A reusable structure for documenting an NEC load calculation clearly enough for plan review — sections, what to include in each, and why documentation format affects how quickly a calculation gets approved.
Why Documentation Format Matters as Much as the Math
Two load calculations with identical, correct arithmetic can have very different plan-review outcomes depending on how clearly the work is documented — a calculation a reviewer can verify at a glance moves through review faster than one requiring back-and-forth to reconstruct the designer's assumptions. This template structures a load calculation report so the essential information — what's included, what code edition and tables were used, and how each number was derived — is immediately visible.
Section 1 — Project and Code Basis
State the project name/address, service voltage and configuration (e.g., 240V single-phase, 480Y/277V three-phase), the specific NEC edition being used, and any local amendments applicable to load calculation methodology. This section answers "what are we calculating and against what code basis" before any numbers appear.
Section 2 — Load Category Summary Table
A table listing every load category included in the calculation (general lighting, receptacles, fixed appliances, HVAC, EV charging, and any others specific to the project), with columns for: connected load (VA), applicable demand factor, demand load (VA), and the specific NEC section/table reference the demand factor was pulled from. This is the core of the report — a reviewer should be able to verify each row independently against the cited code section.
Section 3 — Calculation Method Statement
Explicitly state which Article 220 calculation method is being used (standard method, or the optional method where applicable for dwelling units) — this matters because the two methods use genuinely different demand factor structures, and a reviewer needs to know which one to check the numbers against.
Section 4 — Total Demand Load and Required Service Size
Sum of all demand loads from Section 2, converted to amperes at the project's service voltage, with the resulting required minimum service size and the actual specified/installed service size shown side by side — making explicit that the specified service meets or exceeds the calculated minimum, not just stating the specified size in isolation.
Section 5 — Assumptions and Exclusions
Note any significant assumptions made (e.g., "HVAC equipment per manufacturer spec sheet dated [date]; EV charging calculated assuming EVEMS configured to cap aggregate demand at [X] VA") and any loads deliberately excluded with justification (e.g., a future-use circuit not yet connected to equipment). This section is what lets a reviewer understand the calculation's scope without guessing.
Section 6 — Future Load Provisions (Optional but Recommended)
If the design includes headroom for anticipated future load (a spare breaker space reserved for a future EV charger, for example), note it explicitly — this demonstrates the design was deliberate about future capacity rather than leaving a reviewer to wonder whether unused capacity was intentional or an oversight.
Keeping the Template Reusable
Build this structure as a reusable template (spreadsheet or document format) rather than starting from scratch on every project — the section structure stays constant across projects even as the specific load categories and values change, and a consistent format also makes internal QA review faster for firms checking each other's calculations before submission.