National Electrical Code ExplanationsBased on the 2014 NEC
National Electrical Code Tips: Article 708, Critical Operations Power Systems (COPS)
Chapter 7 of the NEC starts off with a series of five Articles about onsite power generation systems: 700, 701, 702, 705, and 708. These aren't sequential (several that would be in the sequence aren't there, for example 706) and there's not another Article until Article 708. The reason for this is Chapter 7 is relatively new in the NEC and it's intended to cover "future conditions" we have not yet thought of.
Let's address some
highlights of the Article 708 requirements:
- Article 708 deals with critical operations power systems. What the heck are those? First of all, understand this is not a general term. An area is officially designated as critical, and thus becomes a Designated Critical Operations Area (DCOS). The power system for such an area is classed as such by the government agency (municipal, state, federal) and that agency's codes if such agency has jurisdiction (it usually does). The system may also be classed as a DCOS by facility engineering documentation that establishes such a system is needed [708.1].
- COPS include, but aren't limited to, general power systems, HVAC, fire alarm, security, and communications systems for the DCOS [780.1].
- What are the rationale for designating an area as a COPS? These systems are typically installed in vital infrastructure facilities that, if incapacitated, would disrupt national security, the economy, or public safety. So you can't say, "Gee, we need to declare this area of our manufacturing plant a DCOS because if it goes dark that would be a critical problem for us." It has to be a critical problem of national scope. So you could say that if your plant manufactures something essential to, say, national security. See Informational Note 1 under 708.1.
- Risk assessment is, er, critical for COPS. It must be documented. It must identify the particular hazards and provide a mitigation strategy for them [708.4].
- The electrical systems of COPS must be made secure by restricted access. Based on the risk assessment additional physical security (e.g., armed guards) must be provided [780.5]. If you're doing electrical work in COPS, of course you're not providing this security. But you will be interacting with it. Ensure all of your people understand and follow the rules.
- Testing and maintenance are not afterthoughts for COPS. First, the system must meet commissioning requirements that include component and system tests, baseline maintenance testing, and functional performance testing [708.8]. Before going operational, the system must be witness tested. Once operational, it must undergo witness testing periodically (by AHJ). Additional testing must be done by the maintenance department, per industry standards and practices [708.6].
- Keep the wiring separate from that of other systems. Ensure the receptacles are readily identifiable as COPS receptacles, and all boxes and enclosures are readily identified as being part of the COPS [708.10].
- The COPS cannot rely on the normal power supply alone. You must also provide, in case of normal power supply failure, at least one of the specific backup power sources identified in 708.20(E) through (H).
- Branch circuits supplied by the COPS can supply only equipment required for critical operations use. If management wants other loads also backed up, they'll need to come up with the money (and space) to install a separate backup system [708.30].
- The OCPDs of COPS must be selectively coordinated with all supply-side OCPDs. The selective coordination must be done by a licensed PE or other qualified person [708.54].
How the NEC is arranged
- The first four Chapters of the NEC apply to all installations.
- Article 90 precedes Chapter One, and establishes the authority of the NEC.
- Article 80 follows the body of the NEC; it exists as Annex H. It provides the requirements for administration.
- Chapters 5, 6, and 7 are the "special" chapters, covering special: occupancies, equipment, and conditions (in that order).
- Chapter 8 provides the requirements for communications systems.
- Chapter 9 provides tables.
- The appendices provide mostly reference information.
- Appendix D contains examples that every NEC user should study.
Try your NEC moxy:
- Do you know the difference between bonding and grounding? Hint: Look in the NEC, Article 100.
- Does the NEC refer to grounding incorrectly in any of its articles? Yes! So be careful to apply the Article 100 definitions. Don't ground where you should bond.
- When doing motor load calculations, which Article covers hermetic motors? Answer: While Article 440 covers the application of hermetic motors, it does so only by amending Article 430 because hermetic motors are a special case of motors. For motor load calculations, refer to Article 430.
- Does the NEC provide a voltage drop requirement? Yes! It does so in a special case, which is Article 648 Sensitive Electronic Equipment. But for general applications, it does not provide a requirement; it merely provides a recommendation in a couple of FPNs.
- Take our Code Quizzes.
Remember other applicable codes, rules, standards, and references:
- OSHA's electrical worker safety rules.
- IEEE standards.
- NETA standards.
- NFPA standards.
- International Codes (if applicable to the installation).
- State Codes (if the state has them).
- Local ordinances and permit requirements.
- Local fire codes.
- Manufacturer requirements or guidelines.
- Customer security requirements.
- Industry standards.
- Your company's own internal standards, practices, and procedures.
- Engineering drawing notes.
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