Panel Schedule Generator
Create a complete electrical panelboard schedule in minutes. Build a breaker schedule for single-phase or 3-phase panels, calculate circuit loads, balance phases, and ensure NEC compliance for electrical distribution panels.
| # | Description | Load (VA) | Voltage | Phases | A | B | C | Breaker | Type | Actions |
|---|---|---|---|---|---|---|---|---|---|---|
Panel schedules are essential for electrical system documentation, load analysis, and NEC compliance. Proper load calculations ensure safe operation and optimal system performance.
Load Calculations
I = P ÷ V (single phase)
I = P ÷ (√3 × V) (three phase)
Demand = Connected Load × Demand Factor
Apply NEC demand factors per load type
Continuous Load × 1.25 + Non-continuous Load
NEC 210.20(A) requirement
Phase Balance Analysis
Imbalance = (Max Load - Min Load) ÷ Max Load × 100%
Should be less than 20%
In = √(IA² + IB² + IC² - IAIB - IBIC - IAIC)
For unbalanced loads
Balance % = 100% - Imbalance %
Target: > 90% for optimal performance
NEC Article 408 - Panelboard Requirements
Construction Standards
- 408.34: Classification - lighting and appliance branch circuit panelboards
- 408.36: Overcurrent protection requirements
- 408.40: Grounding requirements for panelboards
- 408.41: Panelboard identification and circuit directory
Installation Requirements
- 110.26: Working space clearances (3 feet minimum)
- 240.6: Standard ampere ratings for overcurrent devices
- 210.11: Branch circuit required calculations
- 220.40: General lighting load calculations
Example Panel Calculation
200A main panel with mixed loads:
• Lighting: 12,000 VA (continuous) × 1.25 = 15,000 VA
• Receptacles: 8,000 VA (non-continuous) = 8,000 VA
• HVAC: 15,000 VA (continuous) × 1.25 = 18,750 VA
• Total demand load: 41,750 VA
• Current at 208V 3φ: 41,750 ÷ (208 × √3) = 116A
• Panel utilization: 116A ÷ 200A = 58% (good loading)
How to Create a Panel Schedule: Step-by-Step
A panel schedule organizes all circuits in an electrical panel, showing breaker assignments, loads, and phase balance. It is required for permits and essential for troubleshooting.
Step 1: List All Circuits With Their Loads
Document every circuit that will connect to the panel. Include the description (e.g., "Kitchen Receptacles"), breaker size, wire gauge, and the calculated VA load. Group similar circuits together for easy reference.
Step 2: Assign Circuits to Breaker Slots
Place 240V circuits (double-pole breakers) first since they span two slots. Then fill in 120V circuits. Odd-numbered slots connect to Phase A and even-numbered slots connect to Phase B.
Step 3: Balance the Phases
Distribute 120V loads evenly between Phase A and Phase B. Aim for less than 10% difference between phases. Unbalanced panels cause neutral overloading and uneven voltage at receptacles.
Step 4: Sum Loads and Calculate Demand
Add up all connected VA per phase. Apply appropriate NEC demand factors. The total demand determines whether your panel has adequate capacity for the loads.
Step 5: Verify Main Breaker Rating
Divide total demand VA by 240V to get the required amps. This must not exceed the main breaker rating. A 200A panel can handle up to 48,000 VA total demand (200A x 240V).
Formula
Total Panel Load (amps) = Sum of All Circuit Loads (VA) / 240V
Where: Circuit loads are measured in VA (volt-amperes), 240V is the line-to-line voltage for single-phase residential panels
Worked Example
Scenario: Create a panel schedule for a 200A residential panel with 24 circuits.
- Step 1: Circuits include: Range (8,000VA), Dryer (5,000VA), AC (5,000VA), Water Heater (4,500VA), 6 lighting circuits (1,800VA each), 4 receptacle circuits (1,800VA each), 2 kitchen circuits (1,500VA each)
- Step 2: Range, dryer, AC, and WH get 240V double-pole breakers (slots 1-8). Remaining circuits fill slots 9-24
- Step 3: Phase A = 22,100 VA, Phase B = 21,900 VA (balanced within 1%)
- Step 4: Total connected = 44,000 VA. After demand factors: approximately 33,000 VA
- Step 5: 33,000 / 240 = 137.5A. Well within the 200A main breaker
Result: The 200A panel handles all 24 circuits at 137.5A demand, leaving 62.5A of spare capacity for future loads.
