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National Electrical Code Articles and Information

Based on the 2017 NEC

by Mark Lamendola

National Electrical Code Top Ten Tips: Article 517 -- Healthcare Facilities

  1. Article 517 also applies to medical care facilities. In fact, it was originally written and has been subsequently revised with medical care facilities, not health care facilities, in mind.

    The Code-making Panels simply got their English wrong. See the incorrect definition of "health care facilities" in 517.2. Note that this describes medical care facilities, but health care facilities may also come under Article 517.

    Since preventive dental care occurs in a dental office, a dental office is a health care facility that is specifically mentioned in Article 517. As your guide, assume that if the facility has "patients" then it's covered by Article 517.
  2. Grounding is a distinguishing focus of Article 517. You will find references to this time and again, throughout Article 517.
  3. All branch circuits serving patient care areas must have an effective ground fault path [517.13(A)].
  4. A distinguishing aspect of medical care and health care electrical installations is that receptacles have specific grounding requirements. You will find these (and fixed electrical equipment grounding requirements) in 517.13.
  5. You must keep metallic objects bonded, to prevent flashover and other problems. For example, 517.14 requires that you bond the panelboards and related equipment.
  6. Ground fault protection is held to a higher standard than normal, in medical care and health care facilities. Refer to the selectivity requirements stated in 517.17(C).
  7. There are different requirements for general care areas [517.18], critical care areas [517.19], and wet procedure areas [517.20].
  8. The largest Part of Article 517 is Part III: Essential Electrical System. This provides the requirements for a system capable of supplying a limited amount of lighting and power service essential for life safety and orderly cessation of procedures in the event of loss of normal power.
  9. While communications and signaling is normally the purvey of Chapter 8, for medical care and health care facilities there are additional requirements in Article 517, Part VI.
  10. An isolated power system is one comprising an isolating transformer (or equivalent), a line isolation monitor, and its ungrounded circuit conductors [517.2]. The requirements for such systems are in Article 517, Part VII.

How the NEC is arranged

  1. The first four Chapters of the NEC apply to all installations.
  2. Article 90 precedes Chapter One, and establishes the authority of the NEC.
  3. Article 80 follows the body of the NEC; it exists as Annex H. It provides the requirements for administration.
  4. Chapters 5, 6, and 7 are the "special" chapters, covering special: occupancies, equipment, and conditions (in that order).
  5. Chapter 8 provides the requirements for communications systems.
  6. Chapter 9 provides tables.
  7. The appendices provide mostly reference information.
  8. 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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