N10-007 Summarize safety practices

Electrical safety

Shielding refers to the process of preventing electronic emissions from your computer systems from being used to gather intelligence and preventing outside electronic emissions from disrupting your information-processing abilities. In a fixed facility, such as a computer center, surrounding the computer room with a Faraday cage can provide electronic shielding. A Faraday cage usually consists of an electrically conductive wire mesh or other conductor woven into a “cage” that surrounds a room.

The conductor is then grounded. Because of this cage, few electromagnetic signals can either enter or leave the room, thereby reducing the ability to eavesdrop on a computer conversation. To verify the functionality of the cage, radio frequency (RF) emissions from the room are tested with special measuring devices.

Electromagnetic interference (EMI) and radio frequency interference (RFI) are two additional environmental considerations. Motors, lights, and other types of electromechanical objects cause EMI, which can cause circuit overload, spikes, or electrical component failure. Making sure that all signal lines are properly shielded and grounded can minimize EMI. Devices that generate EMI should be as physically distant from cabling as is feasible because this type of energy tends to dissipate quickly with distance.


ESD first requires a build-up of an electrostatic charge. This occurs when two different materials rub together. One of the materials becomes positively charged; the other becomes negatively charged. The positively-charged material now has an electrostatic charge. When that charge comes into contact with the right material, it is transferred and we have an ESD event. The heat from the ESD event is extremely hot, although we do not feel it when we are shocked. However, when the charge is released onto an electronic device such as an expansion card , the intense heat from the charge can melt or vaporize the tiny parts in the card causing the device to fail. Sometimes an ESD event can damage a device, but it continues to function. This is a called a latent defect, which is hard to detect and significantly shortens the life of the device

Many electronic devices are susceptible to low voltage ESD events. For example, hard drive components are sensitive to only 10 volts. For this reason, manufacturers of electronic devices incorporate measures to prevent ESD events throughout the manufacturing, testing, shipping, and handling processes. For example, an employee may wear a wrist strap when working with devices or may wear ESD control footwear and work on an ESD floor mat that causes the electrostatic charge to go into the ground instead of into the device. Sensitive devices can be packaged with materials that shield the product from a charge.

Installation safety

To prevent bodily injury when mounting or servicing this unit in a rack, you must take special precautions to ensure that the system remains stable. The following guidelines are provided to ensure your safety:

  • This unit should be mounted at the bottom of the rack if it is the only unit in the rack.
  • When mounting this unit in a partially filled rack, load the rack from the bottom to the top with the heaviest component at the bottom of the rack.
  • If the rack is provided with stabilizing devices, install the stabilizers before mounting or servicing the unit in the rack.

Observe the following precautions for rack stability and safety. Also refer to the rack installation documentation accompanying the rack for specific warnings and caution statements and procedures.

  • Do not move large racks by yourself. Due to the height and weight of the rack, a minimum of two people are needed to accomplish this task.
  • Ensure that the rack is level and stable before extending a component from the rack.
  • Do not overload the AC supply branch circuit that provides power to the rack. The total rack load should not exceed 80% of the branch circuit rating.
  • Do not step or stand on any system or component when servicing other systems and components in a rack.
  • This unit should be mounted at the bottom of the rack if it is the only unit in the rack.
  • When mounting this unit in a partially filled rack, load the rack from the bottom to the top with the heaviest component at the bottom of the rack.
  • If the rack is provided with stabilizing devices, install the stabilizers before mounting or servicing the unit in the rack.
  • Enclosed racks must have adequate ventilation. Make sure the rack is not overly congested because each chassis generates heat. An enclosed rack should have louvered sides and a fan to provide cooling air.
  • When mounting a chassis in an open rack, make sure the rack frame does not block the intake or exhaust ports. If the chassis is installed on slides, check the position of the chassis when it is seated all the way into the rack.
  • In an enclosed rack with a ventilation fan in the top, excessive heat generated by equipment near the bottom of the rack can be drawn upward and into the intake ports of the equipment above it in the rack. Make sure you provide adequate ventilation for equipment at the bottom of the rack.
  • Baffles can help to isolate exhaust air from intake air, which also helps to draw cooling air through the chassis. The best placement of the baffles depends on the airflow patterns in the rack. Experiment with different arrangements to position the baffles effectively.

A Material Safety Data Sheet (MSDS) is a document that contains information on the potential hazards (health, fire, reactivity and environmental) and how to work safely with the chemical product. It is an essential starting point for the development of a complete health and safety program. It also contains information on the use, storage, handling and emergency procedures all related to the hazards of the material. The MSDS contains much more information about the material than the label. MSDSs are prepared by the supplier or manufacturer of the material. It is intended to tell what the hazards of the product are, how to use the product safely, what to expect if the recommendations are not followed, what to do if accidents occur, how to recognize symptoms of overexposure, and what to do if such incidents occur.

Emergency procedures

  • Even with the best of precautions, environmental issues and accidents involving computers and related technologies can and do happen. Use the following procedures to handle problems safely and professionally
  • Know who to contact in case of injuries to personnel, damage to equipment, fires, or chemical spills.
  • Know how to reach an outside phone line to call 911 in case of serious emergency.
  • Review and follow procedures for cleaning up chemical spills, retrieving damaged computer equipment, or other problems.
  • Have MSDS information available for computer-related supplies and chemicals.
  • Write up the incident in a professional manner, noting time, place, personnel involved, and other important information.
  • Work with other personnel to solve problems resulting from the incident.
  • Learn from the incident to help avoid future problems.


If the computer systems for which you’re responsible require special environmental considerations, you’ll need to establish cooling and humidity control. Ideally, systems are located in the middle of the building, and they’re ducted separately from the rest of the HVAC (Heating, Ventilation, and Air Conditioning) system. It’s a common practice for modern buildings to use a zone-based air conditioning environment, which allows the environmental plant to be turned off when the building isn’t occupied. A computer room will typically require full-time environmental control.

Fire suppression

Fire suppression is a key consideration in computer-center design. Fire suppression is the act of extinguishing a fire versus preventing one. Two primary types of fire-suppression systems are in use: fire extinguishers and fixed systems.