Diversity Factor 1.39: Why 682 kW Connected Metered at 491 kW Demand
Introduction #
When this guide fits: Someone handed you a spreadsheet with diversity = 0.55 copied from another industry and you need a defensible coincident factor for transformer or main breaker sizing.
When it is not suitable: NFPA 99 healthcare, data center Tier IV, or any site where every load must ride through on nameplate—diversity assumptions differ.
Verified: 2026-05-25 — 30-day utility interval vs nameplate inventory on the packaging campus (load mistakes case).
Two definitions people confuse #
| Term | Formula (this site) | Our measured value |
|---|---|---|
| Facility coincident factor | Connected kW ÷ Demand kW | 682 ÷ 491 = 1.39 |
| Group demand factor | Group demand ÷ Group connected | Varies 0.40–0.95 by group |
Facility coincident factor ≥ 1.0 — higher means more diversity (less simultaneous peak).
Coincident factor = Connected kW ÷ Measured demand kW
= 682 ÷ 491 = 1.39
Do not invert this when speaking to finance—show both numbers side by side.
Meter proof — how we got 1.39 #
| Step | Result |
|---|---|
| Nameplate inventory (connected) | 682 kW |
| Utility 15-min peak (30 days) | 491 kW |
| PQ analyzer cross-check | 488 kW (same week) |
| Coincident factor | 1.39 |
If your factor is below 1.2, either loads truly run together or the inventory missed large motors.
Reproduce demand steps: Factory Load Calculator.
Group demand factors — same plant, by feeder #
These are demand factors (group demand ÷ group connected), not the facility coincident factor:
| Load group | Connected kW | Group demand kW | Demand factor |
|---|---|---|---|
| Packaging lines 1–4 | 420 | 318 | 0.76 |
| Seal welders | 85 | 34 | 0.40 |
| Chillers + pumps | 95 | 72 | 0.76 |
| Lighting + controls | 48 | 44 | 0.92 |
| Offices | 34 | 23 | 0.68 |
Welding at 0.40 pulled the site-wide factor down—but you still must use metered total, not a blended guess.
The 0.55 spreadsheet error (field story) #
An intern applied textile industry 0.55 to 682 kW connected:
Wrong demand = 682 × 0.55 = 375 kW (vs 491 kW actual)
Undersized main → nuisance trips
Correct approach:
Use metered demand 491 kW first
Document coincident factor 1.39 for next expansion
Full trip narrative: Factory load calculation mistakes.
When textbook tables are OK (and when they are not) #
| Situation | Use tables? |
|---|---|
| Greenfield, no meter | Start IEEE/IEEE 141 bands, replace after 60 days |
| Expansion on live plant | Meter first, tables only cross-check |
| Single batch process 24/7 | Low diversity—factor approaches 1.0–1.1 |
| Many intermittent welders | Group 0.35–0.50 possible—but prove it |
| Industry (planning only) | Typical coincident factor band |
|---|---|
| Continuous process | 1.05–1.15 |
| General manufacturing | 1.25–1.45 |
| Job shop / welding heavy | 1.40–1.70 |
Our packaging site at 1.39 sits in the general manufacturing band—not textile 1.8+.
Apply diversity without double-counting #
Wrong:
Apply group factors → sum → apply another 0.85 "whole plant" factor
Right:
Option A: Metered utility peak (preferred)
Option B: Sum of group demands with non-coincident zones (HVAC guide method)
Connected vs demand primer: Connected Load vs Demand Load.
After kW is firm, convert with kW to kVA for transformer work in distribution design.
Browse Power calculator hub.
Related articles #
Next steps you should take #
- Export 30 days of interval kW; record the billing peak window.
- Sum connected nameplates the same week.
- Compute connected ÷ demand; file as coincident factor.
- Split group demand factors only for feeders you submeter.
- Update assumptions after Line 5 expansion (page 2026-05-25).
Is diversity factor the same as demand factor?
People mix them. We use coincident factor for the whole site (682/491) and demand factor per load group (group demand ÷ group connected).
Can coincident factor be less than 1.0?
Not for connected ÷ demand—if your math shows <1, check CT polarity or double-counted nameplates.
How often should we recalculate?
After any line addition, seasonal product change, or shift schedule change—at least annually on industrial tariffs.
Does HVAC diversity match electrical diversity?
No—coincident cooling peaks use zone envelopes ([HVAC design](/guides/industrial-hvac-design)), but electrical demand still needs its own meter proof.
What if I only have nameplates today?
Use conservative group factors, size temporarily, then install metering and rightsizing within 60–90 days—do not lock 0.55 from another industry.