Construction Electrical Load Inputs
Formula Used
Lighting load = floor area × lighting watts per square meter ÷ 1000.
Weighted load = continuous load × 1.25 + motor load × 1.25 + all other listed loads.
Demand load = weighted load × demand factor ÷ 100.
Diversified load = demand load ÷ diversity factor.
Design load = diversified load + future reserve load.
Single phase current = design kW × 1000 ÷ voltage ÷ power factor.
Three phase current = design kW × 1000 ÷ 1.732 ÷ voltage ÷ power factor.
Voltage drop uses conductor resistivity, current, feeder length, conductor area, and phase type.
How to Use This Calculator
- Select the system phase and enter the service voltage.
- Add all known construction loads in kilowatts.
- Enter floor area and lighting watts per square meter.
- Set demand, diversity, reserve, and breaker margin values.
- Add panel rating, feeder length, conductor material, and area.
- Press the calculate button to view results above the form.
- Use CSV or PDF buttons to save the report.
Example Data Table
| Load Type |
Example Value |
Use in Analysis |
| Continuous lighting |
18 kW |
Multiplied by 125 percent |
| Motor load |
10 kW |
Multiplied by 125 percent |
| HVAC load |
14 kW |
Added to weighted load |
| Panel rating |
160 A |
Compared with design current |
| Feeder length |
45 m |
Used for voltage drop |
Electrical Load Planning for Construction
Electrical load analysis gives a project team a practical view of power demand before equipment is bought or installed. It combines connected loads, demand factors, phase selection, power factor, feeder length, and panel capacity. The result is not a permit design by itself. It is a planning worksheet that helps owners, engineers, estimators, and site teams compare options early.
Why Load Analysis Matters
Construction projects often grow after the first estimate. New lighting rows, pumps, tools, lifts, HVAC units, and tenant equipment can change the final service size. A load study reduces surprises. It shows the expected current, the reserve left in the panel, and the likely voltage drop at the far end of a feeder. These figures support clearer budgets and better coordination.
Demand and Diversity
Not every device runs at full output at the same time. Demand factor lowers the connected load to a realistic maximum. Diversity factor recognizes that different load groups peak at different moments. Continuous loads are treated more carefully because they stay on for long periods. Motors are also highlighted because starting and running requirements can affect feeder choices.
Feeder and Panel Review
The calculator estimates current for single phase and three phase systems. It also checks the panel rating against the calculated load. A high utilization value warns that the panel may have little spare capacity. The voltage drop estimate uses conductor material, length, area, and current. Long feeders or small conductors can produce poor performance, even when the panel rating looks acceptable.
Best Use on Site
Use the calculator during concept planning, tender checks, temporary power studies, and change reviews. Enter conservative numbers when exact loads are unknown. Compare several scenarios before selecting equipment. Keep exported reports with project records. Always confirm final conductor, protection, grounding, and code requirements with a qualified electrical professional before installation.
Reading the Result
Review each result as a signal, not a final approval. If voltage drop is high, increase conductor area or shorten the run. If utilization is high, add capacity or split loads. If reserve is low, plan future circuits early. Good records make later revisions faster and safer for every trade involved. It also improves handover clarity for owners.
FAQs
What is electrical load analysis?
It is a review of connected power, demand, current, voltage drop, and panel capacity. It helps plan feeders, panels, circuits, and reserve space before construction work reaches installation.
Is this calculator suitable for final design approval?
No. It supports planning and estimating. Final electrical design must follow local codes, utility rules, equipment data, and professional engineering review where required.
Why are continuous loads multiplied by 125 percent?
Continuous loads run for long periods. The added allowance gives a safer planning margin for conductors, panels, and protective devices during extended operation.
What does demand factor mean?
Demand factor reduces the weighted connected load to a likely maximum operating load. It reflects that many devices are not always used together at full rating.
What does diversity factor do?
Diversity factor accounts for different load groups peaking at different times. A higher value lowers the estimated maximum demand in this calculator.
Why is voltage drop important?
High voltage drop can reduce equipment performance and increase heating. It becomes important on long feeders, heavy loads, and small conductor sizes.
How are branch circuits estimated?
The calculator divides final design load by the usable branch circuit capacity. It uses branch voltage, branch amp rating, utilization percent, and power factor.
Can I export the result?
Yes. Submit the form normally for on-page results. Use the CSV or PDF buttons to download a simple project report.