reference