Some of the first things that stand out before entering an electrical room is the general cleanliness of the environment. Are they cluttered? Are there trip hazards? Is it a dual-purpose storage room/electrical room? Other things to consider is the condition of the equipment itself. Is it clean? Does it have open doors or cardboard? Is there moisture apparent? If the answer to any of these is yes, then you probably don’t want to be near the equipment.
A shock boundary deals with voltage shock and voltage class. This includes limited approach boundary and restricted approach. These boundaries will be identified and posted on the equipment. Limited approach boundary is the line measured in feet and inches from exposed parts that unqualified people shall not cross. Exposed parts include a piece of equipment that is energized and has pieces of bus or equipment that are visible, like opening a door or cover. Restricted approach boundary is typically less distance, also dealing with exposed parts. Only qualified people may pass this boundary.
The Arc Boundary is a boundary that is established form the live exposed parts. This boundary is calculated to where if an Arc occurs, the person will receive 2nd degree burns at this distance. Equipment should be labeled with this boundary as well. Without the proper PPE inside this boundary, you are putting yourself at risk to this arc flash event.
A qualified person is defined by NFPA 70E as someone who has the general skills and knowledge related to the specific construction and operation of the equipment and understands the hazards of the equipment. They have been trained on the equipment and are familiar with it. Electricians and building managers are good examples of qualified personnel. This should be the absolute baseline of criteria for who can enter these areas.
Some minimum awareness and training before entering an electrical room can include an understanding of NFPA 70E standards. This includes the different boundaries outlined above. You might also want to familiarize yourself with the equipment you’re expected to see inside the facility.
One of the most important guidelines that everyone should practice is to not touch equipment. You never know the condition of the equipment and whether it is energized. Depending on the age and condition of the equipment you could cause a deadly arc just by touching the equipment. When a qualified person is working on equipment, you should ensure that you are outside of the arc flash and limited approach boundaries, unless you are in proper PPE and a qualified person.
By following these general outlines you greatly increase your personal safety and also the safety of others around you.