Phase Balance Across Panels
Per-phase totals, imbalance percent, and a greedy swap list to rebalance.
Example
You enter
- Circuits phase A, load (W) 1500; phase A, load (W) 800; phase B, load (W) 600; phase C, load (W) 700
- Imbalance threshold (%) 10
You get
- Average (W) 1200
- Initial imbalance 141.67 %
- After swaps 66.67 %
No published worked example is on file for this calculation. It is checked against a hand-worked derivation of its method and an independent reference test.
Details, formula, and sources
Formula or tablePer-phase totals, then imbalance % = (max - min) / average x 100. The swap suggestion is a greedy pass that moves the largest circuit that fits under half the gap from the heaviest phase to the lightest. The spread (max - min) / average is about twice NEMA's maximum-deviation-from-average measure (48/52/50 A: 8% here, 4% by NEMA).
Source and editionEngineering practice; NEC Article 220 by name.
Free accessFree read-only access at nfpa.org/freeaccess.
What governsEstimate. AHJ and licensed electrician govern. Verify against the NEC edition adopted in your jurisdiction.
API field namescircuits, threshold_percent, average_W, imbalance_percent, final_imbalance_percent