A new tenant signs a lease. Their build-out plan calls for a commercial kitchen, a server room, or a fleet of EV chargers in the parking lot. Everyone assumes the building's electrical system can absorb it. Often, it can't.
Tenant finish delays are rarely about the drywall or the flooring. They're about power. And by the time an undersized electrical service shows up as a problem, it's usually mid-construction, which is the most expensive point in the project to discover it.
Every commercial building has an electrical service rated in amps, typically 200A, 400A, 800A, or higher depending on square footage and use type. That number is fixed unless a utility upgrade is scoped and paid for. Before any tenant finish drawings get approved, the first question should be: how much of that service is already spoken for by existing tenants, base building systems, and code-required reserve capacity?
Most buildings don't run anywhere near their electrical service rating on day one. Capacity gets consumed over time, lease by lease, tenant by tenant, until an owner discovers there's nothing left for the next build-out.
An electrical load calculation adds up every circuit a new tenant's design will draw, HVAC, lighting, equipment, receptacles, and compares that total against what the building's service and distribution equipment can actually deliver. This is different from an architect's mechanical or electrical narrative. It's a hard number, tied to code (NEC Article 220 governs load calculations), that tells you whether the existing infrastructure supports the new design or whether something upstream needs to change.
Three outcomes come out of that calculation: the building has capacity and the tenant finish proceeds on the existing service and panels; the building is close to capacity and load management, demand response, or panel upgrades close the gap without a full utility service upgrade; or the building is over capacity and a utility service upgrade is required, which involves the utility company, longer lead times, and real cost that needs to be built into the deal before construction starts, not after.
A few patterns show up repeatedly in older commercial buildings and multi-tenant properties: the panel schedule shows most breakers already allocated, even if actual usage looks lower; previous tenant finishes added subpanels or feeder taps without updating the building's as-built electrical documents, so nobody has an accurate picture of total draw; and the building was built or last upgraded more than 20 years ago, before modern HVAC, IT, and equipment loads were typical for that use type.
Any of these should trigger a load study before tenant finish design goes further, not after construction documents are already at permit.
An electrical capacity problem discovered during permitting or construction turns into a change order, a delayed opening, and a tenant relationship strained before they've even moved in. Discovered during lease negotiation, it's a line item that gets priced, scheduled, and either passed through to the tenant or absorbed by the owner as a known cost of doing the deal.
Property owners who ask for an electrical capacity assessment before signing a lease with aggressive power requirements protect their timeline and their tenant relationship. It's a short exercise relative to the cost of finding out the hard way.
If you're evaluating a tenant finish and don't have a clear answer on remaining electrical capacity, that's the first thing to get in writing before design moves forward.
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