This requirement was revised in the 2008 Code by adding the words ?Electrical equipment, such as? to make it clear that the requirement was not limited to the equipment on the list. Arc flash hazards could exist in other equipment. Field marking that warns electrical workers of potential electrical arc flash hazards is required because significant numbers of electricians have been seriously burned or killed by accidental electrical arc flash while working on ?hot? (energized) equipment. Most of those accidents could have been prevented or their severity significantly reduced if electricians had been wearing the proper type of protective clothing. Requiring switchboards, panelboards, and motor control centers to be individually field marked with proper warning labels will raise the level of awareness of electrical arc flash hazards and thereby decrease the number of accidents.
Exhibit 110.7 shows an electrical employee working inside the flash protection boundary and in front of a large-capacity service-type switchboard that has not been de-energized and that is not under the lockout/tagout procedure. The worker is wearing personal protective equipment (PPE) considered appropriate flash protection clothing for the flash hazard involved. Suitable PPE appropriate to a particular hazard is described in NFPA 70E, Standard for Electrical Safety in the Workplace.
Exhibit 110.8 displays one example of a warning sign required by 110.16.
Accident reports continue to confirm the fact that workers responsible for the installation or maintenance of electrical equipment often do not turn off the power source before working on the equipment. Working electrical equipment energized is a major safety concern in the electrical industry. The real purpose of this additional Code requirement is to alert electrical contractors, electricians, facility owners and managers, and other interested parties to some of the hazards of working on or near energized equipment and to emphasize the importance of turning off the power before working on electrical circuits.
Exhibit 110.7 Electrical worker clothed in personal protective equipment (PPE) appropriate
for the hazard involved.
Exhibit 110.8 One example of an arc flash warning sign required by 110.16. (Courtesy of the
International Association of Electrical Inspectors)
The information in fine print notes is not mandatory. Employers can be assured that they are providing a safe workplace for their employees if safety-related work practices required by NFPA 70E have been implemented and are being followed. (See also the commentary following the definition of qualified person in Article 100.)
In addition to the standards referenced in the fine print notes and their individual bibliographies, additional information on this subject can be found in the 1997 report ?Hazards of Working Electrical Equipment Hot,? published by the National Electrical Manufacturers Association.