How does California's all-electric mandate affect ADU electrical planning?

California's electrification push — driven by a growing list of local all-electric reach codes plus a Title 24 energy code that strongly favors heat pumps — reshapes ADU electrical design by moving loads that used to live on a gas line onto the electrical panel. The practical result is larger panels, more dedicated circuits, and a more carefully run load calculation.

What "all-electric" changes

Many California cities have adopted ordinances that restrict or prohibit gas appliances in new construction, including ADUs. When gas is off the table, every major appliance becomes an electrical load:

• Induction range / cooktop: 40–50A dedicated circuit (vs. zero panel load for a gas range).
• Heat pump space conditioning (mini-split): 15–30A depending on capacity.
• Heat pump water heater: 20–30A.
• Electric or heat-pump dryer: a dedicated circuit.

Together these can add 80–120 amps of connected load compared with a gas-appliance equivalent — which is exactly why all-electric ADUs trend toward 125–200 amp panels.

The downstream planning effects

1. Panel sizing. The Article 220 load calculation must account for all of these electric loads at once, often pushing past what a 100A subpanel can carry.
2. Service capacity. A heavier ADU load makes a main-house service upgrade more likely, especially on older 100A services.
3. Circuit count. More dedicated appliance circuits means a panel with adequate breaker spaces — another reason to favor 125A over 100A.
4. Coordination with mechanical and Title 24. Heat pump selection drives both the mechanical plans and the Title 24 report, so these disciplines need to agree on equipment.

Plan even if your city still allows gas

Even where gas remains legal, the 2025 California Energy Code makes all-electric designs the path of least resistance for compliance, and many owners choose them to future-proof against tightening rules. If you go all-electric voluntarily, size the panel as though it's mandated — you'll avoid an expensive upgrade later.

Requirements vary by jurisdiction and utility, and reach codes change frequently — confirm current rules with your local building department before finalizing electrical or mechanical system design.

Our full MEP package coordinates electrical panel sizing with heat pump selection and Title 24 so the all-electric design holds together across disciplines.