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White Paper | Addendum to Some Codes and Standards Applicable to Stationary Batteries and their Chargers


A few months ago, we published a White Paper in our monthly newsletter titled “Some Codes and Standards Applicable to Stationary Batteries and their Chargers.” It was well-received and generated a lot of comments, and true to the sub-heading of “The great thing about codes and standards is that there are so many to choose from,” some readers wanted me to expand upon the subject and include some of the newer codes and standards, such as Underwriter’s Laboratories (UL) and U.S. Occupational Safety and Health (OSHA) documents. Well, rather than compose a whole new article, I’ve created an addendum to the original piece.

Addendum to Eagle Eye Power Solutions White Paper “Some Codes and Standards Applicable to Stationary Batteries and their Chargers.”

Underwriters Laboratories (UL) Documents Affecting Stationary Batteries and Chargers.

UL. Some background.

UL is probably the most recognized safety testing laboratory in the world. It began as an electrical and fire safety testing house that became a not-for-profit company, but has evolved, in recent years, moving into other safety issues such as safety and compliance education, hazardous materials, food and water safety, and performance testing. In 2012, UL became the parent company of a for-profit named UL LLC. This for-profit company handles the product certification and testing responsibilities.

UL is an accredited standards developer in the US and Canada. However, it is extending its global presence and UL Standards partners with national standards bodies in countries around the world to build a safer, more sustainable world.

There appears to be some misunderstanding as to the legal enforcement of UL standards and this is because of the use of the term “standards.” UL standards are compiled to aid in the safety and testing certification of products, and unlike other codes and standards, are not necessarily legally enforced or otherwise required by Authorities Having Jurisdiction (AHJ’s) or other federal, state, or local bodies. There is also some further confusion as to whether UL certification is required or not for products such as batteries and battery chargers. The short answer appears to be that it is required if the product plugs directly into an AC outlet; otherwise, it may be required if the manufacturer wants to obtain liability insurance or sell the product into a market that requires UL Listing.

What is the difference between UL Listed and UL Recognized?

Basically, a UL Listed product is a stand-alone, fully functional product or assembly that has been fully tested to UL safety standards. It will include such things as fire and electrical safety. These products carry a distinctive seal, sometimes referred to as the UL Mark, that indicates that the product has met the stringent UL testing standards.

UL Recognition applies to individual components in a product but not the complete end product or system. An example may be a sub-assembly such as a power supply or a printed circuit board. It is easier to obtain a UL Recognition mark. Often, this option is used by a manufacturer whose product doesn’t meet the full UL certification requirements. A good example is the UL Recognition of battery flame arresting vents.

Therefore, a UL Recognition can apply to any component part or materials. If the UL logo is to be used on a stand-alone product, that product must be tested as a whole assembly and obtain the UL Listing.

Some UL Documents Affecting Stationary Batteries and Chargers.

UL 94

The UL 94 Standard provides a method for rating the flammability characteristics of plastic materials. Two UL 94 ratings that code officials commonly run across are HB and V (V-0, V-1, or V-2). This is typically used for battery case and cover materials.

UL 924

This Standard applies to emergency lighting and power equipment for use in unclassified locations and intended for connection to branch circuits of 600 volts or less. Such equipment is intended to automatically supply illumination or power or both to critical areas and equipment in the event of failure of the normal supply, in accordance with Chapter 7 of the National Electrical Code, NFPA 70, the Life Safety Code, NFPA 101, the Fire Code, NFPA 1, the International Building Code (IBC), and the International Fire Code (IFC).

UL 1012.

This is the UL Standard for Safety of Power Units other than Class 2. These requirements cover portable, stationary, and fixed power units having an input rating of 600 volts or less, DC and AC current, with at least one output not marked Class 2, and that are intended to be employed in ordinary locations in accordance with the National Electrical Code, NFPA 70.

UL 1236.

These requirements cover battery chargers rated 600 volts or less and intended for household or commercial use to charge lead-acid engine-starter and other starting, lighting, and ignition (SLI) type batteries, in accordance with the National Electrical Code, NFPA 70. 

