Article 708 of the National Electrical Code / NFPA 70
By Jeanne Murphy Murck, VP Operations
About the Author
Mission Critical…Critical Power… In our business, we have often heard these terms. Many advertise mission critical fuel oil systems that supply diesel to generator sets. The term has been used in the data center business for years. But what do these terms mean in a code-mandated context and how do they apply to you or your client’s facility?
A place to look is the National Electric Code. In 2008, Article 708 entitled “Critical Operations Power Systems” (COPS), was added to the NEC/NFPA 70. It was developed in response to natural disasters such as Hurricane Katrina and emergency events such as 9/11. This section includes the requirements for facilities that are truly defined and regulated as Mission Critical.
Mission Critical Sites
Mission critical sites are not just emergency systems as described in NEC Article 700 (or in NFPA 110 or NFPA 99). These are sites that have been formally classified by a municipal, state, federal or other authority having jurisdiction as critical because the facility must operate during the entire duration of an emergency event and beyond. Examples of facilities that can be classified as COPS or that may include Designated Critical Operations Areas (DCOAs) include police and fire stations, emergency operations centers, hospitals, various federal agency headquarters and federal data centers, and large airport air traffic control towers. These are the sites that, simply put, cannot lose power without affecting the security of the entire community.
Article 708 is unique in that it requires some things that previously would only have been considered best practices, including the following:
- It mandates designing COPS for DCOAs in accordance with a formal risk assessment of natural and man-made hazards and providing physical security and construction methods in accordance with that risk assessment (708.4-5).
- It requires routine testing and maintenance of COPS that is to be formally witnessed and/or documented by the local authority having jurisdiction (708.6).
- It discusses the options on power sources for COPS. For prime mover-driven generator sets, it necessitates dual supplies be provided for fuel or water (e.g., use of bi-fuel generators).
- It requires the COPS to have a minimum operating time of 72 hours with the DCOA at full load (708.22(C)).
How Core Engineered Solutions can Help you Comply
There are several key areas in complying with Article 708 that Core Engineered Solutions can help the design engineer or COPS end user address:
- Risk assessments and physical security (Sections 708.4 and 708.5) – ConVault fuel storage tanks are UL 752 and UL 2085 listed and provide unmatched protection from natural and man-made hazards.
- AHJ-witness and documented testing and maintenance (Section 708.6) – Core’s SafeSite line of fuel oil controls and advanced filtration systems allow a customer to fully and automatically test and maintain the fuel oil system components of a COPS.
- Power supply and alternate operating capability (Article 708.20 & 708.22) – Core can help size fuel oil tanks and system components, keeping in mind the maintenance and redundancy requirements found elsewhere in the Article.
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Glossary of Terms
Critical Operations Power Systems – Systems that are installed in vital infrastructure facilities that, if destroyed or incapacitated, would disrupt national security, the economy, public health or safety; and where enhanced electrical infrastructure for continuity of operation has been deemed necessary by governmental authority. COPS design criteria are specified by NFPA 70 Article 708.
Emergency Systems – As specified by NFPA 70 and NFPA 110, emergency systems are those systems legally required and classed as emergency by municipal, state, federal, or other codes, or by any governmental agency having jurisdiction. These systems are intended to automatically supply illumination, power, or both, to designated areas and equipment in the event of failure of the normal supply or in the event of accident to elements of a system intended to supply, distribute, and control power and illumination essential for safety to human life. See NFPA 70 Article 700, NFPA 110 Level 2.
Legally Required Standby Systems – Those systems required and so classed as legally required standby by municipal, state, federal, or other codes or by any governmental agency having jurisdiction. These systems are intended to automatically supply power to selected loads (other than those classed as emergency systems) in the event of failure of the normal source.
N+1 – A reliability term indicating that if a total of n units are installed, an additional unit is installed to ensure system reliability in the event of a single unit failure or to accommodate other activities such as periodic maintenance.
Optional Standby Systems – Those systems intended to supply power to public or private facilities or property where life safety does not depend on the performance of the system. Optional standby systems are intended to supply on-site generated power to selected loads either automatically or manually.