Example data table
Use this sample set to see how diversity changes when loads rarely peak together.
| Load | Connected (kW) | Demand factor | Individual max (kW) |
|---|---|---|---|
| Tower crane | 45 | 0.60 | 27.0 |
| Site lighting | 12 | 0.85 | 10.2 |
| Temporary HVAC | 30 | 0.70 | 21.0 |
| Welding outlets | 25 | 0.50 | 12.5 |
| Sum of individual max | 70.7 kW | ||
| System maximum demand (example) | 50.0 kW | ||
| Diversity factor | 70.7 / 50.0 = 1.414 | ||
Formula used
Diversity Factor measures how likely loads peak at the same time:
- Individual Max Demand = Connected Load × Demand Factor
- Sum of Individual Max Demands = Σ(Individual Max Demand)
- Diversity Factor = Σ(Individual Max Demand) ÷ (System Maximum Demand)
- Coincidence Factor = 1 ÷ (Diversity Factor)
In practice, you can use measured peak demand for the whole system, or a well-justified estimate based on operating schedules, construction phases, and equipment duty cycles.
How to use this calculator
- Choose a consistent unit (kW, kVA, or A).
- Enter connected load for each circuit or equipment group.
- Apply a demand factor for realistic peak contribution.
- Enter the system maximum demand (measured or estimated).
- Click Calculate to view diversity and coincidence factors.
- Download CSV or PDF for estimates, audits, and submittals.
Tip: If the diversity factor is very close to 1, your peaks are highly coincident. If it is well above 1, you may avoid oversizing upstream equipment.
Professional notes on diversity factor for construction power
1) Why diversity factor matters on active job sites
Construction electrical systems rarely see every connected load peak simultaneously. A tower crane, welders, temporary HVAC, hoists, lighting, and water pumps cycle with different duty patterns. Diversity factor captures that non‑coincidence so you can size feeders, switchgear, and generators more realistically while maintaining safe margins.
2) Key quantities used by this calculator
For each load, the calculator estimates an individual maximum demand by multiplying connected load by a demand factor. Summing those individual maxima gives a conservative “all peaks together” total. The system maximum demand represents your measured or estimated peak for the entire installation during the same period.
3) Typical construction load behavior and seasonality
Morning startups can create short peaks when multiple crews energize tools and lighting. Midday peaks often come from cooling loads, compressors, and material handling. In colder months, heating and dehumidification may replace cooling as the dominant contributor. Track phase-by-phase changes as the project progresses.
4) Selecting demand factors with defensible assumptions
Demand factors reflect expected simultaneous utilization. Intermittent equipment (cranes, hoists, pumps) often uses lower values than continuous loads (lighting, safety systems). If a load is scheduled or controlled, match the factor to its expected duty cycle. Document the basis so estimates remain auditable.
5) Reading the outputs and what “good” looks like
A diversity factor near 1.0 suggests peaks are highly coincident and upstream capacity may need to follow the sum closely. Values above 1.2 commonly indicate meaningful non‑coincidence. The coincidence factor, being the inverse, summarizes how much of the summed maximum demand is expected to occur together.
6) Translating results into feeder and generator sizing
Use system maximum demand as a starting point for practical sizing, then add contingency for growth, motor starting, and harmonic considerations. For generators, include step‑load capability and transient response. For feeders and protection, verify conductor ampacity, voltage drop, and coordination under realistic peaks.
7) Improving accuracy with measurements and short‑interval logging
If you have meter data, select a peak window that matches your planning horizon (daily peak, weekly peak, or a defined shift). Short interval logs (for example 5–15 minutes) reveal true demand peaks better than monthly bills. Update demand factors after major equipment changes or phase transitions.
8) Common pitfalls and quality checks before sign‑off
Avoid mixing units across rows, double‑counting shared loads, or applying factors above reasonable limits. Confirm that the system maximum demand is for the same set of loads included in the table. Finally, review the exports so estimates, procurement, and safety teams are aligned on one consistent basis.
FAQs
1) What is the diversity factor in simple terms?
It is the ratio of summed individual maximum demands to the system maximum demand. It shows how much load non‑coincidence reduces the real peak compared to “all peaks at once.”
2) How is it different from demand factor?
Demand factor is applied to a single load or group to estimate its maximum contribution. Diversity factor compares the sum of those maxima against the whole‑system peak.
3) Can diversity factor be less than 1?
It is usually at least 1. If it drops below 1, recheck inputs: system maximum demand may be too high, or individual maxima may be underestimated or missing loads.
4) What should I use for system maximum demand?
Use measured peak demand from a meter when available. Otherwise, estimate from schedules, equipment duty cycles, and known peak operating conditions for the same load set.
5) Why does the calculator show coincidence factor too?
Coincidence factor is the inverse of diversity factor. It expresses what fraction of the summed maximum demand is expected to occur at the same time.
6) How many loads can I include?
The calculator supports up to 12 loads for fast site planning. If you have more, group similar circuits into logical blocks and apply a justified demand factor for each block.
7) Are the CSV and PDF exports identical?
They contain the same calculation results and load table. CSV is best for spreadsheets and takeoffs, while PDF is convenient for sharing, printing, and attaching to submittals.