3 Phase Panel Schedule: How Phases Are Numbered
In a 3 phase panel schedule, circuits follow an A-B-C phase rotation as you move down the panel. On the left column, circuit 1 lands on Phase A, circuit 3 on Phase B, and circuit 5 on Phase C, then the pattern repeats (7=A, 9=B, 11=C). The right column mirrors it: circuit 2 is Phase A, circuit 4 is Phase B, and circuit 6 is Phase C. Circuits directly across from each other (1 and 2, 3 and 4) share the same phase because they connect to the same bus stab.
This rotation is why balancing matters. If you stack all your lighting circuits in consecutive odd slots without checking the phase column, you can easily overload Phase A while Phases B and C sit nearly empty. Unbalanced phases cause excessive neutral current, uneven voltage at the loads, transformer heating, and nuisance tripping. Aim to keep the connected VA on each phase within about 10% of the others - the calculator above totals each phase automatically so you can shuffle circuits until the bar graph evens out.
208Y/120V Panels
The most common 3-phase panel in commercial buildings. Single-pole breakers deliver 120V for receptacles and lighting, two-pole breakers deliver 208V, and three-pole breakers deliver 208V 3-phase for motors and HVAC equipment. Note that two phases give you 208V, not 240V - a common mistake when specifying equipment.
480Y/277V Panels
Used in larger commercial and industrial facilities. Single-pole breakers deliver 277V, typically for high-bay and fluorescent/LED lighting, and three-pole breakers deliver 480V 3-phase for large motors and chillers. A step-down transformer feeds separate 208Y/120V panels for receptacle loads.
What Belongs on a Panelboard Schedule
A complete panelboard schedule documents everything an electrician, engineer, or inspector needs to know about the panel without opening the cover. NEC 408.4 requires every circuit and circuit modification to be legibly identified as to its clear, evident, and specific purpose - vague labels like "lights" or "outlets" don't meet the requirement. Use this checklist:
- Panel designation - the panel's name or ID (e.g., "LP-1", "Panel A") and its location in the building
- Voltage, phases, and wires - e.g., 120/240V 1-phase 3-wire, or 208Y/120V 3-phase 4-wire
- Main breaker or MLO rating - the main breaker amperage, or "MLO" (main lug only) with the bus rating
- Circuit number - odd numbers on the left, even on the right, matching the physical breaker positions
- Breaker trip rating and poles - e.g., 20A/1P for a receptacle circuit, 50A/2P for a range, 30A/3P for a motor
- Load description - specific and legible per NEC 408.4: "Kitchen counter receptacles" not just "plugs"
- VA per phase - the connected volt-amperes assigned to Phase A, B, and C for each circuit
- Connected and demand load totals - total connected VA per phase, plus the calculated demand load after NEC Article 220 factors
Commercial drawings typically also note the AIC rating, feeder size, and mounting (surface or flush). Print the finished breaker schedule and mount it inside the panel door so it stays with the equipment.
Breaker Panel Sizing: Is Your Panel Full?
A panel is "full" in two different ways: it can run out of physical spaces, or it can run out of load capacity. Count the spaces first - a 200A panel typically has 40 or 42 spaces, and every two-pole breaker consumes two of them. If spaces are gone but capacity remains, tandem breakers can help, but only where the panel is listed for them: check the label for wording like "Maximum 30 circuits" on a 20-space panel, and note that many panels restrict tandems to specific positions or prohibit them entirely.
If the calculated demand load approaches the main breaker rating, adding breakers isn't the answer. When demand exceeds roughly 80-90% of the main rating, plan a subpanel fed from a spare two-pole breaker (for space problems) or a service upgrade to 200A or larger (for capacity problems). Run a full whole house load calculation to see whether your existing service can absorb new loads like an EV charger or heat pump, and use the NEC load calculation tool to apply Article 220 demand factors before sizing a new panel or feeder.
Panel Schedule Questions & Answers
What is a panelboard schedule?
A panelboard schedule is a table that documents every circuit in an electrical panel: circuit numbers, breaker trip ratings and poles, load descriptions, and VA per phase, plus the panel's designation, voltage, phase configuration, and main breaker or MLO rating. It appears on construction drawings for permits, and a printed copy is mounted inside the panel door as the circuit directory required by NEC 408.4.
How do I fill out a 3 phase panel schedule?
