Planning an all-electric home: load, panel capacity and code

Adding an EV charger, a heat pump, a heat-pump water heater or an induction range raises how much electricity you buy and how much your service must be able to deliver. Those are two different problems, and conflating them is why so many homeowners are told they need a service upgrade before anyone has measured anything.

A panel upgrade is sometimes genuinely necessary. But California’s electrical code contains more than one legitimate route to adding load, and at least one of them starts by measuring what your home actually draws rather than adding up nameplate ratings.

You cannot add up nameplate amps and call the result a demand forecast. Nameplate is what a device can draw; the code contains calculation methods precisely because real households never run everything at once. Any tool or salesperson that sums nameplate ratings and concludes you need an upgrade has skipped the actual question.

The 2025 California Electrical Code (Title 24, Part 3), based on the 2023 National Electrical Code, took effect January 1, 2026, replacing the 2022 edition. If you are reading guidance written against the older cycle, section numbers and requirements may have moved. The California Building Standards Commission publishes the current codes at dgs.ca.gov/bsc/codes, and local jurisdictions such as LADBS may add amendments.

Three routes exist for adding load to an existing dwelling. Article 220.83 provides an optional calculation for adding loads, with separate treatment depending on whether air-conditioning or electric heating is being added. Article 220.87 allows the calculation to be based on your actual metered maximum demand — real interval data from the utility rather than assumptions, which frequently demonstrates that an existing service has room. Load management equipment, covered by the articles governing EV supply equipment and energy management systems, prevents large loads from running simultaneously so they can share existing capacity.

Which route your jurisdiction accepts is the authority having jurisdiction’s call. That is a question for a licensed electrician who works in your city, not for an article.

• Service size — the rating of the main service, usually 100 A, 125 A or 200 A.
• Main breaker rating, which is not always the same number as the service.
• Panel busbar rating, printed on the label inside the panel door.
• Recent maximum demand — interval data from your utility account, the input the measured-demand route needs.
• Existing electric heating, if any, and what it serves.
• What you are adding, with nameplate ratings: EV charger, heat pump, heat-pump water heater, induction range, dryer.
• Existing large loads — pool or spa equipment, well pump, workshop.
• Any solar or battery already installed, and its interconnection method.
• Planned work — an ADU or addition changes the answer, so mention it even if it is a year away.

Panel upgrade or service upgrade?

They are different jobs with different costs. A panel upgrade replaces the load centre — the busbar and breakers. A service upgrade changes the supply itself: the meter, the service entrance conductors, and sometimes utility-side equipment. You can need one without the other, and the utility is only involved in the second.

100 amp or 200 amp?

200 A is the modern default for new construction, and it comfortably accommodates several new loads. But 100 A service is not automatically disqualifying — whether it works depends on your calculated load, your measured demand, and whether load management is used. That is a calculation, not a rule of thumb.

Load calculation or load study?

A load calculation applies the code’s method to your specific loads on paper. A load study measures what the home actually draws over time. The measured-demand route in the code exists precisely so that real data can replace conservative assumptions.

What is load management?

Equipment that prevents two large loads from drawing at once — typically pausing EV charging while another heavy appliance runs. It lets loads share existing capacity instead of requiring more of it, and the code recognises it. For solar-specific busbar questions, that is a different rule; see do you need a main panel upgrade for solar.

Does solar or a battery add service capacity?

No. This is a common and expensive misunderstanding. Solar reduces the energy you buy; a battery shifts when you buy it. Neither increases what your service can deliver at a moment in time, and both have their own interconnection rules that can themselves consume busbar headroom.

1. Establish what you have — service size, main breaker, busbar rating.
2. Pull your interval data from the utility, so the measured-demand route is available.
3. List what you are adding, with nameplate ratings and realistic timing.
4. Have a licensed electrician run the calculation under the applicable code method.
5. Ask about load management before accepting an upgrade — it is often cheaper than one.
6. Ask the utility about upstream capacity, which is theirs to answer, not your electrician’s.
7. Upgrade only if the accepted routes do not produce the capacity you need.

For LADWP customers there is a concrete step most homeowners miss. LADWP advises contacting an Electric Service Representative at least two weeks before installing a home charging station. The ESR assesses service capacity up to the meter — whether LADWP needs to change a transformer or the lines to the house — while your electrician handles everything past it. LADWP states an ESR will schedule a site visit within five to ten business days. Commercial, public and multi-family charging require plans, and 480-volt (Level III) stations are handled by a Service Planning Engineer. Source: LADWP Guide to Electric Service, March 2024.

Doing this early is the difference between a scheduling detail and a project stalled for weeks waiting on utility-side work.

Every added kilowatt-hour is a kilowatt-hour your solar array has to cover if you want to keep the same offset. Electrifying without resizing simply moves you from a well-covered bill to a partly-covered one.

The rate structure matters too. In SCE territory under the Net Billing Tariff, exported energy is worth less than energy you use yourself, so added evening load — EV charging, heat pumps — strengthens the case for a battery. LADWP’s retail-basis netting treats daytime export more generously. The right answer differs by utility, which is why a national rule of thumb is not much help in Los Angeles.

This page explains the framework. It deliberately does not publish per-appliance kilowatt-hour figures or an amperage verdict, because credible numbers require manufacturer and federal appliance data and a climate-specific model for heating — work we have not finished and will not fake.

Nothing here is a service load calculation. A licensed C-10 electrician must perform the calculation for your specific panel, service and jurisdiction before any work is designed or permitted.

Figures on this page come from the primary sources below and, where noted, from Cali Energy calculations using the stated assumptions. Rates, incentives, and program terms change; each was verified August 11, 2026.

1. California Building Standards Commission — current codes
2. LADWP — Guide to Electric Service (March 2024)