Does my ADU need 240V electric-ready circuits if I install gas appliances?

If it is a new detached ADU, yes. The California Energy Commission's 2025 ADU FAQ says the electric-ready requirements in Energy Code Sections 150.0(n) and 150.0(t) through (v) apply to newly constructed detached ADUs that use gas or propane for water heating, space heating, cooking or clothes drying. Attached ADUs and garage conversions are treated as additions, and the Commission's electric-ready guidance says these provisions do not apply to additions or alterations.

What each gas appliance triggers

• Gas furnace, 150.0(t): a dedicated 240-volt branch circuit within 3 feet of the furnace, conductors rated at least 30 amps, a blank cover marked "240V ready," and a reserved double-pole breaker space in the main panel marked "For Future 240V use."
• Gas cooktop, 150.0(u): the same arrangement within 3 feet of the cooktop, with conductors rated at least 50 amps.
• Gas dryer, 150.0(v): the same arrangement within 3 feet of the dryer location, with conductors rated at least 30 amps.
• Gas water heater, 150.0(n): a designated space at least 2.5 by 2.5 feet and 7 feet tall for a future heat pump water heater. If that space is within 3 feet of the water heater, you need a dedicated 125-volt, 20-amp receptacle fed by a 120/240-volt, three-conductor branch circuit rated at least 30 amps, with the unused conductor labeled "spare," plus a reserved single-pole breaker space labeled "Future 240V Use." If the space is farther away, you need a dedicated 240-volt circuit rated at least 30 amps within 3 feet of the space, a reserved double-pole breaker space, and the hot and cold piping routed through the space. Either way, a condensate drain no more than 2 inches above the base of the water heater is required.

Where the electrical code comes in

California amends its electrical code to match. Sections 408.2(B), 422.3 and 440.3 of the 2025 California Electrical Code require the breaker spaces, circuits and labeling the Energy Code specifies, in single-family buildings with one or two dwellings.

Local gas rules

Some California cities have adopted local rules that limit or discourage gas in new construction. Check yours before you design gas piping, because the answer may be an all-electric ADU instead.

Load and panel planning

Reserved spaces and readiness circuits are easy to include while the walls are open and hard to add later. Your designer decides how future electric appliances are treated in the load calculation, but planning panel space and capacity for them now helps avoid a forced upgrade when a gas appliance is later replaced with a heat pump or induction unit.

What this means for your electrical plan

The panel schedule should show each reserved space and its label, the floor plan should show each 240V-ready outlet location and the designated heat pump water heater space, and the Title 24 report should match. See all-electric rules and ADU electrical planning, gas line requirements and our ADU Title 24 guide.

Sources: energy.ca.gov, energy.ca.gov, energy.ca.gov, dgs.ca.gov.