List circuits by number - odd on the left, even on the right - and assign phases in A-B-C rotation down the panel: circuits 1, 3, 5 land on Phases A, B, C, and circuits 2, 4, 6 mirror that on the right. Enter each circuit's breaker size, poles, description, and VA, then total the VA per phase. Shift single-pole circuits between slots until all three phases are within about 10% of each other.
Does the NEC require panel schedules?
Yes. NEC 408.4(A) requires every circuit and circuit modification to be legibly identified as to its clear, evident, and specific purpose, with the identification on a circuit directory at the panelboard or on each switch. Vague labels like "lights" or "misc" don't comply - descriptions must be specific enough that someone unfamiliar with the building can identify the circuit. Inspectors routinely check this at final.
What information must be included on a panel schedule?
NEC requires circuit identification, load in amps or VA, circuit breaker size, and wire size. Best practice includes circuit description, phase assignment, and calculated loads. The inspector needs to see that each circuit is properly protected and that the panel isn't overloaded. Missing or incomplete panel schedules are a common cause of inspection delays.
How do I balance loads across phases?
Try to keep each phase within 20% of the others. In a 200A panel, if Phase A has 160A, Phase B should be 128-192A, and Phase C should be 128-192A. Unbalanced loads cause neutral current, voltage variations, and inefficient operation. Large 240V loads (like water heaters) help balance since they use two phases equally.
Can I exceed the panel's main breaker rating?
The total connected load can exceed the main breaker rating, but the calculated load (with demand factors) should not. A 200A panel might have 300A of connected load, but after applying NEC demand factors, the calculated load is 180A. This is normal and acceptable - not everything runs at full load simultaneously.
What's the difference between connected load and calculated load?
Connected load is the sum of all circuit breaker ratings - if you have 40 circuits at 20A each, that's 800A connected. Calculated load applies demand factors from NEC Article 220. Those same circuits might only be 400A calculated load after demand factors. You size the panel feeder for calculated load, not connected load.
How many circuits can I put in a panel?
It depends on the panel's physical spaces and load capacity. A 200A panel might have 40-42 spaces but can't handle 40 circuits at 20A each (800A total). The calculated load is the limiting factor, not the number of spaces. Most residential panels max out on load before running out of spaces.
What's the 80% rule for panel loading?
Continuous loads (3+ hours) must be calculated at 125% of their rating, which means you can only load a breaker to 80% for continuous loads. A 20A breaker can handle 20A non-continuous or 16A continuous loads. This applies to individual circuits, not the entire panel. The panel itself can be loaded to 100% of its rating.
Do I need AFCI and GFCI protection on every circuit?
AFCI is required on most 15A and 20A branch circuits in living areas per NEC 210.12. GFCI is required in bathrooms, kitchens, outdoors, basements, garages, and other wet locations per NEC 210.8. You can use AFCI/GFCI breakers in the panel or GFCI outlets downstream. Mark these protection types on your panel schedule.
How do I handle multi-wire branch circuits?
Multi-wire circuits use a shared neutral between two hot conductors on different phases. They must be on a common trip breaker or have handle ties per NEC 210.4(B). On your panel schedule, show both circuits and note they're part of a multi-wire branch circuit. The neutral carries only the unbalanced current between the two phases.
What spare capacity should I include?
NEC requires 25% spare capacity in dwellings per 210.11(C)(3). For a 200A service, plan for 150A of connected loads max. This gives room for future additions without service upgrades. Commercial buildings don't have this requirement, but 10-20% spare capacity is good practice for future flexibility.
Can I use tandem breakers to add more circuits?
Only if the panel is listed to accept them. Check the panel label - it will say something like "Maximum 30 circuits, 20 single pole" which means 10 tandems are allowed. Don't exceed the maximum circuit count even with tandems. Some panels don't allow tandems at all, especially in certain positions.
What's the difference between a panel schedule and a load calculation?
A load calculation determines the total electrical demand to size the service and main panel. A panel schedule shows how that load is distributed among individual circuits. You do the load calculation first to determine panel size, then create the panel schedule to show how circuits are arranged and loaded within that panel.
What's the most common panel schedule mistake?
Not updating the schedule when changes are made. I see panel schedules from 1995 on panels that have been modified 20 times. Circuits are mislabeled, loads are wrong, and new circuits aren't documented. Keep the schedule current - it's required by NEC 408.4(A) and makes troubleshooting much easier for the next electrician.
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