Ensuring ESS Safety in Data Centers with NFPA 855 – Part 1

March 31, 2021
ZincFive paper on how the NFPA 855 standards helps ensure ESS safety

As data centers expand in size and number, so will the demand for sufficient, reliable and safe backup power. UPS battery systems will get larger and distributed more widely, which will heighten scrutiny on potential hazards from all that stored energy.

In this first post in a two-part series, we’ll provide an overview of the latest regulatory requirements needed to meet regional fire codes and maximize safety, including the latest guiding document on the topic, NFPA 855.

More data centers + more power density = more potential risk

Gartner projects that the total annual spend on data center infrastructure will surpass $200 billion in 2021, representing a 6% rise over 2020. Uninterruptible power supply (UPS) systems play an increasingly critical role within the expanding data center architecture, maintaining operations should a power outage occur anywhere in the network.

In addition, increasing demands for Energy Storage System (ESS) power density have driven migration towards more dense battery chemistries, especially lithium-ion. The combination of higher power requirements and new technology can raise the risk of situations where thermal runaway and fire becomes a threat to staff and first responders, as well as to the services that depend on the data center’s servers and storage.

Data center operators, managers and engineers need to be familiar with the alphabet soup of regulatory requirements that help to operate their facilities safely. Fortunately, they now have one relatively new standard, NFPA 855, as the guiding document.

Meet the fire safety organizations

Both the National Fire Protection Association (NFPA) and the International Codes Council (ICC) periodically update their regulatory standards/codes relating to fire safety. Every authority having jurisdiction (AHJ) across North America will reference these, relying on either the NFPA 1 National Fire Code or the ICC’s International Fire Code.

To support the standards/codes published by these organizations, Underwriters Laboratories (UL) have defined stringent testing standards through which system safety can be verified. Among the ones that data center operators need to be most aware of are these:

  •  UL 1778, which directly relates to UPS;
  •  UL 1989 which pertains to standby batteries;
  •  UL 2054 which pertains to household and commercial batteries;
  •  UL 1643 which addresses lithium-ion technology in particular;
  •  UL 1973 which considers the electronic safety system accompanying the ESS;
  •  UL 9540, which covers both grid-connected as well as standalone systems; and
  •  UL 9540A test methodology by which thermal runaway is assessed.

To add yet another layer of complexity, recommended best practices produced by the Institute of Electrical and Electronics Engineers (IEEE) serve to inform the UL standards. These cover the various different battery chemistries that could be used in ESS deployments: IEEE 1187/8/9 for valve-regulated lead-acid, IEEE 1679.1 for lithium-ion selection, IEEE 1679.4 for aqueous alkaline chemistries, and IEEE 1105/15 for nickel-cadmium batteries. Though these are guidelines, and consequently do not have the legislative weight of the documents published by the NFPA or ICC, they are very important from an insurance perspective.

With dramatic increases in ESS deployment activity in the coming years—for renewable energy storage as well as for data center back-up—the industry has needed greater clarity on how to assess ESS safety. Those implementing an ESS have needed a fully coherent regulatory framework to organize the alphabet soup described above and simplify the way forward.

NFPA 855 is shaping up to be that framework.

NFPA 855 unifies ESS testing criteria

After several years in development, the NFPA published the NFPA 855 standard at the start of 2020. The principal objective of NFPA 855 is to bring together all the numerous criteria involved in ESS fire safety under one unifying standard.

The NFPA 855 standard sets out the installation safety rules to which an ESS must adhere. To ensure the ongoing safety of their ESS installations, data center operators should have a strong understanding of this new standard, covering all of the key aspects. UL 1778, UL 1973, UL 9540 and UL 9540A testing procedures are all cited within the document. IFC -2021 and the latest revision of the NFPA 1 National Fire Code, which are both due to be published later this year, will reference or parallel the requirements of NFPA 855.

IFC -2021 and the upcoming revision of the NFPA 1 National Fire Code will reference or parallel the requirements of NFPA 855.

In the second post in this two-part series , we’ll explain more about what NFPA 855 is and how to use it.

Dan Lambert, ZincFive Codes & Standards Specialist
Dan Lambert
Senior Product Manager, ZincFive
Dan has over 40 years of commercial and industrial electrical experience and has worked with AC and DC power systems, with a primary focus on mission-critical power systems. Working with stationary battery systems since 1985, Dan has worked with many battery chemistries and has contributed to large scale energy storage analysis projects, as well as testing other storage systems. Dan is currently a member of the IEEE Power and Energy Society serving as the chairperson for the IEEE Energy Storage and Stationary Battery Committee’s IEEE 1679.4 Alkaline Chemistries Working Group and is a member of the Battcon conference Technical Committee.