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Energy storage system installations: residential occupancies – Code File, April 2024

May 5, 2024 | By Nansy Hanna, P.Eng.

May 5, 2024 – Energy storage system (ESS) installations are growing. Consider that, in addition to smaller ESS installations that serve local communities, businesses, and homes, the Independent Electricity System Operator expects to have at least 1217 MW of storage capacity participating in Ontario’s electricity market by 2026.

Recognizing this rapidly evolving and expanding technology, the recently published 2024 CE Code-Part I includes three new subsections (under Section 64) with crucial updates for ESSs: one subsection applies to all ESSs in general terms; one covers ESSs that utilize batteries; and the third applies to the installation of ESSs at residential occupancies.

Let’s look at some of the notable changes that apply to residential occupancies:

Previous Rule 64-918 “Location and separation requirements for ESS” has been deleted and and replaced with:
• New Rule 64-1100 that provides location and separation requirements for ESSs at residential occupancies.
• New Rule 64-926 that provides requirements for separation and egress from buildings for all installations.

The previous Rule 64-918 did not permit ESS installations in dwelling units, which severely curtailed broader adoption of the technology. (Note: “dwelling unit” can be a single dwelling unit, or a dwelling unit in a rowhouse, duplex, triplex, or stacked quadruplex.)


The CE Code-Part I (2024) now permits these installations. The ESS is to be located in an attached garage, an associated detached garage, or other freestanding structure; on the exterior surface of the building; in a dedicated (e.g. utility) room following certain specifications; or in other locations permitted by the authority having jurisdiction.

When an ESS is installed in a dedicated room, a smoke alarm or detector shall be installed in the room in accordance with Section 32.

The same requirements and permissions apply to an ESS installed in a building containing multiple dwelling units; however, the room in which the ESS is located must have a fire resistance rating of not less than one (1) hour.

It is important to note the new rules provide capacity limitations for a single system and, where multiple systems are installed, limitations have been set for the aggregate capacity. (Although the previous CE Code also had capacity limitations, the 2024 edition increases them in some locations.)

Some of the requirements for dwelling units have not changed. For example, ESSs shall not be installed in sleeping areas or rooms opening directly into sleeping areas, and smoke alarms or detectors must still be installed in the room in which the system is located.

This new subsection was developed by a task force that included a diverse representation of manufacturers, regulatory bodies, installers, and certification bodies. They diligently reviewed challenges and concerns from the field, with the overarching goal of aligning the CE Code with UL 9540 “Energy storage systems and equipment”.

The CE Code 2024 contains additional requirements that are important to review before planning or designing new energy storage system installations, and I will explore them in future columns.

Nansy Hanna, P.Eng., is senior director, Engineering & Regulations, at Ontario’s Electrical Safety Authority (ESA). She is also chair of the Canadian Advisory Council on Electrical Safety (CACES) and a member of the ULC Advisory Council and CSA Technical Committee on CE Code-Part I.

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