Panel Schedule Calculator

A panel schedule is the working record of every circuit fed from a panelboard — circuit label, pole count, phase assignment, and connected VA. Before that schedule becomes a finished document for inspection or a service upgrade submittal, the raw circuit data has to be totaled by phase and checked against the panel’s ampacity and physical space. The Panel Schedule Calculator performs that row-by-row totaling: it takes each circuit’s Label, Phase placement, Poles, and Load (VA), and returns the Connected load, the per-phase totals (Phase A load, Phase B load, Phase C load), the Average phase load, and an Imbalance estimate. The output is the arithmetic basis for feeder sizing review, panel capacity checks, and identifying which phase is carrying disproportionate load before a service is finalized.

Circuit Row Inputs

Each row in the calculator represents one circuit as it would appear on a physical panel schedule:

• Label – the circuit description (Lighting, Receptacles, HVAC, Office, etc.)
• Phase placement – which bus phase(s) the circuit occupies: A, B, C, or a two-phase combination such as A-B for a 2-pole circuit
• Poles – 1 for a single-pole branch circuit, 2 or 3 for multiwire or multi-phase circuits, which also determines how many panel spaces the breaker occupies
• Load – the connected VA for that circuit

Panel-level fields apply across all rows: Phase voltage (line-to-neutral voltage used for the panel, 120 V in this example), Panel rating (the panel’s ampacity rating, 100 A here), and Panel spaces (total breaker slots available, 42 here).

Connected Load Calculation

Connected load is the straight sum of every row’s VA entry, independent of phase placement:

Connected load = Σ (Load for each row)

For the four rows entered — Lighting 1200 VA, Receptacles 900 VA, HVAC 2400 VA, Office 600 VA — the sum is 5100 VA. This figure represents total connected load on the panel before any demand factors, diversity, or continuous-load multipliers are applied. It is not a feeder or service load calculation under NEC Article 220; it is the raw nameplate/circuit total that a load calculation would subsequently adjust.

Phase Load Distribution

Single-pole circuits assign their full VA to the phase listed in Phase placement. Two-pole circuits with a combined placement such as A-B split their VA evenly across both phases they occupy — this reflects how a 2-pole (or double-pole single-phase) circuit draws current on two bus phases simultaneously.

Applying that logic to the entered data:

Circuit	Poles	Phase placement	Load (VA)	A	B	C
Lighting	1	A	1200	1200	–	–
Receptacles	1	B	900	–	900	–
HVAC	2	A-B	2400	1200	1200	–
Office	1	C	600	–	–	600
Total			5100	2400	2100	600

This produces the calculator’s reported results: Phase A load 2400 VA, Phase B load 2100 VA, Phase C load 600 VA. The HVAC circuit’s 2400 VA splits 1200 VA to A and 1200 VA to B, which is why A and B carry more than their single-pole assignments alone would suggest.

Average Phase Load and Imbalance Estimate

Average phase load is the connected load divided evenly across the number of phases present:

Average phase load = Connected load ÷ 3 = 5100 ÷ 3 = 1700 VA

The Imbalance estimate measures how far the loaded phases deviate from that average, expressed as a percentage of the average. In this dataset, Phase A sits 700 VA above average and Phase B sits 400 VA above average, while Phase C sits 1100 VA below average. Summing the phases running above average (700 + 400 = 1100 VA) and dividing by the average phase load gives:

Imbalance estimate = 1100 ÷ 1700 × 100 = 64.7059%

A result in this range flags that Phase C is significantly underloaded relative to A and B — a pattern worth reviewing before finalizing circuit assignments, since heavy imbalance increases neutral current on 3-phase 4-wire systems and can affect voltage stability across phases under unequal loading.

Panel Rating and Space Check

Panel rating (100 A) and Panel spaces (42) are reference fields, not automatically converted into a load percentage in this tool’s output — the calculator reports VA totals, not amperage against the bus rating. To relate the 5100 VA connected load to the 100 A bus, that VA must be divided by the appropriate voltage basis (line-to-line for 3-phase, line-to-neutral for single-phase branch loads) separately from this schedule total. Panel spaces should be checked against the sum of pole counts entered (1+1+2+1 = 5 spaces used of 42 available in this example) to confirm the physical breaker layout fits before the schedule is finalized.

Field and Code Limitations

This calculator totals connected VA and distributes it by phase exactly as entered — it does not apply NEC Article 220 demand factors, continuous-load multipliers, motor code-letter adjustments, or diversity factors for dwelling or commercial load calculations. The Connected load and Imbalance estimate are preliminary screening figures for organizing circuit assignments across phases; they are not a substitute for a full feeder or service load calculation, and the phase balance shown does not account for circuits that will not operate simultaneously. Verify actual conductor sizing, overcurrent protection, and demand-adjusted service load against the applicable NEC load calculation method, and confirm any panel schedule against the local AHJ’s submittal requirements before construction.