Identifying Arc Flash Hazards
Proposed changes to NFPA 70E® seek to revise arc flash warning labels.
NFPA Journal®, May/June 2008
This is our new column on NFPA 70E, Electrical Safety in the Workplace®.
Since arc flash labels were first required in 2002, there have been many differences throughout the industry between the wording and the choice of signal word and color. The 2009 edition of NFPA 70E, Electrical Safety in the Workplace, will require, for the first time, that one of two pieces of information be on the label: either the required level of personal protective equipment (PPE) to wear or the available incident energy. However, it leaves the color and signal word of the label and any other information the facility wants to put on the label up to the discretion of facility management.
A bit of label history
The requirement to field-mark certain electrical equipment to warn of potential arc flash hazards was first introduced in Section 110-16 of the 2002 National Electrical Code® (NEC®), which stated that "switchboards, panelboards, industrial control panels and motor control centers that are in other than dwelling occupancies and are likely to require examination, adjustment, servicing, or maintenance while energized shall be field-marked to warn qualified persons of potential electric arc flash hazards." Section 110-16 further required "the marking… be located so as to be clearly visible to qualified persons before examination, adjustment, servicing, or maintenance of the equipment…." Arc flash markings were first mentioned in the 2004 edition of NFPA 70E in Section 400.11, which used the wording found in the 2002 NEC.
Labels using 70E-2009
For the 2009 edition of NFPA 70E, it was proposed to delete Chapter 4, which includes the label requirements of Section 400.11. A new Section 130.3(C), Equipment Labeling, will be added that states, "Equipment shall be field-marked with a label containing the available incident energy or required level of PPE." The Section 400.11 requirement to warn persons of potential electric arc flash hazards, a listing of the types of equipment requiring marking, and the Fine Print Note (FPN) suggesting ANSI Z535.4 guidelines will no longer exist. The NEC will still cover those requirements. If you combine the requirements of the Section 110.16 of the 2008 NEC with the requirements of Section 130.3(C) of NFPA 70E, you have a total requirement that lists which equipment to mark and what information to put on the marking. Just like the qualifier in NEC Section 110.26 concerning the need for working space, the phrase "are likely to require examination, adjustment, servicing, or maintenance while energized" can help in deciding which equipment to mark.
To mark equipment with either the required level of PPE or the available incident energy, a working distance must be assumed. Although not required by NFPA 70E, there is no prohibition against adding the working distance assumed on the label. It could also be included somewhere else in the organization’s hazard/risk analysis for the tasks to be done at that piece of equipment.
What to use on the label
Both RED/DANGER and ORANGE/WARNING labels are available and in use on equipment. Both NFPA 70E and the 2008 NEC are silent on the choices for colors and signal words required, but FPN 2 after NEC Section 110.16 notes that ANSI Z535.4-1998 provides guidelines for the design of warning labels:
DANGER: Indicates a hazardous situation that, if not avoided, will result in death or serious injury. This signal word is to be limited to the most extreme situations.
WARNING: Indicates a hazardous situation that, if not avoided, will result in death or serious injury.
The word DANGER shall be in safety white letters on a safety red background
The word WARNING shall be in safety black letters on a safety orange background
There is no difference between the DANGER and WARNING signal words except that DANGER "is to be limited to the most extreme situations." For this reason, using RED DANGER labels throughout a facility would be inappropriate. These labels should be reserved for only the most extreme situations.
What are the most extreme situations? The FPN in NFPA 70E Section D.8 states, "When incident energy exceeds 40 cal/cm2 at the working distance, greater emphasis should be placed on de-energizing before working on or near the exposed electrical conductors or circuit parts." Although FPNs are not requirements, this note provides a criterion for identifying an extreme situation. ANSI Z535.4 guidelines require a RED DANGER signal word where the incident energy level is above 40 cal/cm2.
Although ANSI Z535.4 is only a recommended guideline in the NEC and not referenced in NFPA 70E, using it would help workers distinguish locations in which the incident energy level is very high.
Bill Buss is senior electrical engineer for NFPA.