The 1997 version of the National Electrical Safety Code ("NESC"), for the first time references a particular design standard for sign design and gives detailed information on when to use a sign. The NESC is incorporated by many municipalities as part of their building code. The NESC is adopted by reference by statute or regulation in most states, and is regularly used by the few states without direct adoption. The NESC as been adopted by the US Army Corp of Engineers, the Rural Utilities Service of the US Department of Agriculture (for use by electric and communication cooperative utilities), the American Public Power Association (for use by municipal utilities and public power districts) and similar groups. As such, compliance is needed for building inspection, commercial exemptions, insurance coverage, etc. Although the NESC Standard C2-1997 does not describe specific requirements for sign legends or designs, it specifically references the ANSI Z535 sign, tag and label standards and leaves much of the explanation of sign design to Appendix B of the accompanying NESC Handbook. In the NESC Handbook, you will find a number of typical sign designs.

The NESC references the 1991 Z535 standards. Subsequent research showed that some of the new formats first promulgated in the 1991 Z535 standards work better than some of the formerly preferred formats. All of the formats shown as preferred formats in the 1998 Z535 standards were allowed formats in the 1991 standards. As a result, utilities should use the 1998 standards, and will be in accordance with the 1997 NESC by doing so. As mentioned in this Appendix, though, the underlying ANSI standards have also changed and, as a result, the sign designs need further modifications. Using the 1998 Z535 standards for new signs and labels will limit the opportunity for the new utility signs or labels to be outmoded in the near future.  


Illustration from video is reproduced courtesy of Clapp Research, Inc., Engineering.

Follow the NESC guidelines for sign placement. The NESC requires a safety sign at each entrance to an electric supply station and on each side of the fence. ANSI Z535.2 specifies viewing distances for different letter heights. For many signs, multiple signs will be needed to assure visibility from all expected avenues of approach. Typically, for the letter heights often used, signs should be attached on each side of the substations, at 50 foot intervals. Signs should also be placed near entrances.

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