[RE-wrenches] Battery RSD

[William Miller]

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:mdelectricsolar at gmail.com]
*Sent:* Wednesday, July 30, 2025 12:33 PM
*To:* RE-wrenches
*Cc:* william at millersolar.com; 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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