When Should a Commercial Facility Have an Electrical Load Study?

Separate calculated load, measured demand and equipment rating

These terms answer different questions:

• Calculated load: the load established using the applicable electrical-code calculation method, including the relevant equipment and permitted factors.
• Measured demand: the load recorded at a defined point during a defined period and interval.
• Equipment rating: the documented capability of the service, conductors and distribution equipment, subject to its application and installation conditions.

The rating on a main breaker is not a measurement of current building use. Spare breaker spaces are not proof of spare electrical capacity. A review must connect the demand information to the actual system that will supply the added equipment. Fluke distinguishes calculating or measuring existing loads from checking equipment and conductor capacity.

Where a study can help owners make decisions

• Property management: establish an electrical basis for a prospective tenant's requirements before finalizing improvement allowances.
• Manufacturing: evaluate a proposed machine or process expansion before purchasing equipment with a fixed delivery date.
• Restaurants: review a revised kitchen schedule while the layout and equipment selections are still being coordinated.
• Facilities: compare current operation with planned HVAC, lighting or occupancy changes.
• EV charging: include the number of chargers, charging power and intended operating schedule in the capacity discussion.

These are planning examples, not a claim that every project requires the same monitoring exercise. Ask the electrical designer or contractor which calculation or measurement approach is suitable, what documentation the permit authority expects and whether utility coordination is needed.

A utility bill is useful, but read the right data

Electricity consumption, expressed in kilowatt-hours, measures energy used over time. Demand, expressed in kilowatts, describes the rate of use over a measurement interval. A monthly energy total alone does not show the peak demand. SDG&E explains consumption and demand.

Interval data provides a more detailed picture than monthly totals and can reveal when a building uses power. The National Laboratory of the Rockies explains load profiles and interval data. Ask the project team whether the available records cover the right meter, time period and portion of the facility. A whole-building record may not answer a question about a particular tenant feeder.

Provide information about vacancies, shutdowns, seasonal operation and recent equipment changes. Identify solar, storage or other systems that may affect what a utility meter records. Those details help the reviewer decide whether historical data represents the operation being proposed.

Agree on the monitoring period before it starts

Do not assume that a short site visit—or a standard month-long recorder rental—automatically produces an acceptable permit study. The purpose of the study, accepted calculation method, available history and operating conditions matter.

Fluke's application guidance discusses occupied-building measurements, seasonal loads and local review requirements. It references an older NEC edition, so its duration discussion should not be treated as a universal current California rule. Read the application note's scope and assumptions. Have the project team confirm the adopted code and documentation expectations before collecting data, and document operating conditions during the recording period.

What the report should help you decide

Ask for an understandable report that identifies the monitored equipment, measurement dates, recorded peaks, operating assumptions and proposed additions. It should explain the applicable calculation approach, relevant system limitations and any information still needed before a design decision.

Request a conclusion tied to your project: can the existing distribution support the planned work, is a feeder change needed, or should a larger service be investigated? Also ask whether separate short-circuit, protection-coordination or other engineering analysis is needed; a demand chart alone does not answer every electrical-design question.

A building capacity review also does not reserve utility capacity. SCE provides a separate process for new loads and service upgrades. Coordinate with the utility serving the actual property; some Southern California locations have a different provider. SCE's power request and upgrade guidance explains its process.

What to prepare for the first conversation

Gather available electrical drawings, panel schedules, utility bills and interval records, plus the proposed equipment schedule. Include voltage and phase requirements from the supplier, planned hours of operation, expansion dates and any shutdown restrictions. Let the electrical team obtain information that requires opening or accessing electrical equipment.

Tell the team which decision is most urgent: signing a lease, ordering equipment, pricing a tenant improvement or planning a service upgrade. Halo's Power & Utility Upgrades page shows related installation work. If the immediate issue is repeated tripping or unreliable power, discuss it through Pro Care service; a future capacity study should not postpone troubleshooting an active problem.