Add EV charging
Use the charger's maximum or configured output, vehicle and daily charging need, existing household loads and any approved EV energy-management strategy.
Canada homeowner planning guide
Electrical Load Calculation in Canada: Capacity Evidence Guide
Do not choose 100A, 200A or load management from breaker totals. Start with a defined decision, verified equipment, the locally accepted method, realistic future scenarios and a record another qualified reviewer can audit.
13jurisdictions
7project gates
36official sources
Safety boundary
Do not total breaker handles, infer capacity from monthly bills or use a web calculator to resize service, feeder or overcurrent protection. Do not open a panel to gather inputs. Verified ratings, equipment data, demand treatment, controls and locally adopted requirements belong in qualified design.
Capacity evidence planner
Find the missing input before choosing amps
This tool does not calculate service or feeder size. It identifies the project boundary, source records and locally accepted evidence needed for a reviewable capacity decision.
Planning inputs
Current evidence gate
Compare suitable designs against one documented load case
Source records the file needs
- Verified service equipment, conductor and main-protection ratings
- Present, committed and staged future equipment scenarios
- Utility feasibility, approved load-management alternatives and owner priorities
Committed additions boundary
Include equipment already selected or contractually planned, with exact settings and sequencing. Keep undefined wish-list loads out of the accepted base case.
Breaker totalsUnsupported future allowanceUtility capacity assumed
Method next action
Have the responsible qualified person apply the method currently accepted for the address, with source nameplates, units, demand factors, assumptions and the calculation boundary recorded.
Breaker totals, monthly bills and this planner are not electrical load calculations.
Short answer
What this project must establish
Canadian electrical requirements are adopted and administered locally. This guide explains the durable planning questions; your province or territory, local authority, serving utility, equipment instructions, and responsible contractor determine the property-specific answer.
Find your jurisdiction guideConnected load, calculated demand, measured peak demand and electrical energy are related but different quantities.
Branch-breaker ratings protect circuits and cannot simply be added to determine a dwelling's service demand.
The calculation boundary can be the dwelling service, a feeder, a suite, a subpanel or one proposed load and must be named.
The authority for the address decides which prescriptive, historical-demand, optional or other path is accepted and which qualifications, forms and markings apply.
BC Hydro describes traditional and 12-month meter-data approaches for eligible homes, while Technical Safety BC publishes project-specific limits and treatment; that BC guidance is not a Canada-wide permission.
Historical data can miss future equipment, unusual weather, vacancy, changed occupancy or loads added during the evidence period and must be interpreted within the accepted method.
Approved load management can change coincident demand only when the calculation identifies what is monitored, controlled, limited and expected to happen on loss of control or communication.
A result near a service, feeder or control threshold deserves input and assumption review plus suitable alternatives, not false precision or automatic upsizing.
Project triggers
Situations that change the scope
Install a heat pump
Include outdoor and indoor units, auxiliary or backup heat stages, retained heating, cold-weather controls, water heating and exact electrical data.
Create a secondary suite
Additional cooking, heating, hot water, laundry, cooling, occupancy and possible EV charging can affect dwelling service and feeder design as well as panel spaces.
Replace or enlarge service
Use current, committed and defined future scenarios to compare 100A, 200A or another service design and avoid both unsupported upsizing and hidden constraints.
Add a feeder or subpanel
State whether the calculation addresses the upstream dwelling service, the new feeder, the subpanel or all three. Added breaker spaces do not create service capacity.
Use load management
Identify the monitored point, controlled loads, maximum settings, operating priority, communications and safe failure behaviour that the calculation relies on.
Decision guide
Resolve the design choices before pricing
A defensible quote connects the existing condition and calculated demand to the proposed correction. It also separates contractor work, authority approval, and utility-owned scope.
01
What exact decision and boundary apply?
Name the property, service, feeder, panel or dwelling unit being evaluated and the exact proposed equipment. A service calculation does not automatically prove feeder capacity, and a subpanel adds spaces rather than upstream capacity.
02
Which method is accepted here?
Confirm the province or territory, delegated authority, permit path and serving utility. Record whether the project uses the current prescriptive method, an accepted historical-demand route or another documented path and which forms or labels apply.