UL 1778

These requirements cover Uninterruptible Power S (UPS) rated 600 volts or less AC or DC that are intended for installation in accordance with the National Electrical Code, NFPA 70. During normal operation, periods of power fluctuations, or power outages, or both, where the connected load receives AC power from the battery supply and power conversion portion of the UPS. Battery cabinets, with or without batteries are covered by this standard.

UL 1973.

This covers batteries for use in stationary and motive auxiliary power applications. ANSI/CAN/UL 1973 addresses lead-acid batteries through an evaluation program added to the Standard, which provides an alternative approach to evaluating valve-regulated or vented lead-acid or nickel-cadmium batteries for stationary applications. These requirements cover battery systems as defined by this standard for use as energy storage for stationary applications such as for PV, wind turbine storage or for UPS, etc. applications. These systems must be installed in accordance with NFPA 70, Canadian Electrical Code C22.1, or other applicable installation codes.

UL 1989

The requirements of UL 1989 cover valve-regulated or vented batteries that can be used as instrument batteries, enclosed batteries, emergency lighting and power batteries and UPS batteries. Also, a battery system composed of vented, or valve regulated types with battery management controls and other battery system components. These requirements only address potential risks unique to the use of a battery supply in a product. These requirements are intended to address aqueous electrolyte valve-regulated or vented batteries such as lead-acid, nickel-metal hydride, nickel-zinc, or nickel-cadmium, etc., and do not cover risks that may be unique to certain cell chemistries, such as the fire and explosion risks of lithium batteries. Lithium batteries are outside the scope of this standard.

UL 9540 and UL 9540A

UL 9540 is a safety standard for an Energy Storage System (ESS) and equipment intended for connection to a local utility grid or stand-alone application. It designates key issues associated with ESS, including functional safety, battery system safety, fire detection, suppression, containment,and environmental performance. The standard aim is to assess the safety and compatibility of each part of the ESS. This standard does not cover ESS’s that use lead-acid or nickel-cadmium batteries.

UL 9540A, the Standard for Test Method for Evaluating Thermal Runaway Fire Propagation in Battery ESS’s, on the other hand, as the name implies, is a test method for evaluating thermal runaway propagation for battery ESS’s. It will not provide UL certification but rather, it provides data for manufacturers to see if their product meets the regulations. Various US codes such as NFPA 70, the international Fire Code, and NFPA 855, the Standard for Installation of Stationary Energy Storage Systems.


Are UL standards mandatory? Well, UL Standards are often voluntary, however, several Authorities Having Jurisdiction (AHJ’s) and electrical, fire and residential codes may require a UL listing on products and systems.

Almost all manufacturers of battery and related products claim some sort of UL compliance but sometimes this can be misleading. Such terms as “meeting UL requirements” or “complies with UL” are often used but that doesn’t necessarily mean that the product has been safety tested by UL or other recognized testing laboratory. Up until recently, many manufacturers of traditional lead-acid and nickel-cadmium products did not deem it necessary to have their products UL listed although some did use UL 1989.

There are many other standards, codes, practices, and guides pertaining to battery and peripheral equipment which are not covered in this technical note. Tune in within the next few months when we will address OSHA, European CE marking, the Code of Federal Regulations, and other requirements which may be pertinent to batteries and peripheral equipment.

UL Standards can be obtained directly from UL in several ways:

Online: https://www.shopulstandards.com/

Phone: +1-415-352-2168

Fax: 1-630-274-6338:

Mail: Comm 2000, 151 Eastern Avenue, Bensenville, IL 60106

Further Reading:

Florence, Laurie.UL1973 appendix H: a new safety approach to traditional lead acid and nickel cadmium stationary battery systems. Proceedings of Battcon 2021.

Miraldi, Andrew K. UL9540A large scale fire testing results for sodium nickel chloride batteries used in stationary ESS applications. Proceedings of Battcon, 2021.

Schubert, Randy, Kludge, Richard. Use of UL Standards in NFPA 855-2009. Proceedings of Battcon 2019.

McDowell, Jim. Compliance with codes and standards relating to lithium-ion batteries: a manufacturer’s perspective. Proceedings of Battcon 2021.

Florence, Laurie. Stationary Battery Standards: Current Landscape and What’s Coming Soon. Proceedings of Battcon 2014.

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