Does an Electrical Panel Upgrade Need Title 24?
Not on its own. Section 150.2(b) lists every alteration Part 6 regulates in an existing house, and electrical service is not among them, so a panel swap needs an electrical permit and no Title 24 report. The panel rules in Part 6 are written for newly constructed homes.
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Why a panel swap triggers nothing
Section 150.2(b)1 runs from added windows through replacement systems, water heating, roofs, lighting and ventilation to exterior doors, and names no service, panel or busbar. The Section 100.1 definition of an alteration does mention the electrical power distribution system, but the definitions of service and service equipment apply to Section 130.5 only, which governs nonresidential buildings. The one other power rule, Section 110.11, certifies low-voltage transformers.
Where Part 6 does weigh panel capacity
Only in commercial work: replacing a single-zone rooftop unit under 65,000 Btu/hr follows Table 141.0-E-1 unless the alteration exceeds the existing main service panel or transformer capacity, shown by an engineer’s load calculation (Section 141.0(b)2Cii). See rooftop unit replacement.
New homes
Alterations get Sections 150.0(a) to (l), (m), (p) and (q); additions add (n). Sections 150.0(r) to (v) reach neither. So these belong to new construction:
- Battery ready, Section 150.0(s): service greater than 125 amps needs a 225-amp busbar, and a 200-amp panel qualifies only if its busbar is rated and marked 225. See JA12 battery storage.
- Solar ready, Section 110.10(e): a 200-amp busbar and a marked breaker space in a subdivision of ten or more without PV. See solar ready requirements.
- Electric ready, Section 150.0(n)1, (t), (u) and (v): reserved breaker spaces and 30 or 50-amp circuits where gas appliances go in. See electric-ready requirements.
When the question comes up
A heat pump. Part 6 sets no panel size, and replacing a gas furnace need not become a heat pump. The Energy Commission says most homes can fully electrify without upsizing, and that a panel may need it when existing circuits cannot carry the load, which is an electrician’s calculation. See heat pump requirements.
A detached ADU. It is new construction, so the rules above apply. Its subpanel can qualify through the main panel’s 225-amp busbar, and service of 125 amps or less is outside battery ready. HCD says it has no authority over electrical service.
An EV charger. Part 6 does not regulate it. CALGreen requires a raceway and panel capacity for a 40-ampere circuit in new houses; an existing house is an electrical job. See does an EV charger need Title 24.
Who decides the rest
Wiring follows the California Electrical Code, Part 3, and the building department sets the permit. If the panel is part of a remodel that replaces windows, ducts or a water heater, that work is regulated, and Section 10-103(a)1C lets a department waive or simplify the certificate for alterations needing no field verification.
Common Title 24 Questions
- When is Title 24 required for a home?
- Does a remodel need Title 24?
- Does a room addition need Title 24?
- What plans are needed for a residential Title 24 report?
- How much does a residential Title 24 report cost?
- How long does a residential Title 24 report take?
Frequently Asked Questions
Not for the panel alone. Section 150.2(b) lists no service, panel or busbar category for existing single-family buildings. The work needs an electrical permit under the California Electrical Code, and your building department decides how it is handled.
No. Section 150.0(s) applies to newly constructed one- and two-unit homes whose service is greater than 125 amps, and it is not among the sections that Section 150.2 extends to additions or alterations.
Only if its busbar is rated and marked at 225 amps. The Energy Commission says that without a specific busbar rating the panel rating is the busbar rating.
Part 6 sets no panel size for it. Whether the panel can carry the added load is a load-calculation question for your electrician and building department.
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View all Building Permit Questions guides → · Permits and Compliance · Title 24 guide