Control Panel Power Calculator

Plan panel loads for pumps, lighting, and controls. See kW, kVA, and current instantly here. Choose breakers with spare capacity and confidence every time.

Inputs

Enter supply details and up to six load groups. Use demand factors for non-continuous loads, then apply a diversity factor for coincident operation.

Typical: 230 (1φ), 400/415 (3φ).
Used for current calculation.
If unknown, 0.85–0.95 is common.
≥1. Higher reduces coincident demand.
Typical: 15–30% for expansion.
Busbars, ventilation, internal wiring losses.
Add coils, relays, PLC, indicators, etc.
Often 125% for continuous loading.

Load groups

Use each row for similar loads. Example: “Motors”, “Lighting”, “Receptacles”, “Heaters”, “HVAC”.

Group 1
100% means fully counted.
Used for documentation; overall PF sets sizing.
Group 2
100% means fully counted.
Used for documentation; overall PF sets sizing.
Group 3
100% means fully counted.
Used for documentation; overall PF sets sizing.
Group 4
100% means fully counted.
Used for documentation; overall PF sets sizing.
Group 5
100% means fully counted.
Used for documentation; overall PF sets sizing.
Group 6
100% means fully counted.
Used for documentation; overall PF sets sizing.
Reset

This tool supports early-stage estimating. Confirm cable sizing, fault levels, and protective coordination with your engineer and standards.

Example data table

Scenario Voltage Phase Loads (summary) Demand kW PF Spare Approx. main breaker
Small pump station panel 400 V 3×1.5 kW motors, 1 kW lighting, 0.2 kW controls 5.50 0.90 20% 16–25 A (verify with code)
Workshop distribution panel 230 V Heaters 4 kW, tools 2 kW, lighting 0.8 kW 6.00 0.95 25% 40–63 A (verify with code)
HVAC control panel 415 V Fans 6 kW, compressors 12 kW, controls 0.5 kW 14.00 0.88 15% 32–50 A (verify with code)

Examples are illustrative only. Final selection depends on duty cycle, ambient conditions, and standards.

Formula used

How to use this calculator

  1. Enter supply voltage and select single-phase or three-phase.
  2. Set an overall power factor that matches your load mix.
  3. Add each load group using quantity, watts each, and demand factor.
  4. Use diversity factor to reflect coincident operation realistically.
  5. Add control transformer VA and a small allowance for losses.
  6. Choose spare capacity for future circuits and upgrades.
  7. Press Calculate to view kW, kVA, current, and breaker size.
  8. Download CSV or PDF for design notes and submittals.

Professional guidance

Load Inventory and Connected Demand

A control panel estimate begins with a disciplined load list. Group similar devices, enter quantity, and use realistic watts per unit. The calculator sums connected kilowatts so you can see the absolute maximum demand. Add auxiliaries like ventilation fans, panel heaters, and network gear. For motors, use electrical input or starter rating, not shaft power. Record any inrush or starting allowances separately for detailed studies.

Using Demand Factors and Diversity

Real sites rarely run every circuit at full output. Apply demand factors to represent duty cycle, then use a diversity factor to model coincident operation across groups. This reduces oversizing while keeping a practical margin for peak periods. Assign higher demand to critical pumps, safety circuits, and process controls. Assign lower demand to intermittent tools and standby loads.

Converting Real Power to Apparent Power

Design selection often depends on kVA and current, not only kW. The calculator converts net kW to kVA using an overall power factor, then computes current from voltage and phase. This supports feeder, incomer, and upstream distribution planning. If power factor correction is planned, rerun with the target value to see the current reduction and spare capacity gains.

Adding Spare Capacity and Continuous Loading

Panels should allow for expansion, ambient heat, and continuous operation. Apply spare capacity to raise design kVA and current for future circuits. Then apply a continuous sizing factor, commonly 125 percent, to estimate a protective device that runs cooler under long duty. The calculator rounds the result to common breaker ratings to speed coordination discussions. Use results as a starting point for cable selection and thermal checks later.

Deliverables for Installation and Review

The result table documents connected load, demanded load, diversified demand, losses, control power, and final design figures. Download files provide traceable records for submittals, internal review, and site coordination. Always verify final selections using local codes, short circuit data, and protective coordination studies. Confirm conductor sizing, enclosure heat dissipation, and manufacturer limits before purchase.

FAQs

1) What is the difference between demand factor and diversity factor?

Demand factor reduces each load group based on expected duty cycle. Diversity factor reduces the combined demand to reflect loads that do not operate together at the same time.

2) Which watt value should I enter for motors?

Use electrical input watts from nameplate, VFD data, or starter rating. If you only know kW output, convert using estimated efficiency and power factor to avoid undercounting.

3) Why does a lower power factor increase current?

Lower power factor means more apparent power is required for the same real power. Higher kVA leads to higher current at the same voltage, increasing heating and voltage drop.

4) How should I choose spare capacity percentage?

Select a value that matches expected expansion and operational flexibility. Many projects start with 15–30 percent, then adjust after stakeholder review and panel space checks.

5) Does this calculator replace short circuit and coordination studies?

No. It estimates operating power and current for sizing discussions. Fault levels, protective coordination, conductor sizing, and equipment ratings must be verified with code-compliant studies.

6) When should I change the continuous sizing factor?

Increase it when the main protection must carry continuous load for long periods. Use your local standard and manufacturer guidance; 125 percent is common for continuous circuits.

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Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.