Michael/Wrenches:
I am glad to hear this was resolved. I don’t think this is the last we will hear about this issue. Whether you are calling the system an “ESS” or a “battery”, disconnecting means are usually required. This is specified in Section 480 for batteries and Section 706 for ESS. The proliferation of stationary batteries in our world is new and building officials and integrators are still learning the rules. Any building inspector or plan checker could stand their ground on this issue and insist a disconnect be installed. A high-current, load-break DC disconnect is not a simple or inexpensive item. My contracts have a clause that states if additional requirements are presented by a regulating agency the client is required to pay for the work to provide compliance. This is meant to cover additional permitting work or installation of equipment required by new regulations. This means I don’t get hurt complying-- the customer does. Added costs just make it harder to install these systems that are beneficial to the user and the environment. As is often the case, the industry is behind the curve with this issue: BMS-equipped battery systems should provide a contact-closure-triggered inhibit function. If the BMS has an on/off button it should be able to retrofit it with a remote trigger for that function. Similarly, manufacturers of BOS equipment could provide a lockout ring on the battery breaker that should satisfy the requirement. I hope the 250 amp shunt-trip breaker can acquire listing soon. Know that any changes in listed systems require a lot of expensive testing but if disconnecting means are added to any future update that requires testing anyways, that cost is absorbed in the process. William Miller PS: In my opinion it was a mistake to call this an “RSD” issue. Rapid Shutdown is a specific term associated with PV only in Section 690.12. Wm Miller Solar 17395 Oak Road, Atascadero, CA 93422 805-438-5600 www.millersolar.com CA Lic. 773985 *From:* MDElectricSolar [mailto:[email protected]] *Sent:* Wednesday, July 30, 2025 12:33 PM *To:* RE-wrenches *Cc:* [email protected]; Jason Szumlanski; RE-wrenches *Subject:* Re: [RE-wrenches] Battery RSD I emailed and eventually spoke with the building inspector supervisor and got him to agree that what they're looking for is an AC disconnect, within sight of the ESS which disconnects and locks open any connection to the house. He was going to reiterate to his inspectors that it is not between the battery and the inverter. Michael D Nelson MD Electric & Solar, Inc.
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