517.30 Sources of Power.
Code Change Summary: Requirements for power sources serving the essential electrical system have been revised.
The rules for two sources of power serving the essential electrical system have been removed from 517.35, revised and relocated to 517.30. Along with the relocation were deletions of some of the performance requirements in Article 517
As stated in 90.2, the NEC® is an installation code. Article 517 previously contained many performance requirements which were better left to remain in NFPA 99. It only makes sense that if the NEC® is an installation code, requirements for the design and performance of health care facility electrical systems should be removed from Article 517 and code users should be directed to the appropriate NFPA design and performance documents.
The relocated and revised text covers the power source requirements for health care facilities with an essential electrical system (EES). The general rule is to make sure the EES is supplied by two independent sources of power. This is usually accomplished by normal utility power and an emergency generator but new subsection 517.30(B)(2) provides rules on using fuel cell systems as the alternate power source for an EES.
Fuel cell systems consume fuel to produce electric current. They generate power from electro-chemical reactions that take place within the fuel cell. These systems are highly reliable and provide additional options for health care facility power design.
Below is a preview of the NEC®. See the actual NEC® text at NFPA.ORG for the complete code section. Once there, click on their link to free access to the 2017 NEC® edition of NFPA 70.
2014 Code Language:
517.35 Sources of Power.
(A) Two Independent Sources of Power. Essential electrical systems shall have a minimum of two independent sources of power: a normal source generally supplying the entire electrical system and one or more alternate sources for use when the normal source is interrupted.
2017 Code Language:
517.30 Sources of Power.
(A) Two Independent Power Sources. Essential electrical systems shall have a minimum of the following two independent sources of power: a normal source generally supplying the entire electrical system and one or more alternate source(s) for use when the normal source is interrupted.
(B) Types of Power Sources.
(1) Generating Units. Where the normal source consists of generating units on the premises, the alternate source shall be either another generating set or an external utility service.
N (2) Fuel Cell Systems. Fuel cell systems shall be permitted to serve as the alternate source for all or part of an essential electrical system, provided the following conditions apply: (See NEC® for remaining text)
(C) Location of Essential Electrical System Components. Essential electrical system components shall be located to minimize interruptions caused by natural forces common to the area (e.g., storms, floods, earthquakes, or hazards created by adjoining structures or activities). Installations of electrical services shall be located to reduce possible interruption of normal electrical services resulting from similar causes as well as possible disruption of normal electrical service due to internal wiring and equipment failures. (See NEC® for remaining text)