Electrical Capacity and Load Studies

Adding production equipment, building out a tenant space, expanding a facility, or electrifying a gas load all raise the same question: can the existing electrical system support the new load?

A capacity assessment answers that with calculations, not assumptions: whether the service has room, which equipment limits the addition, and what upgrades may be needed, before equipment is ordered or a utility application is submitted.

How We Determine Your Existing Load

We review the building's actual demand, calculate the proposed additions, and check the affected service, transformers, feeders, and panels against the combined load.

Where the adopted code edition permits it and the records represent normal operation, measured demand can establish existing load more accurately than a sum of nameplates. Where the data falls short, we say so and identify what else is needed. Calculation details are in the FAQ below.

Account for What Is Being Added, Removed, or Relocated

A facility expansion does not always mean every existing load stays in place. Older chillers may be removed when a central cooling system is installed. Compressed-air requirements may change. New production equipment may receive a new service while nearby HVAC equipment is connected to an existing one.

We identify which loads will remain, which will be permanently disconnected, and which will move to another service or feeder. That helps establish the proposed loading at each affected connection point.

Utility records also need to match the equipment being evaluated. A bill or demand summary covering multiple services may not establish the demand on an individual service. We confirm what each meter measures and identify where separate records or field monitoring are needed.

Any allowance for removed equipment needs a documented basis under the applicable calculation method. We do not simply subtract its nameplate rating from a historical demand peak. Equipment already disconnected during the recorded period must not be credited again.

Non-Simultaneous and Standby Loads

Not every installed load operates at the same time. Duty and standby pumps, backup compressors, or equipment serving alternate processes may have different operating arrangements. We evaluate which loads can run together, including automatic starts, testing, and changeover conditions.

Where the applicable code permits an allowance for non-simultaneous operation, we document the operating arrangement and any interlocks or controls needed to support it. Standby equipment is not automatically excluded from the load calculation.

What the Core Assessment Includes

• Existing maximum demand from utility records or other available demand data
• Proposed load calculation, including continuous and motor loads per the applicable NEC articles
• Service conductors, main overcurrent device, and switchboard or switchgear bus ratings
• Transformer loading and remaining capacity
• Each feeder and panelboard that serves the new load
• Verification of removed, relocated, non-simultaneous, and standby loads
• Voltage drop at the proposed equipment
• Available spaces, poles, and breaker positions
• Identification of changes that may require further fault current, coordination, or arc flash review

Additional Services When Needed

These are included only when the project requires them and are identified in the proposal:

• On-site demand recording where utility records are unavailable or not representative
• Detailed load flow modeling
• Motor starting analysis for large motors or demanding starting conditions
• A separate short circuit study, protective device coordination study, or arc flash study update

Common Capacity Constraints

The service may have capacity while a downstream panel does not. Capacity at the main does not establish capacity at the point of connection. A feeder, transformer, or panel serving the new equipment may be the limit.

Kilowatt demand alone may not establish current loading. Without kVA or power factor data, current calculated from kW demand can be understated. We request that data and note when the records cannot support a conclusion.

Utility capacity can be a separate constraint. Your equipment may carry the load while the utility transformer or service cannot. Utility upgrades can involve long lead times, so this should be identified early.

Electrical upgrades may affect existing arc flash results. Transformer, conductor, or protective device changes, including a utility transformer change, can alter available fault current and clearing time. We identify which ratings and arc flash results need review. See why a utility upgrade can make your arc flash labels wrong.

When You Need One

• Adding production equipment or a new process line
• Tenant fit-out, building addition, or change of occupancy
• EV charging, or electrifying equipment that previously ran on gas
• Replacing or consolidating equipment, or installing standby equipment
• Before submitting a service application to the utility
• Confirming that the existing system supports a design prepared by others
• Independently verifying a recommendation that you need a service upgrade

What You Get

A report prepared under the responsible charge of a licensed Professional Engineer, including:

• Existing demand and proposed-load calculations
• Capacity findings for the affected distribution equipment
• Identification of limiting equipment and recommended upgrades
• Assumptions, missing information, and limitations
• Drawing updates and sealing as identified in the proposal and required by the jurisdiction

Can the Assessment Be Completed Remotely?

Reliable one-line drawings, demand records, panel schedules, equipment nameplate information, and clear photographs of the service equipment may support remote work. Missing or conflicting information may require field verification, which the proposal identifies.

Frequently Asked Questions

How does NEC 220.87 use existing demand data?

Where the adopted code edition includes this method and its conditions are met, NEC 220.87 permits the existing load to be based on twelve months of maximum demand data. That maximum demand at 125 percent, plus the calculated new load, must not exceed the ampacity of the feeder or the rating of the service. We confirm the adopted edition and the conditions that apply to your installation.

What if twelve months of data is not available?

Where the applicable code permits a shorter recording period, it must meet the method's conditions. These include a minimum thirty-day recording period, fifteen-minute demand intervals, representative occupied operation, and accounting for the larger heating or cooling load and other seasonal or periodic loads.

When might recorded demand not represent the load?

Solar generation, energy storage, peak shaving, or low production can affect whether recorded demand represents the load being evaluated. A low-demand period is not automatically a suitable basis for a capacity conclusion.

How is the new load treated?

We calculate the proposed load separately using the applicable code requirements and permitted demand factors. We do not subtract a utility peak from the main breaker rating or assume new equipment will be idle during the existing peak.