From marking equipment and conductors at the factory to field-marking with signs where electrical hazards exist, there are hundreds, if not thousands, of marking requirements in the National Electrical Code (NEC). Based on a proposal for the 2014 NEC that Code-Making Panel 1 accepted into Article 110 and the subsequent acceptance of other proposals, the NEC will require field-applied caution, warning and danger signs to be color-coded, indicating the type of hazard workers may encounter.

Panel 1 accepted, in principle and in part, Proposal 1-114 Log No. 847 with new mandatory text in new subpart (B) and a new informational note in 110.21. The panel accepted adding a new section title of 110.21 (A) Manufacturer Markings and added the words “or label” after “marking” in the final sentence of (A). The text that the panel accepted is as follows with new text underlined: “110.21(A) Manufacturer Markings. The manufacturer’s name, trademark, or other descriptive marking by which the organization responsible for the product can be identified shall be placed on all electrical equipment. Other markings that indicate voltage, current, wattage, or other ratings shall be provided as specified elsewhere in this Code. The marking or label shall be of sufficient durability to withstand the environment involved.

“(B) Field-Applied Markings. Where caution, warning, or danger signs or labels are required by this code, the labels shall meet the following requirements.

“(1) The following colors shall be used for the hazard labels.

“(a) DANGER Label: Black text, with white and red background

“(b) WARNING Label: Black text with white and orange background

“(c) CAUTION Label: Black text with yellow and white background

“(2) The label shall be permanently affixed to the equipment or wiring method and shall not be hand written.

“(3) The label shall be suitable for the environment where it is installed.

“Informational Note: ANSI Z535.4-2011, Product Safety Signs and Labels, provides guidelines for the design and durability of safety signs and labels for application to electrical equipment. This standard provides more specific information related to suitable font sizes, colors, various symbols and location requirements for labels.”

The first paragraph primarily remains the same as in previous NEC editions and applies only to manufacturer’s markings for electrical equipment. The added text in new (B) is labeled as “field applied markings” and only applies where other sections of the NEC require field marking of wiring methods, equipment and installations with the hazard commands of danger, warning or caution. As noted in the accepted text, the danger label or sign will have black text with white and red background; the warning label or sign must have black text with white and orange backgrounds; and the caution label or sign must have black text with yellow and white background. The intent of this change is to provide a standardized label application and remove the inconsistencies in signs and labels that exist in installations. The informational note at the bottom of new (B) references ANSI Z535.4 2011, covering product safety signs and labels with appropriate font sizes, signage colors, consistent symbols and location requirements. Although specific colors are not designated by the ANSI Z535.4 standard, the proposed text mandates required colors that are consistent with the industry best and most common practices.

An example of these signage or label requirements’ intended locations are in 110.27(C), covering warning signs. It states, “entrances to rooms and other guarded locations that contain exposed live parts shall be marked with conspicuous warning signs forbidding unqualified persons to enter,” will have an added sentence at the end of the section, stating, “the marking shall meet the requirements in 110.21(B).” This warning sign must have black text with white and orange backgrounds.

In 110.34(C), the issue deals with danger signs and would then read as follows: “Where the voltage exceeds 600-volts, nominal, permanent and conspicuous danger signs shall be provided. The danger sign shall meet the requirements in 110.21(B) and shall read as follows:

DANGER—HIGH VOLTAGE—KEEP OUT.” The required color-coding for the danger signs will be black text with a white and red background.

These color-coded signs should help the field person automatically decide what level of hazard exists based on the background color with the most hazardous being red, the next most hazardous being orange and the least being yellow. Many facilities will be faced with a decision of changing existing signs to match new signs being installed for consistency. While the NEC is not retroactive, safety considerations may dictate changing the signs.


ODE is a staff engineering associate at Underwriters Laboratories Inc., based in Peoria, Ariz. He can be reached at 919.949.2576 and mark.c.ode@us.ul.com.