What is the single most common reason a load calculation gets a plan-review comment?

Missing or underrepresented loads — most commonly HVAC equipment that changed after the original calculation, or new equipment (like EV charging) added later without updating the calculation. Cross-checking the calculation against the final, current equipment schedule before submission is the single highest-value check.

Do I need to show my work, or can I just submit the final calculated service size?

Showing category-by-category work with cited code sections and applied demand factors is strongly recommended — a calculation presenting only a final number forces the reviewer to either trust it blindly or request additional documentation, which slows down approval rather than speeding it up.

How do I know which code edition my jurisdiction has adopted for this project?

Confirm directly with the local building department before starting the calculation — jurisdictions adopt code editions on their own timeline, often lagging the newest published edition by a cycle or more, and this is one of the most common preventable sources of plan-review rejection.

Electrical·7 min read·August 14, 2026

📋 Common Plan-Review Errors in Electrical Load Calculations

The most frequent mistakes that generate plan-review comments on submitted load calculations — missing loads, misapplied demand factors, and documentation gaps that slow down permit approval.

By EngineersUniverse Editorial Team

Engineering Editorial & Technical Review Team

Published August 14, 2026

Why Load Calculations Generate So Many Plan-Review Comments

Load calculations are one of the most common sources of plan-review back-and-forth on electrical permit submissions — not because the underlying math is unusually hard, but because the calculation depends on correctly identifying every applicable load category, applying the right demand factor from the right code edition, and documenting the work clearly enough for a reviewer to verify it without having to reconstruct the designer's assumptions. Most rejected or commented-upon calculations fail on one of a fairly short, recurring list of issues.

Missing or Underrepresented Loads

The single most common error category: a load calculation that omits a piece of equipment entirely, or represents it at less than its actual rated value. Common culprits include: HVAC equipment sized from an outdated or preliminary spec rather than the actual selected/installed equipment; EV charging infrastructure added to a project after the original calculation without updating it; pool/spa equipment; and any equipment added during a later change order that never made it back into the load calculation. A plan reviewer comparing the load calculation against the full equipment schedule and one-line diagram will often catch a mismatch here quickly, so cross-checking the calculation against the actual current equipment list before submission avoids an easily preventable comment.

Misapplied Demand Factors

Applying a demand factor to a load category that doesn't actually qualify for it, using the wrong table (e.g., applying a residential demand factor structure to a commercial calculation, or vice versa), or using an outdated demand factor value from a prior code edition are all common technical errors. This is exactly why documenting which specific code edition and table each demand factor was pulled from (not just stating a final percentage) makes a calculation both easier to verify and easier to defend if questioned.

Continuous Load Factor Omitted or Misapplied

Forgetting to apply the 125% continuous-load multiplier where required (or applying it where it isn't required) is a common commercial-calculation error, since it's a separate consideration from demand factors and easy to overlook if a calculation template doesn't explicitly prompt for it.

Using the Wrong Code Edition

A calculation performed against an edition other than the one actually adopted by the jurisdiction reviewing the submission is a straightforward but recurring error, particularly on projects that span a jurisdiction's code-adoption transition or where a designer defaults to whatever edition their calculation software or habit uses rather than checking the specific project's governing edition. Always confirm the exact adopted edition before starting the calculation, not after a plan reviewer flags the discrepancy.

Insufficient Documentation to Verify the Calculation

A calculation that presents only a final total, without showing the category-by-category breakdown, the specific demand factors applied, and their code references, forces a reviewer to either trust it without verification or request the underlying work — the latter is a common source of review delay. A well-documented calculation shows its work at the same level of detail a reviewer would need to independently check it.

Mismatch Between the Load Calculation and the One-Line Diagram or Panel Schedule

The load calculation, one-line diagram, and panel schedule should all tell a consistent story about what's connected and how it's served — a discrepancy between the calculated service size and what's actually shown on the one-line or panel schedule is an easy, avoidable plan-review flag that a final cross-check before submission catches.

A Practical Pre-Submission Checklist

Cross-check every load category against the current, final equipment schedule — not a preliminary or outdated one.
Confirm the specific code edition being used matches what the jurisdiction has actually adopted.
Show category-by-category work with cited code sections/tables, not just a final total.
Verify the continuous-load 125% factor is correctly applied (or correctly not applied) per load category.
Cross-check the calculated service size against the one-line diagram and panel schedule for consistency.

Topics covered

plan review load calculation errorselectrical permit rejection reasonsload calculation mistakesplan reviewer comments electrical