Commercial panel and service upgrades

Voltage and phase come first

Every upgrade starts with what the building has and what the new equipment needs. Small commercial spaces are usually single-phase or three-phase at 120/208 volts. Larger buildings and heavy equipment often use 277/480-volt three-phase. The choice drives the panel, the breakers, the transformers and the price, and it cannot be swapped later without new gear.

Single-phase is fine for lights, outlets and small equipment. Motors, compressors, large kitchen equipment and DC fast chargers are the usual reasons to move to three-phase. LADWP’s service guide describes a Level III charger as typically 480 volts three-phase and treats its installation as equal to a commercial service installation or upgrade. If a landlord owns the building service, the landlord may need to approve the change.

What forces an upgrade

The usual triggers are a tenant improvement that adds kitchen or process equipment, a charger installation, a second floor of equipment, or a panel that has no spare breaker spaces. The tenant improvement page covers build-outs, and the restaurant and retail page covers the equipment-heavy case. Chargers are on the commercial EV charging page. A new LED system usually lowers load, so it rarely forces one. See the LED retrofit page.

The 2025 California Energy Code took effect January 1, 2026 for new buildings and major renovations. The Energy Commission says it replaces certain end-of-life rooftop HVAC units on stores, schools, offices and libraries with high-efficiency systems, including heat pumps, and sets electric-ready rules for commercial kitchens. Those can add electrical load. Ask the building department whether the change you plan pulls them in.

The load calculation

The load calculation is the paperwork that decides the size. It follows Article 220 of the electrical code, which sets how to add lighting, receptacle, motor and equipment loads. For a building that already runs, NEC 220.87 allows the electrician to use real demand instead of a calculated number, if conditions are met. One condition is one year of maximum demand data, which usually exists only as utility billing data. The other path is a load study of at least 30 days on the service, averaged over 15-minute periods, taken while the space is occupied. In both cases, 125 percent of the measured maximum plus the new load must not overload the service.

Ask the electrician which method is used and who supplies the numbers. The load calculation guide explains the home version.

Short-circuit rating and labels

Bigger services bring more fault current, which means breakers and panels must be rated for it. NEC 110.24 requires service equipment in non-dwelling occupancies to be field marked with the maximum available fault current and the date of the calculation. If a change raises the available fault current, the calculation and the marking are redone. Industrial installations with qualified-only maintenance are excepted.

NEC 110.16 covers a separate arc-flash warning label for equipment such as switchboards, panelboards, industrial control panels, meter socket enclosures and motor control centers in non-dwelling units that are likely to be worked on while energized. The label helps workers pick protective gear. The two labels are not the same thing.

How the utility side works

Each utility has its own request path, forms and lead times. LADWP’s guide says a commercial request needs the project address, a site plan, a one-line diagram showing service voltage and switch ratings, and a load schedule that names the air handling load and the largest motor. Then the steps run in order: the customer applies and pays fees, the Los Angeles Department of Building and Safety inspects and releases the meter, LADWP inspects the service equipment and energizes. LADWP does not publish a fixed time. It says completion depends on the complexity of the service and the number of services already scheduled. Underground work by the customer should finish 4 to 6 weeks before the building is complete, so cables and transformers can be installed.

SCE and SDG&E run similar request processes, but their commercial pages could not be opened during research on October 30, 2026, so this page states no step or time for them. The utility coordination guide covers who files what. A transformer or meter lead time is not stated here because none was found on a primary page.

Permit, plan check and inspection

Panel and service work needs a permit. A commercial job often goes to plan check with the one-line diagram and load schedule. Cities keep short lists for simple work. Long Beach allows an express electrical permit for replacing an existing service at the same ampere rating, wires, phase and location, up to 600 volts or 400 amps, and says that item does not cover upgrades. San Diego requires a permit for electrical work and has a no-plan track for nonresidential projects, with plans required outside it. The service and repair page lists the symptoms that lead to these jobs.

What to send

For a quote, send the building type, address, whether you are the tenant, owner or property manager, the current panel size and voltage, the new equipment list and what is planned, through the quote form. Photos of the panel label and the meter help.