System Design and Arc Flash Labeling - The Importance of Protecting Against Worker Injuries

PreparedSign.gifThe incident energy from an arc flash event can cause severe worker injuries, shut down a facility, and cripple a business. Since the electrical industry is focused on safety and reliability, it is no surprise that everyone, from engineers and system designers to facility managers and electricians, is focused on minimizing the risk of arc flash incidents.

One common practice for keeping workers safe is arc flash labeling. But with the advances in arc flash prevention/containment/mitigationsolutions, there may be some confusion regarding how to appropriately label locations. Developments such as arc flash mitigation equipment and strategies like instantaneous zone selective interlocking and reduced energy let-through technology (RELT) affect incident energy and therefore, labeling details.

Arc flash labeling requires properly identifying the electrical system incident energy available during an arc flash event and labeling equipment accordingly. This first step enables operators to develop proper workplace safety procedures, like the use of personal protective equipment (PPE). The labeling requirements are in accordance to the National Fire Protection Agency under NFPA 70E 130.5 arc flash Hazard Analysis (2012 Edition) standards:

(C)  Equipment Labeling. Electrical equipment such as switchboards, panelboards, industrial control panels, meter socket enclosures, and motor control centers that are in other than dwelling units and are likely to require examination, adjustment, servicing, or maintenance while energized, shall be field marked with a label containing all the following information:

 (1) At least one of the following:

a.  Available incident energy and the corresponding working distance

b. Minimum arc rating of clothing

c.  Required level of PPE

d.  Highest Hazard/Risk Category for the equipment

(2) Nominal system voltage

(3) Arc flash boundary

Exception: Labels applied prior to September 30, 2011, are acceptable if they contain the available incident energy or required  level  of PPE. The method of calculating and data to support the information for the label shall be documented.

Some industry experts believe a good safety label should go a bit further and contain more details. Below is a sample GE label that includes additional information companies should consider for their labels, such as study date, case number, equipment description, and name.

Equipment construction and system-wide strategies affect labe