03
Where did every input come from?
Use verified service and feeder ratings, equipment nameplates, schedules, floor area where required, heating and hot-water configuration, suite details, EV settings and control documentation. Mark provisional selections as provisional.
04
Is historical data suitable?
Record interval resolution, duration, seasons, occupancy, vacancy, weather, loads added or removed and the authority's required treatment. Energy values do not become peak-demand evidence merely because they are exported from a utility portal.
05
Which present and future cases matter?
Separate as-is, committed and staged future scenarios. Include selected equipment and settings without silently adding undefined future allowances or assuming a utility will provide larger capacity later.
06
How is managed load enforced?
State the monitored point, controlled equipment, maximum settings, priority logic, override behaviour, communications, approved product and safe failure state. A promise of smart management is not a design input.
Option matrix
Five capacity paths that answer different questions
Use the path accepted for the address and project. The purpose is not to manufacture spare amps; it is to document a suitable circuit, feeder, control or service design from evidence that can be reviewed and updated.
| Evidence path | Best use | Required record | Important limit |
|---|---|---|---|
| Prescriptive calculation | New construction, changed occupancy, incomplete operating history or projects where the locally adopted calculation method is required. | Boundary, verified equipment and dwelling inputs, units, demand factors, calculations, assumptions and responsible provider. | Proxy and demand factors must be applied under the current local method; a generic online worksheet is not authority acceptance. |
| Accepted historical-demand method | Eligible existing installations with the required utility data period and no disqualifying occupancy or load changes under the local rule. | Utility source, interval and period, peak treatment, safety factor or other required conversion, context, new loads, date and required marking. | Availability and treatment vary. Monthly bills, short samples and one jurisdiction's method cannot be generalized across Canada. |
| Equipment configuration or reduction | Meeting the owner need with a lower EV setting, sequenced backup heat, efficient replacement or removal of loads no longer used. | Exact equipment, settings, operating sequence, removed loads and updated calculation for the selected design. | A planned reduction counts only when the final installed configuration and owner operation support it. |
| Approved load management | Keeping flexible loads within a defined service or feeder limit by monitoring and controlling coincident operation. | Approved equipment, monitored point, controlled loads, maximum settings, priorities, communications, failure state, testing and labels. | It does not repair deficient equipment or create utility capacity, and not every control strategy is accepted for every load or jurisdiction. |
| Service-capacity increase | Projects whose accepted demand evidence and owner objectives cannot be met by a suitable retained-service design. | Load case, utility application and design, service and meter scope, permit, outage, inspection, reconnect, restoration and closeout file. | A larger panel alone is not a service upgrade; utility feasibility, route, equipment and customer-owned work still govern scope and timing. |
Across Canada
Start with the authority and utility for the address
Canada does not have one electrical approval path, permit office, utility boundary, inspection sequence, or fee. Use the provincial or territorial guide as the first routing layer, then confirm the municipality, project scope and serving utility.
AB · province
ABAlberta
Permits are administered through accredited municipalities or safety codes agencies. Calgary and Edmonton have their own processes; many other communities use an accredited agency.
Service changes may require coordination with ENMAX, EPCOR, FortisAlberta, ATCO, or another local wire service provider. Confirm ownership and lead times before scheduling an outage.
BC · province
BCBritish Columbia
Technical Safety BC requires permits for regulated electrical installations and alterations in its jurisdiction. Burnaby, Maple Ridge, North Vancouver, Surrey, Victoria, Vancouver, and West Vancouver are among the jurisdictions that issue their own permits.
A service-capacity change can involve BC Hydro or a municipal utility, meter-base requirements, service design, and scheduled disconnection. Utility approval is separate from the electrical permit.
SK · province
SKSaskatchewan
Electrical permits cover new wiring and alterations to electrical installations. The permit holder is responsible for the declared work and required inspection process.
Capacity increases, meter relocations, overhead-to-underground changes, and service redesigns should be submitted to SaskPower or the serving utility early in planning.
MB · province
MBManitoba
The permit authority depends on location. Service equipment work is outside the scope of ordinary homeowner self-wiring and should be completed by a licensed electrician.
