Introduction #

When this guide fits: A stakeholder says “we have 682 kW, size for that” while the utility bill shows a lower 15-minute peak—and you need one slide that explains which number feeds transformers, mains, and tariffs.

When it is not suitable: Branch circuit ampacity for a single motor feeder—use NEC branch rules, not facility demand concepts.

Verified: 2026-05-25 — packaging campus figures used across load mistakes, diversity factor, and distribution one-line.

Connected load higher bar than demand load bar682 kW connected491 kW demand

Definitions — one facility, two numbers #

Term Meaning This plant
Connected load Sum of equipment nameplate kW (everything on at 100%) 682 kW
Demand load Utility billing peak (or metered coincident max) 491 kW
Gap Connected − Demand 191 kW (28%)

Connected is the inventory ceiling. Demand is what actually sets transformer % load, main breaker heat, and demand charges.

Inventory table — where 682 kW came from #

Equipment Qty kW each Connected kW
Form/fill lines 4 85 340
Seal welders 6 8 48
Compressors 2 45 90
Chillers (nameplate) 2 55 110
Lighting + controls — — 52
Offices + misc — — 42
Total connected 682

Demand load is not this table times one magic factor—it is the metered peak below.

Demand proof — where 491 kW came from #

Source Peak kW Window
Utility bill (billed demand) 491 15-min, Mar 2026
PQ analyzer MSB 488 Same week
Intern spreadsheet (wrong) 375 682 × 0.55 ❌

Coincident factor: 682 ÷ 491 = 1.39 — see diversity factor guide.

Sizing comparison — wrong vs right number #

Equipment Sized on 682 kW (wrong) Sized on 491 kW @ PF 0.82 (right)
Apparent power 682 kVA (PF=1 error) 599 kVA
Transformer ordered 750 kVA (overspend story) 750 kVA OK with margin
Main breaker guess 900 A 800 A
Annual extra loss (transformer idle) ~$1.8k Baseline

PF-aware kVA: kW to kVA Calculator. Full walkthrough: Factory Load Calculator.

Cost of picking connected (field dollars) #

Outcome Approx. impact
Oversized transformer capital $8,200
PF=1 on 491 kW → 500 kVA underrun $15,400 downtime (mistakes)
Fantasy 375 kW demand Nuisance trips + scrap

Who uses which number #

Decision Use connected Use demand
Transformer / main kVA ✓
Utility demand charge ✓
Branch breaker to one motor ✓ (nameplate × rules)
“How big is my building?” story ✓
Energy kWh estimating blend ✓ for peak kW

Tariff lines: Energy cost optimization.

Worked conversion — demand to main amps #

kW  = 491
PF  = 0.82
kVA = 491 ÷ 0.82 = 599

I = 599,000 ÷ (√3 × 480) ≈ 720 A
→ standard main 800 A

Check feeders with Breaker Size Calculator.

Distribution context: Electrical distribution design. Browse Power calculator hub.

Next steps you should take #

  1. Build the connected inventory table in kW.
  2. Pull utility 15-min peak for the same month.
  3. Size transformers/mains on demand kVA, not connected.
  4. File both numbers in the project memo—prevent “682 kW” shorthand in bids.
  5. Request GSC re-index after edits (2026-05-25).
Can I add 20% margin to connected load instead of using demand?

No—that double-counts conservatism. Apply margin to metered demand kVA, documented in the safety margin guide.

Why is demand lower than connected if everything runs?

Machines rarely hit nameplate simultaneously; some are standby, cycling, or on reduced settings—the **191 kW gap** is normal here.

Does connected load matter for permits?

Yes—for **service entrance paperwork** and arc-flash inventory—but operating sizing still follows demand for mains.

What if demand exceeds connected?

Investigate **meter CT errors**, **missing nameplates**, or **power factor/reactive** billing registers—not true demand above inventory.

How do I explain this to non-engineers?

Connected is everyone’s max badge added up; demand is what the meter saw on the worst 15 minutes—you bill and size mains on the second.