The 2008 NEC® - Detailed Arc Flash Warning Labels Still not Required.

The 2008 NEC® - Detailed Arc Flash Warning Labels Still not Required.
Jim Phillips, P.E.

Nov 7, 2006

It looks as though detailed arc flash warning labels, which typically include the calculated incident energy and approach boundaries will not be required in the 2008 NEC®. There has been much discussion and debate about requiring the detailed labels but so far, not everyone is in agreement.

Presently, Article 110.16 of the 2005 NEC® only requires that labels warn qualified persons of potential electric arc flash hazards. The typical label looks like the one shown below.





The warning does not provide specific information about the degree of hazard, the required personal protective equipment (PPE) or other important details. However, only “Qualified Persons” are permitted to approach the live equipment. NFPA 70E Article 110.6 (D) (1) defines a Qualified Person as one who is "trained and knowledgeable… to recognize and avoid the electrical hazards." This definition includes "being familiar with the proper use of the precautionary techniques, personal protective equipment, including arc-flash, insulating and shielding materials, and insulated tools and test equipment."

Therefore, the main objective is that no one should be working on or near the energized equipment unless they are qualified. Of course, it is always the preferred option to place the equipment in an "electrically safe condition".

In lieu of detailed calculations and studies, NFPA 70E, Standard for Electrical Safety in the Workplace, allows the use of Tables for the selection of Personal Protective Equipment.

Even though detailed arc flash studies are not a code requirement, many companies have elected to conduct them anyway to have a better idea of the hazard that exists.

The study results are then included on detailed labels like the one shown below. These labels contain information such as:

* Flash Hazard Boundary
* Incident Energy
* PPE Level
* Shock Protection Boundaries



IEEE 1584 calculations are generally used for the arc flash study which can be a complex endeavor. Short circuit data, device clearing times from coordination studies, and other details are required for a complete effort.