House Electrical Load Schedule: Demand, Breakers & Cables

Connected load and generic demand

For each circuit, $S_i=P_i/\mathrm{pf}_i$ and $I_i=S_i/U_i$, with kVA converted to VA. The generic IEC-style preset is an editable engineering scenario, not an IEC residential demand-factor table. Apply each demand factor $k_i$, then the separately justified board simultaneity $k_s$: $S_d=k_s\sum k_iS_i$. If C9/C10 are interlocked, use their larger contribution to the total. In strict terminology the board diversity factor is $D=1/k_s\ge1$; the entered $k_s\le1$ is coincidence/simultaneity. Schneider's demand guide explains this distinction and why local factors differ.

Largest-first allocation places each single-phase circuit on the least-loaded phase. Both HVAC alternatives participate in this physical allocation. With an HVAC interlock, calculate cooling and heating scenarios separately and size the generic main for the largest phase current in either scenario, then apply board simultaneity and growth. The chart shows individual demands before the board factor. In NEC mode it shows connected loads, with 240 V circuits shared across both legs; it does not allocate NEC service demand or calculate a code neutral load. Allocation is a deterministic heuristic, not a guaranteed optimum.

NEC optional-method structure

The NEC 2023, 220.82 worksheet uses eligible floor area at 3 VA/ft² and 1.5 kVA per small-appliance/laundry circuit. These allowances replace actual C1–C4 loads for service calculation; their physical branch currents still use the entered loads. C5–C8 and C11 enter the general nameplate subtotal. Apply the first 10 kVA at 100% and the remainder at 40%, then add the governing HVAC term. The comparison table always displays this separate worksheet; select NEC mode to edit its allowances. The basis is documented by the Truckee and Garden Grove municipal worksheets.

C9 is cooling or heat-pump compressor input, and C10 is resistance or supplemental heat. Compare cooling with 65% resistance heat for fewer than four controlled units, 40% for at least four, or full storage heat. A heat pump with auxiliary heat uses compressor plus 65% auxiliary heat; with compressor lockout, compare compressor with the factored auxiliary load. Corresponding factors are editable. C11 enters at nameplate by default. NEC 2023 220.82(A) permits this calculation instead of Part III; its 220.57 minimum is therefore not silently imported. An optional project EVSE floor is editable, with zero meaning nameplate. Obtain the AHJ’s interpretation and check the adopted edition, especially for EVSE or energy management. The NFPA public record gives the existing 220.82 text as well as Part III 220.57; proposals within that record are not adopted rules. No automatic EMS credit is taken.

Protection, cables and supply capacity

Branch design current uses full connected current and the explicit design multiplier; service demand factors never reduce it. The default 1.25 treats all branch load as continuous. NEC C2–C4 are fixed 20 A kitchen/laundry receptacle circuits under 210.11(C)(1)–(2); a design current above 20 A is rejected, with instructions to split the load across additional physical circuits and update allowance counts. These breakers are not upsized to solve an overload. Weld County's 2023 NEC guide confirms these circuit ratings (pp.3–4).

For C11 identified as EVSE in NEC mode, the branch multiplier is at least 1.25 regardless of the discretionary input. This enforces ordinary NEC 2023 625.41 continuous-duty protection independently of the 220.82 service worksheet: 48 A charging requires at least 60 A protection, matching Tesla's published table. Reductions for special continuous-duty assemblies or managed charging are not modeled. Other rows select the next rating in the product-based assortment, with a 15 A floor for NEC C1. Equipment-specific maximum protection and MCA/MOCP remain separate. The main uses the selected demand method, growth and minimum service rating.

The generic thermal screen requires corrected manufacturer ampacity $I_z\ge I_n$ and the entered minimum area. Manufacturer Eland NYY-J product ratings at 30 °C in air are attached as s2, pp.5–6. Branches use the 3-core subset; the three-phase main uses the 5-core subset, available here only through 25 mm². No standard ampacity table is reproduced. The correction factor must describe the actual installation. The schedule's Base amp. column is the required uncorrected ampacity. NEC mode displays required base ampacity equal to the breaker current and asks for an eligible listed cable; it does not recommend NYY-J or apply the generic correction.

Generic supply phase-capacity equivalent is $nU_{LN}I_{main,design}$; NEC uses its calculated VA including growth. Divide by target utilization and round upward in the selected kVA increment. This is a planning capacity, not a verified transformer product or its protection design.

Check each cable in the published Cable Size calculator

Carry the circuit current, candidate breaker, conductor size, actual voltage and one-way route length to its cable check. For the main, carry the design current and selected main rating. Confirm operating temperature, installation thermal paths, voltage drop, fault-loop/disconnection and manufacturer protection data. The links target the currently published catalog entry.

