PanelDexThe formulas
| Number | How it's worked out |
|---|---|
| VA per leg or phase | Sum of the loads on that leg. A 2-pole load counts half on each of its legs; a 3-pole load counts a third on each phase. |
| Approximate amps | 120/240 V: leg VA ÷ 120. 120/208 V: phase VA ÷ 120. 277/480 V: phase VA ÷ 277. |
| Total | Sum of every load you entered. |
| Imbalance | (highest leg − lowest leg) ÷ highest leg, as a percentage. |
A worked example
The example panel that loads with the tool is a 40-space, 120/240 V house panel. Its loads come to L1 18,250 VA (about 152.1 A), L2 17,150 VA (about 142.9 A). The total is 35,400 VA, and the imbalance is (18,250 − 17,150) ÷ 18,250 = 6.0%.
The 8,000 VA range on spaces 3 and 5 adds 4,000 VA to each leg, so it doesn't change the balance. The single-pole circuits are what move it: each one lands entirely on the leg of its row. That's why the editor shows the leg next to every row.
Why legs and phases matter
On a 120/240 V panel, 120 V circuits on L1 and on L2 share the neutral, which carries roughly the difference between the two legs' 120 V loads. Loads spread fairly evenly across the legs keep each leg's current closer to the other. On a three-phase panel the same idea applies across A, B and C. Seeing the totals makes it easy to notice when most of the heavy single-pole circuits have ended up on one leg.
What this is not
These are totals of the loads you entered — not a code load calculation. For sizing a service, feeder or panel, a licensed electrician does an NEC Article 220 load calculation. Article 220 has its own rules, such as standard allowances for general lighting and demand factors for some appliances, and it's applied by someone qualified to size the equipment. Summing connected loads, as this page does, usually gives a different number. Don't use these totals to choose a service size, a feeder or a breaker.
Moving a circuit to another space to balance the legs is work inside the panel. Labelling tool only. Turn power off and follow local code; have a licensed electrician do electrical work.
Getting the numbers in
- Use nameplate ratings where you can. Many appliances list watts; motors and some equipment list amps, which you multiply by the voltage.
- For general receptacle and lighting circuits, enter a figure you're comfortable with as an estimate, or leave the load blank. Blank loads count as zero.
- Enter a 240 V or 208 V appliance's full load once on its 2-pole breaker. PanelDex does the split.
The Excel download keeps the same formulas live: per-pole loads, SUMIF totals per leg or phase, approximate amps and the imbalance, so you can try changes in a spreadsheet as well.
Frequently asked questions
Is this a load calculation for sizing my service?
No. It adds up the numbers you type. Sizing a service, feeder or panel uses an NEC Article 220 load calculation, which has its own rules and demand factors; a licensed electrician does that. Labelling tool only. Turn power off and follow local code; have a licensed electrician do electrical work.
Where do I get the VA for each circuit?
From the equipment: appliance nameplates list watts or amps. Watts are close to VA for heating loads; for others, volts × amps gives VA. Enter the whole load for a 240 V appliance and PanelDex splits it across the two poles.
What imbalance is acceptable?
PanelDex shows the percentage but doesn't judge it. Whether and how to move circuits between legs is a decision for a licensed electrician, who can also check things these totals don't cover.
Why are the amps approximate?
They divide each leg or phase's VA by 120 V (or 277 V). Loads don't all run at once, real power factors vary, and on three-phase panels a 2-pole load draws somewhat more current than the even split suggests.
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Last updated · Written by the Rooh Sites team. General information, not electrical advice.