Designing by the Code

In July’s Code Corner, we discussed the location of motor/controller disconnecting means as required by Section 430-102. By the very nature of these provisions, one could argue that location selection is essentially a design issue that ultimately should be left to the electrical engineer or designer. At what point do such issues, which have important safety implications, override the exclusion of design criteria within the National Electrical Code (NEC)? In other words, are there provisions that the NEC should address, even if they have design implications? This scope of the issue goes well beyond the location of motor/controller disconnecting means. Many installation requirements in the NEC could be considered borderline “design” criteria. History For over 60 years, the NEC’s language strongly supported the notion that the NEC is not a design manual. Since the 1937 NEC, the Code has stated it “is not intended as a design specification nor an instruction manual for untrained persons.” Note that the provision contains two important requirements. First, consider the requirement that the Code is not intended as a design specification. Second, notice that it is not intended as an instruction manual for untrained persons. Are the two requirements related? For example, one could read the two requirements as a single one. The Code is intended as neither a design specification nor an instruction manual for untrained persons. If the requirements are read as a single requirement, then both conditions are qualified by the reference to “untrained person.” Presumably, one could argue then, that the Code is suitable as a design specification for an instruction manual for trained persons. Or, the two requirements could be interpreted separately. First, the Code is not intended as a design specification. Second, it is not intended as an instruction manual for untrained persons. Perhaps the requirement’s history is far less significant than how it has been interpreted and understood. Clearly, very few would argue today that the Code is intended as a design specification, even if it presently includes some design provisions. Many, however, would argue that it contains design specifications necessary for safety. The instruction manual provision is another question. Each year, thousands of new apprentices study and use the Code as an instructional manual. But again, few would argue that the Code is an instruction manual in the truest sense of the word. We will save that question for another day. 2002 Proposed revision During the most recent few Code cycles, a few attempts were made to revise this important section of the NEC. During the 1999 Code cycle, one proposal suggested revising the section to read as follows: “This Code is not intended as a design specification but includes such provisions where considered necessary for safety. It is not intended as an instruction manual for untrained persons.” The submitter argued “(S)ection 90-1 only states that it is “not intended” as a design specification. It does not state that such provisions are not permitted to be included. The Code presently includes many provisions that relate to design. In many cases, it is necessary to include design requirements in order to provide an important safety rule.” Code-making Panel (CMP)-1 initially accepted, then retracted, its acceptance of the proposed revision and stuck by the historical understanding of this section. Interestingly, during the early stages of the 2002 NEC, CMP-1 has once again accepted a proposed revision to this section. This time, the Panel vote was nine to three in favor of completely deleting Section 90-1. The substantiation submitted with the proposal stated in part that, “‘(T)here have been occasions where the wording in Section 90-1 has been used to oppose the addition of Code rules because they included requirements involving design criteria even though the objective of those rules was safety. Many rules included in the Code are design in nature but still fall within the ‘practical safeguarding of persons and property from hazards arising from the use of electricity.’” Analysis Notice the emphasis that the submitter of the 2002 proposal placed on safety as it relates to the question of design and the purpose of the Code. This is the fundamental litmus test for any Code provision; does it pass the 90-1 (a) test? Will the proposed revision to the Code assist or detract from its stated purpose? One CMP-1 member felt very strongly that the deletion would be harmful. His statement accompanying his negative vote pointed out, “(T)he present wording (90-1) provides all CMPs with a much-needed and desired reference in dealing with design proposals to the NEC. There is no technical substantiation to try and foster the concept that design requirements should be generally incorporated into the Code merely because it is stated by some that the Code currently contains many design-related requirements. While it continues that there are numerous installations, which may require something, more than the minimum requirements of the NEC, it also continues to be the designer, not the NEC, who must determine if additional provisions are necessary for a safe installation.” And so the sides have been drawn over this historical Code provision. How do you view this question? Is 90-1, which has remained essentially unchanged in the Code for over 60 years, a founding precept upon which the Code rests? Is it one of the “bedrock principles that provides the Code’s public legitimacy,” as one national Code expert has stated? Should it remain unchanged and unquestioned? Or, should the section be deleted from the Code because CMPs have merely used it as a roadblock to the introduction of good, fundamental design criteria which impact safety and should therefore be in the Code? The answer most likely falls somewhere in between. Clearly, the Code is not a design specification and should not be used as such. Likewise, the Code is not a product specification, nor should it be. On the other hand, when “design” criteria is proposed into the Code, a careful analysis of the proposal should include considering how the proposal comports with the Code’s purpose. If the proposal enhances “practical safeguarding of persons and property,” additional latitude may be warranted, even where the proposal approaches “design” parameters. In either case, the burden of proof should be placed squarely on the submitter to demonstrate that the proposed text has discernable safety enhancements that override the possible design implications. As the 2002 NEC cycle unfolds, both electrical system designers and installers should weigh in on this important question to ensure that the 2002 NEC reflects and meets our industry’s needs. CALLANAN is director of Safety, Codes, & Standards at the National Joint Apprenticeship & Training Committee. He can be reached at

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