Article 90.5 of the National Electrical Code (NEC) clarifies the types of rules and material included in the Code, helping users understand what is enforceable and what is provided for guidance.
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Article 90.5: Mandatory Rules, Permissive Rules, and Explanatory Material
(A) Mandatory Rules
- Definition: Mandatory rules specify actions that are explicitly required or prohibited.
- Language: These rules are characterized by the use of the terms «shall» or «shall not».
- Purpose: They establish enforceable requirements to ensure safety and compliance.
(B) Permissive Rules
- Definition: Permissive rules describe actions that are allowed but not required.
- Language: These rules are characterized by the use of the terms «shall be permitted» or «shall not be required».
- Purpose: They provide flexibility by allowing options or alternative methods for compliance.
(C) Explanatory Material
- Definition: Explanatory material includes additional information to help users understand the Code.
- Formats:
- Informational notes: Provide context, references to other standards, or related sections of the Code.
- Informative annexes: Offer non-enforceable guidance.
- Key Details:
- References to other standards are considered latest editions unless a specific date is included.
- Bracketed references to other NFPA documents are informational only and indicate the source of extracted text.
- Enforceability: Explanatory material is not enforceable as a requirement of the Code.
(D) Informative Annexes
- Definition: Informative annexes provide nonmandatory information related to the use of the NEC.
- Purpose: They offer additional guidance and context but are not part of the enforceable requirements.
- Examples: Annexes may include best practices, historical information, or supplemental explanations.
Summary of NEC Article 90.5
| Section | Description |
|---|---|
| (A) Mandatory Rules | Enforceable rules using «shall» or «shall not» to specify required or prohibited actions. |
| (B) Permissive Rules | Non-enforceable rules using «shall be permitted» or «shall not be required» to allow optional methods. |
| (C) Explanatory Material | Informational notes and references to other standards or sections, not enforceable. |
| (D) Informative Annexes | Nonmandatory guidance included for informational purposes only. |
Why This Matters
Article 90.5 helps users distinguish between enforceable requirements and informational guidance in the NEC. This clarity ensures proper application of the Code while allowing flexibility and innovation in electrical installations.