Load Calculation Permit: What a Plan Checker Actually Wants to See

The panel says 200A" is not a load calc. I hear a version of that sentence on almost every panel upgrade job that comes back red-lined, and it's the single most common reason a load calculation permit package gets rejected.

Here's what a plan checker is actually looking for, why the nameplate rating doesn't cut it, and how to get the load calc right the first time.

Why Load Calcs Get Red-Lined

A load calculation isn't a summary of what equipment is installed. It's a demand calculation — a documented, code-referenced method showing that the connected load, once you apply the right demand factors, fits inside the service or panel you're proposing.

The most common mistakes I see on rejected packages:

Panel rating used as the load calc. Contractors submit "200A panel installed" and call it done. The AHJ doesn't care what the panel is rated for — they want to see the calculated demand load and confirmation it's within that rating.

Adding up breaker sizes. Summing every breaker in the panel produces a number way higher than the actual demand load, and it's not how NEC Article 220 works. Breaker ratings protect conductors; they don't represent connected load.

No code reference. A load calc without a cited method (standard or optional, Article 220 Part III or IV) reads as unsubstantiated to a plan checker. They need to see the math tied to a specific NEC section.

Missing existing loads. On a panel upgrade or added-load job (EV charger, generator, heat pump), the calc has to account for what's already on the panel — not just the new equipment. Plan checkers catch this immediately.

Standard Method vs. Optional Method (Article 220)

NEC Article 220 gives you two ways to calculate a dwelling's load, and which one applies depends on the job.

Standard method (Part III) is the general-purpose calculation. General lighting load, small appliance and laundry circuits, fixed appliances, HVAC (larger of heating or cooling), and demand factors applied in sequence. This is the method most plan checkers default to expecting unless the optional method clearly applies.

Optional method (Part IV) simplifies things for single-family dwellings and existing dwellings with specific conditions — it applies a flat demand factor to the general load after the first 10 kVA, which usually produces a lower calculated demand than the standard method. It's faster to run and often favorable for panel upgrade and added-load scenarios, but it only applies under the conditions Article 220 specifies (dwelling unit, single feeder, etc.) — using it where it doesn't apply is its own rejection reason.

For commercial and mixed-use work, neither dwelling method applies — you're into Article 220 Part III general demand factors or occupancy-specific calculations, which is its own conversation.

The point: which method applies isn't optional in the sense of "pick whichever gives a lower number." It's determined by the type of building and the scope of the job, and a plan checker will flag a load calc that uses the wrong one.

What a Load Calc Needs to Show the AHJ

A load calc that clears plan check the first time includes:

• Existing connected load, itemized, not just a panel total

• New load being added, itemized (EV charger, generator, HVAC, panel-fed subpanel, etc.)

• Method used, standard or optional, with the Article 220 section cited

• Demand factors applied, shown step by step, not just a final number

• Calculated demand load, compared against the proposed service or panel rating

• Margin, if the AHJ or utility requires headroom above calculated demand

  
  

If any of these is missing, expect a correction letter.

Where This Shows Up Most: Panel Upgrades

Load calc rejections are especially common on panel upgrade permits, because the whole point of the upgrade is usually to add capacity for something else — an EV charger, a generator, electrification of gas appliances. The AHJ wants proof the new service size is actually justified by the calculated demand, not just "bigger is safer."

I handle this as part of every panel upgrade package: panel upgrade permit drawings include a full Article 220 load calc, sized correctly for the method that applies to your job, tied to a one-line diagram and panel schedule the AHJ can actually check against.

Already Got a Correction Letter?

If your load calc already got red-lined and you need it fixed fast, send me the AHJ's comments and the existing drawings — I'll tell you exactly what's wrong and get corrected, re-stamped drawings back to you. That's plan check PE review.

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Get a quote in 1 business day. You'll work directly with the PE — no project managers, no back and forth. Get your load calc and panel upgrade drawings