Maximum demand in Australian load planning
How maximum demand differs from connected load and why Australian switchboard demand checks need method, source and assumptions.
What maximum demand means
Maximum demand is a load-planning value for the demand a switchboard, supply or installation section may need to carry. It is related to connected load, but it is not automatically the same number. Australian maximum-demand work sits beside AS/NZS 3000 context, project requirements and DNSP conditions without this page reproducing controlled tables.
The value depends on load groups, duty, diversity, demand factor assumptions and the method chosen for the project. A calculator can organise entered values, but it does not choose the regulatory or project method for a real installation.
Connected load and demand are not the same
Connected load is the sum or list of loads attached to a board or installation section. Maximum demand is the demand value carried forward after the chosen method and assumptions are applied. Single-phase rows may use a 230 V line-to-neutral basis, while three-phase rows may use a 400 V line-to-line basis.
That distinction matters in Australian switchboard and supply discussions. A demand result without its method, load groups and exclusions can be mistaken for a universal capacity statement.
| Item | Keep visible | Why it matters |
|---|---|---|
| Connected load | Load rows, units and source. | Shows the starting point before demand assumptions. |
| Diversity or demand factor | Entered contribution, duty or factor basis. | Separates connected load from demand value. |
| Board or supply context | MSB, DB, tenancy board or installation section. | Keeps the demand value tied to the correct location. |
| Method source | Project method, authority requirement or design basis. | Separates a worksheet estimate from a controlled design decision. |
Example worksheet reading
| Field | Example entry | Practical reading |
|---|---|---|
| Board or section | Main switchboard or DB-1. | The demand value belongs to this location. |
| Load group | Lighting, socket outlets, EV charger or equipment group. | The group must be traceable to the load schedule. |
| Connected load | 24 kVA connected kVA total with L1/L2/L3 row source. | The starting value should keep its unit source. |
| Demand assumption | 70 percent demand factor entered for the worksheet. | The result depends on the assumption selected. |
| Demand current | Demand current calculated from the voltage and phase basis. | Maximum phase current and available capacity need separate review. |
| Method source | Project requirement, authority context or design basis. | The calculator does not decide the method. |
Use the maximum-demand calculator when the load groups and assumptions are ready. Use the load schedule fields table first when the rows are still being organised.
If phase totals are part of the review, keep L1, L2 and L3 demand values visible. A balanced three-phase demand value and a highest-phase single-phase value answer different questions.
Next checks
- If the load list is incomplete, finish the load schedule before calculating demand.
- If single-phase rows are spread across a three-phase board, check phase balancing separately.
- If spare switchboard capacity is being reviewed, keep demand, existing load and future allowance in the same worksheet.
- If the result affects installation capacity, supply approval, wiring or protection work, keep licensed maximum-demand assessment and current authority requirements in control.
Boundaries
- A maximum-demand worksheet does not choose a regulatory demand method.
- It does not reproduce controlled demand tables.
- It does not approve supply capacity, switchboard capacity or connection work.
- Project documents, authority requirements, engineering review, DNSP conditions and current rules context remain controlling sources.