706.15 Disconnecting Means.
Code Change Summary: New emergency shutdown requirements for an ESS in one- and two-family dwellings.
In the 2023 NEC®, the rules pertaining to disconnecting an energy storage system (ESS) were revised and restructured and the previous language providing ESS disconnecting requirements for one- and two-family dwellings has been modified to require ESS emergency shutdown.
The revised 2023 language in 706.15 requires a means to disconnect an ESS from all wiring systems, including other power systems, utilization equipment, and its associated premises wiring.
Section 706.15(B) provides rules on location and control of the disconnecting means and provides three options to choose from, all of which require the disconnecting means to be readily accessible:
Option (1) A disconnecting means located within the ESS
Option (2) A disconnecting means located within sight and within 10 feet from the ESS
Option (3) For a disconnecting means not located within sight of the ESS, the disconnecting means, or the enclosure providing access to the disconnecting means, shall be capable of being locked in accordance with 110.25
For one- and two-family dwellings, an ESS must now include an emergency shutdown function to cease the export of power from the ESS to the premises wiring of other systems. An initiation device must be located where readily accessible outside the building and must plainly indicate whether in the "on" or "off" position. Switching the device to the "off" position must perform the ESS emergency shutdown function.
Below is a preview of the NEC®. See the actual NEC® text at NFPA.ORG for the complete code section. Once there, click on their link to free access to the 2023 NEC® edition of NFPA 70.
2020 Code Language:
706.15(A) ESS Disconnecting Means. A disconnecting means shall be provided for all ungrounded conductors derived from an ESS and shall be permitted to be integral to listed ESS equipment. The disconnecting means shall comply with all of the following:
(1) The disconnecting means shall be readily accessible.
(2) The disconnecting means shall be located within sight of the ESS. Where it is impractical to install the disconnecting means within sight of the ESS, the disconnect shall be installed as close as practicable, and the location of the disconnecting means shall be field marked on or immediately adjacent to the ESS. The marking shall be of sufficient durability to withstand the environment involved and shall not be handwritten.
(3) The disconnecting means shall be lockable open in accordance with 110.25.
For one-family and two-family dwellings, a disconnecting means or its remote control shall be located at a readily accessible location outside the building.
2023 Code Language:
706.15 Disconnecting Means.
(A) ESS Disconnecting Means. Means shall be provided to disconnect the ESS from all wiring systems, including other power systems, utilization equipment, and its associated premises wiring.
N (B) Location and Control. The disconnecting means shall be readily accessible and shall comply with one or more of the following:
(1) Located within the ESS
(2) Located within sight and within 10 feet from the ESS
(3) Where not located within sight of the ESS, the disconnecting means, or the enclosure providing access to the disconnecting means, shall be capable of being locked in accordance with 110.25
Where controls to activate the disconnecting means of an ESS are used and are not located within sight of the ESS, the disconnecting means shall be lockable in accordance with 110.25, and the location of the controls shall be marked on the disconnecting means.
For one- and two-family dwellings, an ESS shall include an emergency shutdown function to cease the export of power from the ESS to premises wiring of other systems. An initiation device(s) shall be located at a readily accessible location outside the building and shall plainly indicate whether in the "off" or "on" position. The "off" position of the device(s) shall perform the ESS emergency shutdown function.