The 2017 NEC has a new article on energy storage systems, does UL List these systems?

Yes. UL Certifies/Lists energy storage systems for use in accordance with new Article 706 in the 2017 National Electrical Code (NEC)®.  UL Certifies/Lists these systems under the product category Energy Storage Systems and Equipment (FTBW).  Products certified under FTBW are investigated for compliance with UL 9540, Outline of Investigation for Energy Storage Systems and Equipment.  The UL guide information and Certifications/Listings for FTBW can be viewed on UL Product Spec at by entering FTBW at the category code search.  Presently, there is at least one Certification/Listing in this category.


Are panelboard circuit breaker interlock kits Listed as transfer switches to UL 1008?  Can they be used for optional standby systems such as with a portable generator?

Panelboard circuit breaker interlock kits are considered “transfer equipment” as permitted in NEC Section 702.5 and can be used in optional standby systems such as with portable generators. As transfer equipment, they are part of the panelboard and are investigated for compliance with ANSI/UL 67, the Standard for Safety for Panelboards. In contrast, transfer switches are evaluated to ANSI/UL 1008, the Standard for Safety for Transfer Switch Equipment.

Panelboard interlock kits are accessory kits and are often times mounted to the deadfront of a panelboard.  These kits may be factory- or field-installed when they are covered as part of the Certification/Listing of a panelboard and identified on the panelboard markings for use with a specific kit.  Because they are covered as an accessory to the Certified/Listed panelboard when identified, the field installed kits may bear the UL Recognized Component Mark.

NEC Section 702.5 Transfer Equipment states: “Transfer equipment shall be suitable for the intended use and designed and installed so as to prevent the inadvertent interconnection of normal and alternate sources of supply in any operation of the transfer equipment.” The guide information for the Panelboards (QEUY) product category addresses the suitability requirement in NEC 702.5 with the following statement: “Some panelboards, constructed with interlocked main switching and overcurrent protective devices, have been investigated for use in optional standby systems in accordance with Article 702 of the NEC and are marked ‘Suitable for use in accordance with Article 702 of the National Electrical Code ANSI/NFPA 70’, or, if provided within kit form, ‘Suitable for use in accordance with Article 702 of the National Electrical Code ANSI/NFPA 70 when provided with interlock kit Cat No. ____.’”

Manual transfer switches investigated for compliance with UL 1008, would be Certified/Listed under the product category Nonautomatic Transfer Switches (WPYV).

The guide information and Certifications/Listings for Panelboards (QEUY) and Nonautomatic Transfer Switches (WPYV) can be accessed on UL Product Spec at and enter QEUY or WPYV at the category code search.



Now that the 2017 NEC is published, will the installation code search on UL Product Spec be updated to include the 2017 NEC correlation?

Yes. The 2017 NEC correlation on UL Product Spec went live earlier this year.

UL Product Spec (, UL’s web compliance tool for the built environment, has been updated to include the correlation between the 2017 NEC Code sections and UL’s Certifications/Listings.

In UL Product Spec, just click on the installation code search, select “2017 NEC” and enter your code section.  UL Product Spec includes 20 model installation codes that have been correlated with UL’s Certifications/Listings.  Just pick a code and code section, and get a link to the Certified/Listed products complying with the code requirement.

Also, new in UL Product Spec is easy access to initiate a UL Field Evaluation.  In the lower right hand corner of the UL Product Spec screen is a link to “Request a Field Evaluation.” Click on the link and it will initiate an email to UL’s Field Evaluation staff to request a field evaluation.

For more information on UL Product Spec and to see YouTube videos on “How to Use UL Product Spec” go

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