What Is a Load Calculation-and Why It Matters Before Renovations

Thinking about a kitchen refresh, adding a rental suite, or installing a heat pump or EV charger? Before you pick fixtures or book drywall, you need to know whether your electrical system has the capacity to handle what's coming. That's exactly what a load calculation tells you.

Bottom line: A load calculation is a math-based assessment of how much electrical demand your home has now-and how much it will have after your renovation-so you can decide if your existing service (for example, 100A or 200A) is enough, or if you need upgrades or smart alternatives.

What is a load calculation?

A load calculation adds up your home's expected electrical demand, applies diversity (not everything runs at once), and compares that total to your main service size. It's required for many permits and is the only reliable way to know whether you can add new circuits, a heat pump, or EV charging without tripping breakers or overloading your service.

Why it matters before you renovate

- Safety and code compliance - Prevent overheated conductors, nuisance trips, and failed inspections.

- Budget accuracy - Avoid surprise costs mid-project if you discover a panel or service upgrade is needed.

- Scope clarity - Decide early between 100A vs 200A, subpanels, or load-management devices.

- Future-proofing - Plan for tomorrow's loads (second EV, hot tub, suite) while the walls are open.

- Permit approvals - Many projects require a load calculation to issue or close the permit.

What we include in a professional load calculation

- Home size (square footage) and mandatory base loads

- Heating type (electric heat vs heat pump) and any auxiliary heat

- Major appliances (range, dryer, hot water, laundry)

- Renovation loads (new circuits, lighting, kitchen receptacles)

- EV charging (actual charging rate, 32A vs 40A, etc.)

- Special loads (hot tub/sauna, well pump, shop tools)

- Diversity factors (what realistically runs together)

- Service and panel review (space, breaker types, condition, grounding/bonding)

You get a clear answer: stay at 100A, move to 200A, or use an alternative (like a subpanel or an approved load-management solution).

Common renovation scenarios (and how load calculations guide decisions)

- Kitchen remodel New circuits for dedicated appliances and more counter receptacles can push a full panel past its limit. The calculation shows whether a panel refresh or a service upgrade is needed.

- Adding a heat pump Great for bills and comfort, but it's still a large load. If you don't have electric heat and the numbers work, 100A can sometimes support a heat pump; otherwise, 200A may be the cleaner path.

- EV charging A 32A Level-2 charger might fit on 100A if you don't have electric heat and the calculation shows headroom. If you want 40A charging-or heat pump and EV-200A often makes life easier.

- Secondary suite or shop Extra kitchen/laundry or big tools add significant demand. The calculation will reveal whether you need 200A or a different design.

100A vs 200A - how the load calculation informs the choice

- 100A works when overall demand is modest, especially if you don't have electric heat and you're adding one big load (for example, a heat pump or a 32A EV charger).

- 200A shines when you want multiple modern loads (heat pump and EV, hot tub, shop tools) or room to grow without juggling what can be on at the same time.

Smart alternatives the load calculation can unlock

- Subpanel - Organizes circuits in an addition or garage; doesn't raise total capacity, but improves layout.

- Load-management device - In some designs, lets a large load (like EV charging) pause when demand is high, avoiding a full upgrade.

- Panel refresh at same amperage - New breakers, AFCI/GFCI where required, labeling, and whole-home surge protection can solve safety and reliability issues even if you keep your current service size.

When to do it-and what to prep

When: As soon as you have a rough scope and appliance list-before pulling permits or finalizing quotes.

What to bring: Square footage, heating type, a list of existing and planned appliances with nameplate ratings (or model numbers), and any future wish-list items (hot tub, second EV, shop tools).

FAQ

Will a load calculation tell me if I must upgrade to 200A?

Yes. It compares your projected demand to your current service so you can choose between staying at 100A, upgrading to 200A, or using alternatives.

If I'm careful, can I skip the calculation?

No. Guessing leads to tripping breakers, failed inspections, or mid-project change orders. The calculation is quick and saves money.

Will more capacity lower my bill?

Capacity doesn't equal consumption. Bills go down with efficient equipment (heat pumps, LEDs) and how you use power.

Ready to renovate with confidence?

New Leaf Electric - Local, Reliable, Professional

Proudly serving Comox, Courtenay, Campbell River, and surrounding communities.

We'll run a clear, professional load calculation, explain your options in plain language, and price the right solution-whether that's staying at 100A, moving to 200A, or using a smart alternative. Contact New Leaf Electric for more information-we'd be happy to help.