California battery-ready rules for new homes

What the code requires

Section 706.10 is a California-only section from the Energy Commission; it is not in the national code. It requires each dwelling unit in a single-family building with one or two dwellings to get the dedicated raceways, designated branch circuits, isolation devices and minimum panel busbar rating spelled out in Energy Code section 150.0(s). The alternative is an installed energy storage system.

Under the 2025 Energy Code, 150.0(s) applies to new single-family buildings with one or two dwelling units whose utility service is greater than 125 A. The builder must provide either battery-ready interconnection equipment with at least 60 A of backed-up capacity and at least four battery-supplied branch circuits, or a raceway of at least 1 in. trade size from the main service to a subpanel labeled to hold all the backed-up load circuits.

At least four branch circuits must be identified and grouped in one panelboard suitable to be fed by a battery. They must include the refrigerator, a lighting circuit near the primary exit, and a receptacle outlet in a bedroom. The main panelboard busbar must be rated at least 225 A. Space must be reserved within 3 ft of the main panel for future isolation equipment or a transfer switch, with raceways installed between the two.

On the job

• A main panel with a 200 A busbar on a covered new home does not meet the 225 A minimum.
• A missing 1 in. raceway (where battery-ready interconnection equipment is not used), a missing subpanel label, or no reserved transfer-switch space within 3 ft of the main panel each fails the requirement.
• These rules are for new construction; the Energy Code lists them as not applicable to additions and alterations.
• The over-125 A service trigger, the exception for homes with a battery installed and the BESS (battery energy storage system) wording are new in the 2025 Energy Code; the 2022 version did not have them.

Exceptions that matter

• A home that has a battery storage system installed is exempt from the readiness requirements.

In California

The 2025 CEC text of 706.10 still uses the older energy storage system wording and mentions a minimal backup capacity, while the 2025 Energy Code exception sets no capacity minimum; treat Energy Code 150.0(s) as controlling and confirm with your building department.

Related sections

• NEC 705.12: The 120% rule for solar and battery breakers
• NEC 408.2(B)
• NEC 422.3: California: electric-ready water heater, cooktop, dryer
• NEC 440.3: California: heat-pump-ready circuit at gas furnaces
• NEC 702.4: Sizing whole-home generators and backup batteries

Where this comes from

• California Building Standards Commission: 2025 California Electrical Code amendments (rev. 2025-11-20)
• California Energy Commission: 2025 Building Energy Efficiency Standards (CEC-400-2025-010-F), 150.0(s)
• California Energy Commission: What's New for 2025 Single-Family (rev. 2/19/25)
• California Energy Commission: 2022 Building Energy Efficiency Standards, 150.0(s)
• Read the official NEC free at NFPA