• C1: Lighting / general outlets — Cable Size (https://staging.wiredwhite.com/calcs/cable-size-and-voltage-drop-calculator/)
• C2: Kitchen small appliance 1 — Cable Size (https://staging.wiredwhite.com/calcs/cable-size-and-voltage-drop-calculator/)
• C3: Kitchen small appliance 2 — Cable Size (https://staging.wiredwhite.com/calcs/cable-size-and-voltage-drop-calculator/)
• C4: Laundry receptacle — Cable Size (https://staging.wiredwhite.com/calcs/cable-size-and-voltage-drop-calculator/)
• C5: Cooker / range — Cable Size (https://staging.wiredwhite.com/calcs/cable-size-and-voltage-drop-calculator/)
• C6: Water heater — Cable Size (https://staging.wiredwhite.com/calcs/cable-size-and-voltage-drop-calculator/)
• C7: Dryer / fixed appliance — Cable Size (https://staging.wiredwhite.com/calcs/cable-size-and-voltage-drop-calculator/)
• C8: Dishwasher / fixed appliance — Cable Size (https://staging.wiredwhite.com/calcs/cable-size-and-voltage-drop-calculator/)
• C9: Cooling / heat-pump compressor — Cable Size (https://staging.wiredwhite.com/calcs/cable-size-and-voltage-drop-calculator/)
• C10: Heating / auxiliary heat — Cable Size (https://staging.wiredwhite.com/calcs/cable-size-and-voltage-drop-calculator/)
• C11: EVSE / other fixed load — Cable Size (https://staging.wiredwhite.com/calcs/cable-size-and-voltage-drop-calculator/)
• Main feeder — Cable Size (https://staging.wiredwhite.com/calcs/cable-size-and-voltage-drop-calculator/)

• Default house: eleven available physical circuit slots, nine enabled; generic three-phase 230 V phase to neutral, unity power factors except C9 at 0.9. Powers and demand factors are explicit hypothetical design inputs, not measured usage or country-prescribed values.
• All generic rows are phase-to-neutral single-phase circuits. Balanced three-phase appliances and line-to-line generic loads need a separate model. Changing method does not claim that the physical installation has been rewired.
• NEC mode is fixed to 120/240 V split phase: C1–C4 and C8 are 120 V; C5–C7 and C9–C11 are 240 V. This fixed connection template must match actual equipment. Optional-method eligibility assumes one dwelling, a single qualifying service/feeder, and at least 100 A.
• C1 is one lighting/general-use circuit slot, not an entire real house lighting/receptacle layout. The service floor-area allowance covers general use independently. More circuits than these eleven slots require a larger installation schedule; a zero slot is omitted rather than treated as a minimum mandatory circuit.
• Sinusoidal RMS steady-state loads with nonleading power factor. Arithmetic sums of apparent powers are conservative where power factors differ. No motor starting or harmonic neutral heating is modeled.
• Generic cable correction 0.8, minimum branch area 2.5 mm² and main area 4 mm² are explicit project assumptions. Obtain local minimum areas and applicable rating/correction procedures. Manufacturer nominal metric sizes retain their product names when display units change.
• Growth multiplier 1, utilization 0.8 and 5 kVA rounding are editable planning choices. A main smaller than a branch breaker does not establish selectivity or a guarantee that simultaneous nameplate loads can run.
• Both drawings are conceptual single lines: every enabled circuit remains individually protected. Phase groups in the first drawing are not additional calculated feeder breakers. Earthing, neutral conductors, RCDs and auxiliary devices are omitted for clarity.
• In NEC mode the fixed 20 A C2–C4 rows cannot represent larger dedicated appliance circuits. Add physical circuits and revise the kitchen/laundry service allowance counts when splitting a load. C11 EVSE branch protection always uses at least 125% of connected current, including when a lower discretionary multiplier is entered.

Rules/source review date: 2026-10-26. Generic coordination follows the overload-screen principle associated with IEC 60364-4-43:2023, edition 4.0; the full device criterion, breaking capacity and installation requirements are not established by this screen. The optional-method basis is NFPA 70 (NEC), 2023 edition, 220.82, using nameplate EVSE load unless the user specifies a project minimum. NEC 2026 is now published; this tool deliberately identifies its 2023 basis and does not claim the editions are interchangeable. Check against the standard in force and the authority having jurisdiction.

A licensed electrician or other locally qualified electrical designer must design the installation; installation work belongs to qualified persons. This calculator supports learning and preliminary schedules, not permit approval.

Apart from the fixed NEC kitchen/laundry breaker ratings and ordinary EVSE branch minimum enforced here, no checks are made for neutral sizing, triplen harmonics, earthing/bonding, RCD/AFCI/GFCI requirements, selectivity, fault breaking capacity, disconnection time, short-circuit withstand, voltage drop, equipment minimum/maximum circuit protection or conductor terminal limits. In NEC mode confirm listed cable ampacity, small-conductor restrictions, termination ratings, minimum circuits and appliance/motor-specific articles. Special equipment can invalidate an ordinary next-breaker selection. The tool does not support reducing EVSE branch protection below the ordinary 125% minimum through a 100%-rated assembly or energy-management exception.

A positive cable candidate means only that the modeled ampacity and area screen passes. It is not authorization to install that cable. A zero candidate means off or outside the source subset, distinguished in the status text. Five-core source data above 25 mm² are not extrapolated.

The Truckee reference retains its published 7.0 kVA EVSE nameplate and reproduces 29.52 kVA. A separate sensitivity case adds an explicit 7.2 kVA project floor and obtains 29.60 kVA; that case is not a correction of the published optional calculation or a claim that Part III 220.57 governs it. The apartment-block reference verifies only the demand arithmetic, not house branch circuit design.