Panel projects that alter the consumer service, meter, or connection require Manitoba Hydro or Winnipeg coordination in addition to the electrical permit.
ON · province
ONOntario
An ESA notification should be filed before work starts. A municipal building permit is not the same as an ESA electrical notification, and some projects may require both.
A service-size change may also require approval and scheduling from the local distribution company. Requirements vary among Hydro One and municipal utilities.
QC · province
QCQuebec
The contractor should confirm the declarations, municipal requirements, and distributor process that apply to the property and scope. Requirements differ from the ESA-style system used in Ontario.
Service capacity, meter, mast, and connection changes should be coordinated with Hydro-Quebec or the serving municipal distributor before an outage is scheduled.
NB · province
NBNew Brunswick
Wiring permits are required before work starts for regulated installations. Inspection and plan-review requirements depend on project scope and risk.
NB Power or a local municipal utility may need to review service capacity, metering, connection, or outage arrangements.
NS · province
NSNova Scotia
A wiring permit covers new electrical work and modifications to existing installations. Permit issuance and inspection are handled by the applicable utility inspection department.
The serving utility should be involved when a panel project changes the service, meter, connection, or energization schedule.
PE · province
PEPrince Edward Island
A separate permit is required for each work site. The licensed electrical contractor applies and provides the required project and service information.
Service and meter changes should be coordinated with Maritime Electric or the serving municipal utility before installation dates are finalized.
NL · province
NLNewfoundland and Labrador
The Government Service Centre administers permits and inspections. Panel, switchboard, generator, and large battery work falls within the regulated process.
Newfoundland Power, Newfoundland and Labrador Hydro, or a local system may need to coordinate service changes, metering, and reconnection.
YT · territory
YTYukon
Building Safety administers electrical permits. Inspection stages include rough-in, service wiring, and final finish, with advance notice required.
Service design and connection may involve ATCO Electric Yukon, Yukon Energy, or a local provider. Remote access and seasonal work windows can affect scheduling.
NT · territory
NTNorthwest Territories
Permits cover new installations, rewiring, and additions. Authorization is also required before power connection or concealment of rough wiring.
Service coordination may involve Northland Utilities, the Northwest Territories Power Corporation, or a local operator. Remote-community logistics can materially affect timing.
NU · territory
NUNunavut
Permit applications identify the contractor, registered electrical worker, work location, occupancy, service ampacity, voltage, and project value. Confirm the current form and fee with the territorial office.
Qulliq Energy Corporation and the territorial authority may both be involved where service capacity, metering, generation, or energization changes.
What changes the project cost
A Canada-wide installed price is not a substitute for a site-specific scope. Compare the same equipment, responsibilities, exclusions, and closeout standard.
Data quality
Availability and accuracy of equipment schedules, service and feeder records, interval data, renovation plans and future-load specifications affect investigation time.
Method and authority
Required forms, measured-data treatment, design responsibility, jurisdiction review, utility involvement and engineering where required affect scope.
Property complexity
Suites, multiple panels, outbuildings, mixed heating, solar, batteries, generators, multiple EVs and unusual occupancy create more boundaries and scenarios.
Meter-data analysis
Data access, interval resolution, duration, cleaning, weather and occupancy context and reconciliation with future equipment can require separate analytical work.
Scenario and control design
Current and future cases, equipment alternatives, managed-load settings, seasonal operation, communications and failure-state review add value and effort.
Resulting physical project
Circuit, feeder, panel, management or service changes, permits, utility work, outage and restoration are costs supported by the result, not part of the calculation fee alone.
A jurisdiction-ready project sequence
Do not schedule around an assumed installation day until equipment, permits, utility work, inspection, outage, and restoration dependencies are known.
- STEP 1
Define the decision
Name the proposed load, service, feeder or panel and the exact question the calculation must answer before selecting a method.
- STEP 2
Confirm the accepted path
Identify the authority and utility for the address, eligible designer or permit holder, current forms and whether a prescriptive or measured-data option is accepted.
- STEP 3
Collect source evidence
Gather verified service and feeder ratings, nameplates, heating and hot-water systems, appliances, EV settings, suite information, plans, meter data and future-load list.
