Paste the panel load list to spread loads across the phases and see each phase and neutral current, the unbalance and the current the feeder and main breaker must carry.
Pre-sizing and estimating tool: results do not replace design, calculations or reports signed by a licensed professional, nor verification against the applicable codes and standards.
Demand kVA on each phase, split into three-phase, line-to-line (half on each phase) and single-phase loads.
Currents from phasor addition, taking each phase angle and each load power factor into account.
Phase of each load (entered or chosen by the calculator), demand and current.
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It is the table listing the circuits of a panelboard with load, number of poles, the phase each one is on and the total per phase. It is used to size the feeder, the main breaker and the transformer, and to keep phases balanced. Use this calculator when laying out a new panel or adding loads to an existing one.
One row per load: description, real power in kW, number of phases (1, 2 or 3), power factor, demand factor in % and, if known, the phase. Copy straight from your spreadsheet or download the template. For motors, use input power (rated ÷ efficiency) and nameplate power factor.
The 13 example loads total 63 kVA of demand (57.9 kW) at 208 V. The most loaded phase carries about 185 A, and that is what sizes the feeder and main breaker; unbalance is 6%, under the 10% limit. The neutral carries only about 18 A because the 120 V loads split evenly.
NEC Article 220 gives demand factors for some loads, for example 220.44: receptacle loads at 100% for the first 10 kVA and 50% above that. Process motors and ovens are usually 100%. For existing panels, a month of metered peak demand (NEC 220.87) is the best basis.
The NEC sets no number for panel balance. Many designers aim for no more than 10% between the most loaded phase and the average, the default here, which you can change. High unbalance forces an oversized feeder and raises neutral current.
Because the three phases are 120° apart: equal currents on the three phases cancel on the neutral, and only the difference returns on it. The exception is third-harmonic current from electronic loads, which adds on the neutral instead of cancelling.
It does not apply NEC demand factors automatically, ignores harmonics and spare capacity, and does not size branch circuits. Take the feeder current to the wire size and breaker calculators, and have the final design reviewed by a qualified engineer.
Important notice: Indus Metrics tools produce estimates and pre-sizing results from the data you enter and from published engineering methods. They do not replace design, calculations or reports signed by a licensed professional engineer (PE), nor verification against the applicable codes, standards and regulations, such as OSHA rules and the ASME codes. Material and fuel properties vary: check manufacturer data or your own process analyses before deciding. By using this site you agree to the Terms of Use.
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