Which code applies
The 2025 California Electrical Code, Title 24 Part 3, is based on the 2023 NEC and took effect on 1 January 2026. California adopts the NEC through its own code rather than directly, with state amendments, so the edition in force is set by the state code cycle and not by the NFPA's publication date.
That puts California on the 2023 NEC's numbering. The measured-load method is section 220.87, and it is cited as 220.87 on a California submittal. The 2026 NEC renumbers the same method to 120.87, and that number does not apply in California until the state adopts the 2026 edition through a future code cycle.
Who may sign the calculation
In California, anyone who practices or offers to practice electrical engineering must be licensed by the Board for Professional Engineers, Land Surveyors, and Geologists. Electrical engineering is one of the three practice-act disciplines in the state, with civil and mechanical, which means the practice itself is licensed and not only the title.
A licensed contractor may design electrical systems, in accordance with the applicable codes, for work it will install and supervise itself within its licence classification. The section does not allow a contractor to design work that somebody else will install. So a C-10 contractor calculating the load for a service it is upgrading itself is within the statute. A calculation prepared for a permit somebody else will build, or one an authority asks to be sealed, needs a licensed electrical engineer.
Whether a given permit application needs a seal is the authority's rule inside that statute, and it differs between cities. Ask the authority that will review the permit before submitting.
What the utility does with a service upgrade
Service line extensions and upgrades run under Electric Rule 16; distribution line extensions under Rule 15. Service line extensions run under SCE's Rule 16. A New Service Request goes to SDG&E's Construction Services group with site plans, load data and the licensed contractor's details. The rule is a CPUC electric tariff rule and it is the same rule at all three.
PG&E's own roadmap for a panel upgrade runs: planning and application through its Your Projects Portal, a load assessment it describes as taking up to 30 days, then a fork. If the infrastructure supports the new load, the job goes straight to disconnect and reconnect. If it does not, PG&E designs and estimates the infrastructure work, the customer signs and pays, and PG&E builds it before reconnection.
PG&E asks applicants to submit the load evaluation request as soon as they have project details or a building permit, to outline every electrical load need including panel size and voltage, and to upload photographs of the existing service and a panel cut sheet. A sealed load study is that outline, with the existing load established by measurement rather than assumed, and it is the document that decides which side of PG&E's fork the project lands on.
What is adding load in California
The 2025 CALGreen code, effective 1 January 2026, sets the number of EV-capable spaces and installed chargers for nonresidential parking by parking count in Table 5.106.5.3.1, and raises the installed share for occupancies other than office and retail to half of the EV-capable spaces.
Bay Area Air District Rules 9-4 and 9-6 require zero-NOx appliances at replacement: water heaters under 75,000 BTU per hour from 1 January 2027, space-heating furnaces from 1 January 2029, and water heaters from 75,000 BTU per hour up to 2 million from 1 January 2031. The district was considering amendments to the 2027 date during 2025. Each of those replacements is a heat pump, and a heat pump is electrical load on a service that was sized for gas.
The Advanced Clean Fleets rule's private-fleet provisions were withdrawn in January 2025 and are being repealed. The provisions for state and local government fleets stand: half of vehicle purchases zero-emission in 2025 and 2026, and all of them from 2027.
What a load study changes here
The standard calculation under Article 220 assumes far more of a facility's equipment runs at once than ever does, and on an operating facility it lands high. Section 220.87 allows the existing load to be established from what the service actually drew: the maximum demand over 12 months of utility records, or over a 30-day recording where those are not available, taken at 125% and added to the new load against the rating.
On the utility side, that measured figure is the load information the application asks for. Where it shows the existing service carries the new load, the project goes to the short side of the fork. Where it does not, the upgrade application starts with a documented existing load rather than an assumed one. Either way it is the same sealed document, and either way it was worth having before the application went in.
Questions people ask
Is California on NEC 2023 or NEC 2026?
The 2025 California Electrical Code, Title 24 Part 3, is based on the 2023 NEC and took effect on 1 January 2026. The 2026 NEC does not apply in California until the state adopts it through a later code cycle.
Can my electrical contractor do the load calculation?
A licensed contractor may design electrical systems, in accordance with the applicable codes, for work it will install and supervise itself within its licence classification. The section does not allow a contractor to design work that somebody else will install. If the authority requires the calculation to be sealed, or somebody other than that contractor will install the work, it needs a licensed electrical engineer.
How long does PG&E take?
PG&E describes its load assessment step as taking up to 30 days and says the overall time varies with the project's complexity and the number of requests it has. That is PG&E's own description of its own process, and it is the only figure this page will quote for it.
Does a load study go to the utility or to the city?
Both can ask for it. The authority having jurisdiction reviews the permit and may require the calculation to be sealed. The utility reviews the load information on a service application. One sealed study serves both.