Code reference · NEC 706 (disconnecting means and marking); verify exact subsection numbering against your adopted edition
NEC 706: battery energy storage disconnects
Article 706 applies to energy storage systems above 50 V or 1 kWh (jurisdictional adoption varies — verify locally). The core requirement: a readily accessible disconnecting means for all ungrounded conductors between the ESS and the premises wiring, with the disconnect either within sight of the ESS or capable of being locked open.
The disconnect must be marked with nominal ESS voltage, maximum available short-circuit current, and the associated arc-flash/date marking where required.
Practical pairing: size the ESS output circuit conductors at 125% of the continuous output rating, and check the OCPD interrupt rating (AIC) against the available fault current — large LiFePO4 banks routinely exceed cheap fuse AIC ratings.
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