PanelDexPhase by row: A, B, C
Three-phase panelboards use the same odd-left, even-right numbering as residential panels, but the bus connects each row to one of three phases in turn:
1 ─┤ A ├─ 2 3 ─┤ B ├─ 4 5 ─┤ C ├─ 6 7 ─┤ A ├─ 8 9 ─┤ B ├─ 10 11 ─┤ C ├─ 12 … … …
Because each row is one phase, a column of three spaces always covers A, B and C once each. That's why a 3-pole breaker takes spaces like 1, 3 and 5, and why a 2-pole breaker in 11 and 13 sits on two different phases.
120/208 V and 277/480 V
- 120/208 V: 120 V from any phase to neutral and 208 V between phases. Single-pole circuits feed 120 V receptacles and lighting; 2-pole and 3-pole breakers feed 208 V equipment such as water heaters, rooftop units and motors.
- 277/480 V: 277 V from phase to neutral and 480 V between phases. Single-pole circuits often feed commercial lighting at 277 V; 3-pole breakers feed larger motors and equipment. Ordinary 120 V receptacles are usually supplied from a separate 120/208 V panel fed through a transformer.
Totals per phase
The totals card adds the VA you enter on each phase. A multi-pole load is split evenly across its poles, so a 14,000 VA rooftop unit on a 3-pole breaker counts about 4,667 VA on each phase. Approximate amps are the phase VA divided by 120 V (120/208 V panels) or 277 V (277/480 V panels). For two-pole loads on a three-phase panel, the real current is somewhat higher than this even split suggests, so treat the amps as a rough guide.
For the example panel above, the phases come to A 13,877 VA (about 115.6 A), B 9,827 VA (about 81.9 A), C 10,597 VA (about 88.3 A), a total of 34,300 VA and an imbalance of 29.2%. 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.
A typical commercial schedule
Commercial schedules are usually named after the panel's own designation, such as LP-1 or Panel A, and say which switchboard or panel feeds them. Many branch panels are main lugs only, protected by a breaker at the switchboard. The header block carries all of that, plus the bus rating and the number of spaces, and the circuit table shows breaker rating and poles, wire size and the load on each pole.
The Excel download gives one row per space with the phase in its own column and a per-phase SUMIF total at the bottom, which makes it a reasonable starting point for a 3 phase panel schedule template in Excel that your team can keep updating.
Panels with many circuits
Choose up to 84 spaces. On the PDF, larger panels continue onto a second page with the header repeated, and a 3-pole breaker is never split across the page break. The door directory scales its text to fit the size you choose, and the label sheet fits 64 labels on Letter or 72 on A4.
Labelling tool only. Turn power off and follow local code; have a licensed electrician do electrical work.
Frequently asked questions
How are phases assigned in a 3 phase panel schedule?
By row. Circuits 1 and 2 are on phase A, 3 and 4 on B, 5 and 6 on C, then 7 and 8 back on A, and so on down the panel. Both circuits in a row share the same phase.
Where does a 3-pole breaker go?
In three vertically adjacent spaces of one column, such as 1, 3 and 5, which puts one pole on each of A, B and C. The editor blocks a 3-pole breaker that would run off the bottom of the column or overlap another breaker.
How are amps per phase estimated?
Phase VA divided by 120 V on a 120/208 V panel, or by 277 V on a 277/480 V panel. A 2-pole load on these panels is connected between two phases and draws somewhat more current than this even-split estimate shows.
Can I use this for a 277/480 V lighting panel?
Yes. Choose 277/480 V three-phase. Single-pole circuits on that panel are 277 V, which is typical for commercial lighting. The approximate amps use 277 V.
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Last updated · Written by the Rooh Sites team. General information, not electrical advice.