The header
The block across the top describes the panel itself. Read it first: every number below depends on it.
- Panel name and location, for example "LP-2A, Electrical Room 204".
- Fed from: the panel or switchboard upstream, and often the breaker in it.
- Voltage and system, for example 208Y/120 V, three-phase, four-wire, or 120/240 V, single-phase, three-wire.
- Bus rating: how much current the panel's bus bars are rated to carry.
- Main: a main breaker size, or MLO for main lugs only.
- Short-circuit rating, in kA: the most current the panel is rated to withstand.
- Mounting: surface or flush.
The circuit rows
Below the header, the schedule lists every breaker position. Odd-numbered circuits run down the left side and even-numbered circuits down the right, so the schedule reads like the panel looks with the door open.
- Circuit number: the position on the panel, not a label someone chose.
- Description: what the circuit serves, in words the next electrician can find in the building.
- Breaker: the trip rating in amps, and the number of poles.
- Load: the circuit's load in VA or kVA, written under the phase it lands on.
- Load type, on many schedules: lighting, receptacles, motors, heating, cooling, kitchen equipment. It decides which demand factor applies.
Poles and phases
On a three-phase panel the bus connections rotate A, B, C down each side. Circuits 1 and 2 land on phase A, 3 and 4 on phase B, 5 and 6 on phase C, and the pattern repeats.
A one-pole breaker takes one position and one phase. A two-pole breaker takes two positions in a row and two phases, and a three-pole breaker takes three positions and all three phases. That is why a three-pole load shows a number in each of the A, B and C columns.
Spares and spaces
A spare is a breaker that is installed but serves nothing yet. A space is a position with no breaker in it. Neither carries load, but a spare can take a new circuit today, and a space needs a breaker first.
The totals
- Connected load per phase, and in total: every circuit added up at full value.
- Demand load: the connected load after the NEC Article 220 demand factors. Sizing the feeder and the main starts from it, with continuous loads taken at 125% (NEC 2023 § 215.2(A)(1) and § 215.3).
- Amps per phase: the load on each phase as a current, to compare against the bus rating and the main.
A well-balanced panel carries about the same load on each phase. When one phase reads far higher than the others, that phase reaches the bus rating first.
When the schedule does not match the panel
Most schedules in a working building are out of date somewhere. Look for descriptions that name rooms that no longer exist, totals that do not add up to their rows, hand-written corrections over the print, and breakers in the panel that the schedule calls spaces.
From a photo to a working schedule
If the schedule you are reading is a photo, a scan or a print, you can start from it as it is.
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AI Import
Upload a photo of a panel schedule. Circuits, breakers and loads come back as an editable schedule, with the source photo one click away.
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Capacity, headroom, utilization and phase balance on every panel.
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Demand, done the NEC way
Each load sorted into its NEC category, with the right demand factors applied: lighting by occupancy, receptacles over 10 kVA, kitchens, the largest motor and compressor. Upstream, demand is recalculated over everything below it.
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Print
PDF panel schedules, ready to hand over or tape inside a door.
Questions
- What is the difference between a spare and a space on a panel schedule?
- A spare is a breaker that is installed but serves nothing yet. A space is a position with no breaker in it. A spare can take a new circuit today. A space needs a breaker first.
- Why are odd circuits on the left and even circuits on the right?
- Breakers sit in two columns down the bus. By convention the left column is numbered 1, 3, 5 and the right column 2, 4, 6, so circuits 1 and 2 sit side by side on the same bus bar.
- What does MLO mean on a panel schedule?
- Main lugs only. The panel has no main breaker of its own. The breaker upstream that feeds it protects it.