Add specific equipment, appliance, motor, sign, show-window, or EVSE loads. Each row is treated as its own branch-circuit requirement and is never distributed across the general lighting or receptacle circuits.
| Description | VA or W | Unit | Qty | Voltage | Category | Cont. | Rating | Circuits |
|---|
Add circuits to build a fixed arrangement for the general-purpose branch-circuit sizing load (lighting + receptacles). Because you commit to a specific number of circuits here, PASS / CAUTION / FAIL is meaningful. Dedicated loads are sized separately on the Dedicated Loads tab.
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| Step | Description | Calculation | Result |
|---|---|---|---|
| Enter inputs to generate trace. | |||
Confirm each against NFPA Link / licensed NEC text / your AHJ before any design use.
Paraphrased logic generated from the selected edition — consult the NEC for binding language.
Why This Matters
Branch-circuit loading determines how many circuits a space needs and how large they must be. Every panel schedule, wire pull, and breaker selection depends on these numbers.
- Under-sized circuits trip repeatedly — nuisance outages.
- Over-sized circuits waste panel space and cost.
- The NEC unit-load method provides a standardized baseline without knowing every fixture in advance.
Common Mistakes (that this tool now guards against)
- 180 VA per receptacle instead of per yoke: A duplex on one yoke is one 180 VA unit, not two.
- Adding dwelling receptacles separately: Dwelling and hotel/motel guest-room general-use receptacles are already in the unit lighting load (220.14(J)).
- Applying 125% to everything: The continuous multiplier applies only to loads that are actually continuous, and only for conductor/OCPD sizing.
- Double-counting 125% under NEC 2020/2023: Those tables carry a note saying the 210.20(A) continuous multiplier is already included in the unit loads. Re-applying it inflates the load. This tool suppresses it for table-based non-dwelling lighting and says so in the trace.
- Using 2017 unit loads under a 2020+ citation: The 2020 cycle reconstructed the table for LED lighting — offices went 3.5 → 1.3 VA/ft², but armories/auditoriums went up 1.0 → 1.7. Using the old number is not always conservative.
- Entering a custom VA/ft² below the table value: The unit load is a minimum — “shall not be less than.” A measured lighting design lower than the table does not lower the calculated load.
- Treating 220.14(K) as optional: For banks and offices it is a “shall” provision. The receptacle load is the greater of 180 VA/yoke or 1 VA/ft².
- Applying the receptacle demand factor to the 1 VA/ft² value: The 220.44/220.47 demand covers loads calculated per 220.14(H) and (I) only — not the 220.14(K)(2) area-based value.
- General-use receptacles on 277 V: Not permitted (210.6). This tool blocks it.
- General-use receptacles on a 30 A circuit: Not permitted unless a listed 30 A equipment receptacle is used.
- Forgetting the dwelling required circuits: 210.11(C) mandates two small-appliance circuits, a laundry circuit, and a bathroom circuit regardless of the general-lighting math.
- Spreading dedicated loads across general circuits: Dedicated loads get their own circuits.
What Changes With the Edition
Connected vs. Calculated vs. Sizing
Connected = raw unit loads. Calculated = NEC unit-method load. Sizing = calculated plus the 125% adder on continuous loads for conductors/OCPD.
Receptacle Load
180 VA per yoke/strap (220.14(I)). Not about what is plugged in — about what could be. For offices/banks, compare against 1 VA/ft².
Branch-Circuit Loading
Total VA on a circuit vs. rated capacity. Voltage × ampere rating = circuit VA. Exceed it → more circuits needed.
Continuous vs Non-Continuous
Continuous = max current for 3+ hours. Conductor/OCPD sizing uses 125% of the continuous portion. Note: a load-calculation article does not necessarily itself apply 125%.
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Runs deterministic unit tests against the calculation engine (the same pure functions used by the UI and by the Node test file). Results also print to the browser console. Append ?selftest=1 to auto-run on load.