In short. A load list records every electrical load with its rating and behaviour; a load schedule organises them by board and circuit with demand factors. The quality of generator, transformer and cable sizing depends on it, because errors here carry into every later study.
Fields to capture
| Field | Why it matters |
|---|---|
| Tag and description | Identification and traceability |
| Rated power (kW or kVA) | Basis of demand |
| Voltage, phases | Distribution and balance |
| Efficiency and power factor | Convert shaft kW to input kVA |
| Duty (continuous, intermittent, standby) | Demand and diversity |
| Starting method and current | Motor-starting studies. See starting kVA |
| Load type (linear, non-linear, UPS, VFD) | Harmonics and generator derating |
| Criticality class | Backup priority. See critical-load classification |
| Feeder and board | Loading of each part of the system |
Conversions
For a motor, the electrical input power is the shaft power divided by efficiency, and the apparent power is that divided by power factor.
kVA = kWshaft ÷ (efficiency × power factor)
Building the list
- Start from drawings and equipment schedules, then verify on site.
- Record nameplate values, not assumptions, wherever possible.
- Add measured loads from recordings for existing plant.
- Group loads by board, then by criticality.
- Add future loads with a documented allowance.
- Check phase balance for single-phase loads.
Load schedule outputs
- Connected load per board and total.
- Demand per board with demand factors. See connected, demand and maximum demand.
- Largest motor and starting sequence.
- Critical load subtotal for backup sizing.
Illustrative example
A load list for a small factory has 28 loads. A review shows two 55 kW compressors listed at 45 kW shaft power from catalogue data, while nameplates show 55. The schedule is corrected, raising the connected load and changing the largest-motor starting case used for generator sizing. See load inventory.
Building a load list that survives review
The load list is the first number every other decision rests on. Build it by feeder and by bus, with the essential columns below.
| Column | Why it matters |
|---|---|
| Load name, tag, location | Traceability to site |
| Rated kW (shaft or input) | Basis of demand |
| Efficiency and power factor | Convert kW to kVA |
| Duty: continuous, intermittent, standby | Sets demand factor |
| Starting method and starting kVA | Needed for motor-starting study |
| Critical, essential, normal | Needed for generator-backed supply |
| Nonlinear content | Needed for harmonic and alternator sizing |
Worked conversion (illustrative)
Input kVA = rated kW ÷ (efficiency × power factor)
A 75 kW motor with 93 percent efficiency and 0.86 power factor: 75 ÷ (0.93 × 0.86) ≈ 93.8 kVA. Using 75 kW directly would understate the load by about 20 percent.
Demand factors
Apply a demand factor for loads that never run together, and a diversity factor between groups. Record the reason for each factor. Unexplained factors are the first thing a reviewer challenges.
Future growth
Add a stated margin for expansion, separately from the demand calculation, so it can be adjusted openly.
Check
- Total the list and compare with the metered maximum demand if the site exists.
- Investigate any gap above ten percent.
See connected, demand and maximum demand and generator sizing.
Common mistakes
- Mixing kW and kVA in totals.
- Omitting small loads that add up.
- No distinction between running and starting values.
- No allowance for growth.
What to send us
Send equipment lists and nameplate photographs. Send your application details. See also load study service.
Questions engineers ask
What is the difference between a load list and a load schedule?
The list records loads. The schedule arranges them by board with demand factors and totals.
How much growth allowance should I include?
It depends on the plan. State it explicitly and review it with the owner.
Can I use measured data?
Yes, and it is often better than nameplates for existing plant, if the measurement period covers peak operation.
Why record starting method?
It sets the starting current, which drives generator and voltage-dip studies.
This guide gives general principles. Values must come from your equipment.