Section 110.16 of the National Electric Code requires a label on electrical equipment that warns qualified persons of potential arc flash hazards if that equipment is likely to require examination, adjustment, servicing, or maintenance while energized.
As part of the 2014 code change process, the requirements for arc flash warning markings have been modified yet again, and section 110.16 has been revised.
A new subsection has been added to this part of the code to establish a criteria for the use of field applied markings, and a small revision to Section 110.16 now allows for markings to be applied at the factory.
New Subsection 110.21(B): Field-Applied Markings
Various sections of the NEC require field marking using one of these signal words: "DANGER", "WARNING", or "CAUTION." The new subsection seeks to provide consistency in the required marking by establishing a visual format, durability, and suitability criteria.
Red background and exclamation point: Indicates an imminently hazardous situation which, if not avoided, will result in death or serious injury. Section 110.34(C) requires this marking for equipment rated above 600V.
Orange background and exclamation point: Indicates a potentially hazardous situation which, if not avoided, could result in death or serious injury.
Yellow background and exclamation point: Indicates a potentially hazardous situation which, if not avoided, may result in minor or moderate injury. The signal word "caution" without the safety alert symbol (triangle with exclamation point) is sometimes used when the message addresses only a hazard to property and not to persons.
Requirements for Labels and Markings
This new subsection requires that labels and markings shall adequately warn of the hazard using effective words and/or colors and/or symbols.
- The label shall be permanently affixed to the equipment or wiring method and shall be of sufficient durability to withstand the environment involved.
- Labels should never be hand written, except where they are variable or could be subject to change.
Informational notes in this subsection reference ANSI Z535.4-2011, Product Safety Signs and Labels, which provides guidelines for suitable font sizes, words, colors, symbols, and placement requirements for safety signs and labels.
Markings shall include a description of the arc flash hazard, a way to avoid the hazard, and consequences if ignored.
Updates to NEC Section 110.16: Arc Flash Hazard Warning
Arc flash warning labels may now be field or factory applied. Field-applied marking shall meet the requirements of new the new 110.21(B) subsection, which contains general requirements for field marking as discussed above.
Many manufacturers are marking equipment with appropriate arc flash warning labels, so there is no need for field marking. The equipment installer, however, is ultimately responsible for compliance with this section.
The code still does not specify the content and details of the warning label, since this information is deemed related to workplace safety rather than installation, and is therefore beyond the scope of the NEC.
Informational Note No. 1 in this section makes reference to NFPA 70E-2012, Standard for Electrical Safety in the Workplace, which provides guidance in determining the level of exposure, planning safe work practices, arc flash labeling, and selecting personal protective equipment (PPE).
Informational Note No. 2 references ANZI Z535.4, Product Safety Signs and Labels for guidelines for the design of safety sign and labels.
Which type of equipment should have arc flash warning labels?
NEC Section 110.16 states that switchboards, switchgear, 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, require a label that warn qualified persons of potential arc flash hazards.