- STEP 4
Normalize operating assumptions
Record equipment configuration, backup heat, controlled-load limits, occupancy and future scenarios so competing proposals solve the same operating need.
- STEP 5
Apply and document the method
Show units, source inputs, demand factors, data period, calculations, assumptions and management controls clearly enough for qualified review.
- STEP 6
Test suitable alternatives
Compare equipment settings, staging, approved management, efficient equipment, feeder or panel changes and service sizes against the same requirements.
- STEP 7
Attach the final record
Update the calculation for the selected equipment and settings, then retain it with authority or utility decisions, permit and inspection outcome and as-built information.
Questions every written quote should answer
- What exact decision and electrical boundary does this calculation address?
- Which method and form are accepted by the local authority?
- Who is responsible for the calculation and permit design?
- Where did each service, feeder and equipment input come from?
- Which exact EV, heat-pump, suite and future-load settings are included?
- How are meter interval, duration, weather, vacancy and occupancy handled?
- Which demand factors and assumptions materially affect the result?
- What loads, settings and failure state does management rely on?
- Which suitable alternatives and future scenarios were tested?
- Will I receive the calculation, input schedule, data period, control settings and final accepted record?
Build an auditable project file
Another qualified professional should be able to understand what existed, why the scope changed, who approved it, what was installed, and how the project closed.
Existing condition
Service rating, closed-cover equipment identification, observed condition, symptoms, accessible configuration, and the planned loads or project trigger.
Approved scope
Legal contractor, equipment, circuit and service work, permit holder, inspection, utility responsibilities, restoration, exclusions, and change-order rules.
Installation record
Permit number where required, approved equipment, labelled circuits, documented changes, inspection milestones, and utility instructions where applicable.
Closeout file
Final acceptance or inspection status, equipment information, settings, warranty, utility records, paid invoice, and the responsible contractor's contact details.
Continue researching
Related Canadian guides
100A versus 200A service
Apply the calculation to service-size decisions.
Open guide100A to 200A service upgrade
Plan utility and service work after capacity need is established.
Open guideLoad management guide
Understand monitored demand, settings and control alternatives.
Open guideElectrical panel upgrades
Separate condition, spaces, controls and service capacity.
Open guideEV charger installation
Use exact charger output and management options in the design.
Open guideHeat pump panel planning
Include backup heat and control sequence in the input schedule.
Open guideSecondary suite panel planning
Coordinate dwelling, suite, feeder and metering decisions.
Open guideSubpanel installation article
Separate feeder capacity from physical circuit spaces.
Open guideMeter base and service entrance
Verify the service equipment behind the rating input.
Open guide200A versus 400A guide
Apply the same evidence framework to larger service choices.
Open guidePrimary references
Check current requirements
Forms, code editions, inspection procedures, utility standards, equipment, and incentive programs can change. Verify the current local rule before relying on a project detail.
BC HydroUnderstand your home's electrical capacityBC HydroUnderstanding overloaded electrical servicesTechnical Safety BCDemand factors and historical data for a detached single dwellingTechnical Safety BCEVSE and electric vehicle energy management systemsElectrical Safety AuthorityMaximum circuit loading and demand-factor examplesElectrical Safety AuthorityElectric vehicle charging systems bulletinManitoba HydroResidential electrical service request checklistManitoba HydroResidential wiring and service-upgrade guidanceBC HydroSecondary customer service requirementsBC HydroElectrical connection requestsEPCORElectrical service connection questionsEPCORNew and upgraded electrical service connection processHydro OneElectrical service upgrade planningHydro One2026 conditions-of-service update summaryHydro-QuebecResidential electrical work requests and project stepsSaskPowerElectrical service requests and readiness guidanceSaskPowerElectric service requirementsNB PowerBuilding, renovation and service-connection stepsNatural Resources CanadaHeating and cooling with a heat pumpNatural Resources CanadaAir-source heat pump sizing and selection guideNatural Resources CanadaElectric vehicle charging levels and fundamentalsTechnical Safety BCBritish Columbia: Electrical installation permitsElectrical Safety AuthorityOntario: Notifications and inspectionsGovernment of AlbertaAlberta: Permits and Alberta's safety code systemTechnical Safety BCBritish Columbia: Electrical licencesSaskPowerSaskatchewan: Request electrical service changesManitoba HydroManitoba: Electrical permits and inspectionsElectrical Safety AuthorityOntario: Find a Licensed Electrical ContractorRegie du batiment du QuebecQuebec: Electrical contractor licensingGovernment of New BrunswickNew Brunswick: Technical inspectionsGovernment of Nova ScotiaNova Scotia: Electrical safetyGovernment of Prince Edward IslandPrince Edward Island: Electrical work in PEIGovernment of Newfoundland and LabradorNewfoundland and Labrador: Electrical permits and inspectionsGovernment of YukonYukon: Electrical permits and inspectionsGovernment of Northwest TerritoriesNorthwest Territories: Electrical permitsGovernment of NunavutNunavut: Annual electrical permit application
Canadian questions
Residential capacity and demand evidence FAQ
What is a residential electrical load calculation?+
It applies an accepted method to verified dwelling and equipment inputs to estimate or establish demand for a service, feeder or proposed load decision.
