A new CNC line, a row of fleet chargers, a rooftop unit swap to heat pumps. Every one of those projects starts with the same question on a commercial building in San Jose: does the existing electrical service have room? The usual answer comes from adding up nameplates, and on a building that has been running for twenty years, that math often says no. The code offers a second route. You can measure what the building actually draws, and that number is frequently lower than anyone expected.

Why the nameplate math overstates a working building

A standard load calculation assumes equipment runs close to its rating. Real buildings rarely behave that way. Compressors cycle, machines sit idle between jobs, lighting has been retrofitted to LED since the original panel schedule was drawn, and half the receptacle circuits feed a monitor and a phone charger. The calculated load keeps counting all of it at full weight.

Getting the answer wrong in the cautious direction is expensive. A service upgrade means new switchgear, a utility application, and a wait on the utility's side of the work. PG&E reported that, as of March 1, 2026, it averaged 118 calendar days to finish its own steps after approving a new-service application. The state target is an average of 182 days. Switchgear lead times sit on top of that. If the service turns out to have room, all of that time and cost disappears from the project.

What the electrical code allows

California enforces the 2025 California Electrical Code, which took effect January 1, 2026 and is based on the 2023 National Electrical Code. Section 220.87 lets the existing load on a service or feeder be set by actual maximum demand in place of a calculated figure. It comes with three conditions:

  1. Real demand data. Either twelve months of maximum demand data, usually from the utility, or a continuous recording of at least 30 days. Maximum demand here means the highest average kilowatts held over a 15-minute interval.
  2. A 125% margin plus the new load. The recorded peak is multiplied by 125%. New continuous loads are added at 125% and noncontinuous loads at 100%. The total cannot exceed the ampacity of the feeder or the rating of the service.
  3. Proper protection. The feeder needs overcurrent protection under 240.4, and the service needs overload protection under 230.90.

The 30-day route has limits worth knowing up front. The recording has to be taken on the highest loaded phase while the building is occupied, and it has to account for the larger of the heating or cooling load along with any seasonal equipment. It is not permitted at all on a service with solar, wind, or any form of peak load shaving. A building with rooftop PV needs the twelve-month utility data or a standard calculation.

A load study replaces a guess about the building with a record of it. The plan reviewer gets numbers, and the owner gets an answer before ordering gear.

Check the utility data you may already have

PG&E account holders can download their interval usage history through the Green Button option in their online account. Twelve months of that data can satisfy the first condition without putting any equipment in your electrical room. You will need the account holder's login or written authorization, which slows things down on buildings where the tenant pays the bill.

Buildings in Santa Clara are served by Silicon Valley Power, the city's own utility, which runs its own records and service process. Our Santa Clara service page covers how that differs from PG&E work.

Utility data has two weak spots. It covers the whole meter, so it tells you nothing about a single feeder or a downstream distribution panel, and a year that included a long vacancy or a shutdown will understate the load. In either case a site recording is the better source.

How a 30-day recording works on site

A recording power meter goes on the service or feeder conductors inside the switchboard, and it is typically connected with the equipment energized so the business keeps running. That makes it live work in the electrical room, which calls for qualified electricians and arc-flash protective equipment. The meter logs demand on each phase, and the highest loaded phase is the one read against the code requirement.

Timing matters more than the hardware. The window should reflect a normal operating month, with no holiday shutdown and no half-staffed weeks. If the recording runs in spring and the building's peak is summer cooling, the cooling load gets added by calculation so the result reflects the worst month. The output is a record of peak 15-minute demand per phase, which translates into the existing load used in the calculation.

Here is how the math plays out, using round numbers for illustration. Say a 400A service records a peak equal to 220A on its highest loaded phase. At 125%, that becomes 275A of existing load. Adding a machine with a 60A continuous load counts as 75A, for a total of 350A. That fits under 400A, so the new machine can go in without a service upgrade. The same building might have failed a standard nameplate calculation.

When a study will not save the upgrade

Measuring helps most when the building has been over-provisioned on paper. It will not create capacity that is not there. A study is unlikely to change the outcome when:

  • The recorded peak already sits close to the service rating.
  • The new load is large relative to the service, such as a full electrification of heating or a fleet depot.
  • The service has solar or peak shaving and there is no twelve-month utility history.
  • The switchgear is at the end of its life, has no parts support, or has failed an inspection.

In those cases the study still earns its cost, because it gives the engineer and the utility a measured baseline for sizing the new service. The commercial panel upgrade checklist covers the sequence from there, and the three-phase panel upgrade page covers the 208V and 480V equipment we install.

Who asks for load studies

  • Manufacturers adding equipment. A new spindle or compressor on an existing floor is the classic case. It is a common question in machine shop electrical work.
  • Property managers planning EV charging. Parking lot chargers are continuous loads, so they count at 125% and eat margin quickly. Knowing the real headroom tells you how many ports the lot can support today.
  • Tenant improvement teams. A new tenant's equipment list may exceed what the suite's feeder was sized for. The tenant improvement team needs that answer before plan submittal.
  • Owners of multi-tenant buildings. A portfolio view of which buildings have room helps plan capital spending across several properties. It fits the way property management teams already plan work across a portfolio.

What drives the cost

The cost of a load study depends on how many services or feeders need recording, the voltage and access conditions in the electrical room, whether the meter can be installed during business hours, how long it stays on site, and whether the result goes into a permit submittal with an engineer's review. The cost of the work that follows depends on what the numbers show: a new circuit on an existing service is a very different job from new switchgear. For a quote on adding equipment to your building, call 408-630-0548 or fill out the quote form and we will set up a walk of the electrical room.

Frequently asked questions

  • What is an electrical load study?
    A load study records how much power a building or feeder actually draws over time. Under Section 220.87 of the electrical code, the result can set the existing load on a service in place of a calculation from equipment nameplates. It is used to decide whether new equipment fits on the existing service.
  • How long does a commercial load study take?
    The recording itself runs for at least 30 days, taken while the building is occupied and operating normally. If twelve months of utility demand data is available and usable, the analysis can be done without a site recording.
  • Can a load study help avoid a service upgrade?
    Often, yes. If the recorded peak at 125%, plus the new load, stays under the service rating, the new equipment can be added without upgrading. When the building is already close to its limit, the study instead gives a measured baseline for sizing the new service.
  • Can I use a 30-day load study if the building has solar?
    No. The code does not permit the 30-day recording method on a service with solar, wind, or any form of peak load shaving. Those buildings need twelve months of utility demand data or a standard load calculation.
  • How much does a load study cost in San Jose?
    It depends on how many services or feeders are recorded, access and voltage in the electrical room, whether the meter can be installed during business hours, how long it stays on site, and whether the report goes into a permit submittal. For a quote on the electrical work for new equipment, call 408-630-0548 or use the quote form on the contact page.

Planning new equipment on an existing service?

Send us the equipment list and the service size. We will walk the electrical room, check the service against what is going in, and send an itemized quote within one business day. Get an estimate or call the dispatcher to talk it through.