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Three-Phase Electrical Panel Load Balancing Calculator

Check the load imbalance percentage across a three-phase panel's phases A, B, and C.

Computed in your browser — nothing you enter is uploaded. Figures are presented for United States against IRC 2024, and every formula is cited under regulatory standards below.

Last verified 2026-08-26 · v1.0.0

Market
Imperial · sales tax

Phase load imbalance

9.76 %

High confidence
Average phase load
41 A

Running these inputs gives 9.76 % as the phase load imbalance. Currently reading for United States under IRC 2024 — pick a different market above and the figures re-cast accordingly.

Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — confirmed fixes become pinned regression tests.

[Schema Verified] Computed in alignment with American Concrete Institute (ACI 318-19) formulas and International Residential Code (IRC 2024) spatial boundaries.

Regulatory standards & verification citations

  • Phase imbalance percentage = (maximum deviation from average phase load ÷ average phase load) × 100, the standard method for checking how evenly a three-phase panel's circuits are distributed across its phases

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Frequently asked questions

Why does phase balance matter on a three-phase panel?
An unevenly loaded panel wastes capacity on the lightest phase while pushing the heaviest phase closer to its limit, and can cause uneven voltage drop and neutral current issues — spreading circuits evenly across phases A, B, and C keeps the system operating efficiently and within its rated capacity.
How is the imbalance percentage calculated?
It's the maximum deviation of any single phase from the average of all three phase loads, divided by that average, expressed as a percentage — the standard method for checking how evenly circuits are distributed across phases.
What's considered an acceptable imbalance?
Common guidance targets keeping phase imbalance under roughly 5-10%, though the acceptable threshold can vary by equipment and application — check your specific equipment manufacturer's requirements and local code for any applicable limit.