Can I calculate load by adding all breaker ratings?+
No. Breaker totals do not represent coincident dwelling demand and can greatly exceed service rating. Use the locally accepted method and verified equipment inputs.
Can electricity bills prove spare electrical service capacity?+
Not by themselves. Bills commonly report energy used over a billing period, while capacity decisions concern demand under an accepted method. Suitable interval data may support an accepted measured approach when its period and context meet local requirements.
What is the difference between kilowatts and kilowatt-hours?+
Kilowatts describe a rate of power at a point in time; kilowatt-hours describe energy used over time. A monthly energy total does not reveal every short-duration or seasonal demand peak.
Does a load calculation include future equipment?+
It should include committed additions and clearly defined future scenarios relevant to the decision, with equipment ratings, configured settings, operating assumptions and planning horizon documented.
Who can complete a Canadian electrical load calculation?+
Required qualifications and responsibility vary by jurisdiction and project. Confirm the local authority, utility and permit-holder requirements.
Can load management change the calculation result?+
An accepted control design can limit coincident demand for defined loads. The calculation must identify approved equipment, monitored point, controlled loads, maximum settings, priority logic and failure behaviour.
Does a subpanel add electrical capacity?+
No. A subpanel can add distribution spaces but receives power from an upstream feeder and service. The calculation should state whether it evaluates the new feeder, the dwelling service or both.
Does solar generation reduce the required service size?+
Do not assume so. Customer generation, batteries, export limits and service demand involve separate operating modes and rules. The accepted design must state how each system affects the calculation and utility connection.
Why do two load calculations differ?+
They may use different boundaries, methods, equipment ratings, meter periods, future loads, demand factors or management assumptions. Compare inputs line by line.
How current should a load calculation be?+
Update it when equipment, configured settings, occupancy assumptions, suite plans, service information, accepted methods or the project decision changes. A prior calculation is evidence only for the scenario it documented.
What should I receive with the calculation?+
Keep the project question and boundary, accepted method, verified inputs, assumptions, units, calculations, data period, scenarios, control settings, responsible provider and authority or utility acceptance where applicable.
Is 12 months of smart-meter data enough for a load calculation?+
Not automatically. The authority must accept the historical-demand path for the property and project. The qualified reviewer must confirm the utility source, interval, complete period, occupancy, weather, load changes, peak treatment and any required safety factor, marking or variance.
How much spare capacity does a 100 amp service have?+
There is no reliable Canada-wide amount based on the 100A label alone. Spare capacity depends on the accepted demand evidence, voltage and service design, continuous and intermittent loading treatment, present equipment, planned loads and approved controls.
Do I need a load calculation for an electrical permit?+
Many major-load, feeder, suite and service projects require load evidence, but submission requirements vary by jurisdiction and scope. Confirm the current permit category, accepted method, responsible provider and required form with the authority for the address.
Property-specific next step
Planning electrical panel work?
Send the property location, panel details, project trigger, planned loads, and timing. Provider availability, licensing, scope, price, permit responsibility, and utility scheduling are confirmed before work is booked.
Scope-first project reviewNo DIY panel instructions