Whole Home Electrification Load Calculator

Purpose and model boundary

Compares connected-load, separated-new-load, and metered maximum-demand routes for a before-and-after home electrification project while preserving an auditable twelve-row appliance and equipment inventory.

Do not treat this result as an electrical design, code-compliance determination, permit approval, utility commitment, equipment approval, safety certification, cost quote, or endorsement by a cited source. Service data, panel ratings, conductor properties, equipment loads, route lengths, manufacturer instructions, utility requirements, locally adopted codes, and approval thresholds remain the user's responsibility.

Inputs and units

• load method: a listed route or text value.
• service system: a listed route or text value.
• approved load management: a listed route or text value.
• seasonal coverage: a listed route or text value.
• service rating a: entered in A.
• floor area ft2: entered in ft^2.
• general load va per ft2: entered in VA/ft^2.
• small appliance circuits: entered in circuits.
• small appliance va per circuit: entered in VA/circuit.
• laundry circuits: entered in circuits.
• laundry va per circuit: entered in VA/circuit.
• first block kva: entered in kVA.
• first block factor: entered in fraction.
• remainder factor: entered in fraction.
• new ev ess factor: entered in fraction.
• new resistance heat factor: entered in fraction.
• new other factor: entered in fraction.
• measured peak kva: entered in kVA.
• measured days: entered in days.
• behind meter production kva: entered in kVA.
• measured load factor: entered in factor.
• reserve percent: entered in fraction of service rating.

The project load grid contains 12 fixed data rows plus one header row with these columns: Load label, Include, Project state, Load class, Nameplate kVA (kVA), Planning coincidence (fraction), Managed cap kVA (kVA). Numeric columns retain the units shown here; text, route, and include columns are intentionally unitless.

Governing relationships

For included project row i, effective nameplate is:

S_eff,i = min(S_nameplate,i, S_managed,i)

when the active management route supplies a positive cap; otherwise it is S_nameplate,i (kVA). Planning-coincident load is:

S_coin,i = S_eff,i c_i

c_i is the entered coincidence fraction. Removed/replaced rows reduce the after-project connected-load basis rather than adding to it.

The two-block demand function is:

D(G;T,f_1,f_2) = min(G,T) f_1 + max(G-T,0) f_2

D is in kVA, G is the applicable connected kVA, T is the block threshold (kVA), and f_1 and f_2 are demand fractions. The connected-load routes apply this function to the workbook's before/after or separated-new-load bases; the metered route applies its entered growth and added-project terms to measured maximum demand.

Demand current and service capacity are:

I_demand = 1000 D / (k_V V_LL)

S_service = k_V V_LL I_service/1000

I_demand is in amperes and S_service is in kVA. k_V is 1 for split-phase or sqrt(3) for three-phase, and V_LL is line-to-line voltage (V). Spare current and spare fraction are:

I_spare = I_service-I_demand

f_spare = I_spare/I_service

The recommendation is the first disclosed service-rating candidate not below demand plus the entered reserve.

Calculation sequence

1. Validate every active selector, scalar bound, type, and every fixed-grid entry.
2. Apply the selected route and ignore values from inactive fields.
3. Normalize unit-dependent inputs into the workbook's calculation basis.
4. Evaluate every included row or candidate and aggregate the active schedule.
5. Calculate primary and supporting outputs, populate the authored chart series, and apply derived numeric checks.
6. Return the workbook status with the computed results; invalid input is never converted into a plausible engineering answer.

Outputs and interpretation

• before connected load kva (kVA): Retained plus removed equipment with noncoincident cooling-versus-heating treatment.
• after connected load kva (kVA): Retained plus new equipment with noncoincident cooling-versus-heating treatment.
• selected demand kva (kVA): Demand from the active connected, separated-new-load, or measured route.
• selected demand a (A): Selected kVA converted with the active service-system voltage factor.
• service capacity kva (kVA): Entered service amperes multiplied by the active service-system voltage factor.
• spare capacity a (A): Entered service rating less selected demand current; negative means overload in this scenario.
• spare capacity percent (fraction of rating): Spare amperes divided by entered service rating.
• recommended service rating a (A): First disclosed candidate rating that covers selected current and entered reserve; zero means beyond the ladder.

The chart is an explanatory view of the workbook's named chart ranges. It does not add a separate calculation or replace the numeric outputs.

Validation and status logic

The workbook evaluates Model_Status in the order shown. The first matching condition wins.

Assumptions and limitations

• All shipped default dwelling, service, demand-factor, managed-cap, and equipment values are synthetic illustrative demonstrations and must be replaced with project evidence.

• General, small-appliance, and laundry loads are editable planning inputs rather than embedded jurisdictional requirements.

• Cooling and heating are treated as noncoincident by taking the larger state-specific total; all other included rows are additive.

• The separated-new-load route prorates any remaining first-block headroom across new load, then applies editable class factors to the balance.

• The metered route adds entered behind-the-meter production at the recorded peak, applies an editable multiplier, and adds only positive net new nameplate load.

• Planning coincidence is a scenario output only and does not determine compliance or service adequacy.

• This is a screening workbook, not an electrical design, service authorization, permit calculation, or substitute for the adopted code and utility rules.

• Editable demand factors, management caps, service ladders, and default project rows are synthetic illustrations and require authority-having-jurisdiction and utility confirmation.

• Metered data must be checked for interval quality, seasonality, outages, electrification changes, and behind-the-meter generation at the coincident peak.

• Have a qualified electrical professional verify service, feeder, panel, conductor, overcurrent, load-management, and equipment ratings before procurement or work.

Restrictions and non-computing states

Each numeric control offers a working range chosen for usable entry, which is not always the limit this calculator enforces; a value outside that limit is rejected with a message rather than quietly accepted. The calculator additionally enforces allowed choices, active-field types, complete fixed-grid rows, and conditional or cross-field rules before computing.

Unsupported route values, incomplete rows, out-of-domain inputs, relational failures, nonfinite derived arithmetic, and workbook error tokens are non-computing states. Hidden inputs remain in the values sent to the calculator but must not affect results while those fields are inactive.

Errors and warnings

A rejected entry means the submitted state failed the published input rules. Workbook NOT VALID identifies an invalid active domain or unsupported derived arithmetic. Workbook CHECK retains a finite result while flagging a planning condition that needs review. OK means only that the delivered workbook logic closed within the entered assumptions; it is not code compliance, professional approval, or a safety guarantee.

This version is checked against 160 saved test cases, covering both calculated results and entries that should be refused, run against this exact workbook.

• NFPA 70 existing-dwelling load-calculation development record - Official standards-development record for existing-dwelling connected-load and separated-new-load method context, cited only on References and Disclaimer. Clause names and public-development context only; no licensed code table or prose is embedded.
• NFPA 70 metered-load development record - Official standards-development record for optional measured maximum-demand method context, cited only on References and Disclaimer. Clause names and public-development context only; no licensed code table or prose is embedded.
• Washington State Register metering provisions - Official state rulemaking source for one-year demand records and local seasonal-period context. Official public state-government rulemaking source; the route is independently implemented and no clause text or table is copied or reproduced.

Licensing conclusion: No licensed, proprietary, manufacturer, utility, product-price, code-table, forecast, or external dataset is embedded. The calculator independently implements general engineering arithmetic from cited public and official sources; all defaults, labels, conductor/load rows, equipment assumptions, diagrams, and test values are synthetic illustrations.