Maximum demand worksheet
Build an Australian maximum-demand worksheet from entered load rows, phase allocation and user-entered demand factors.
Irow = entered A, (kW x 1000 / PF) / VLN, (kW x 1000 / PF) / (sqrt(3) x VLL), (kVA x 1000) / VLN, or (kVA x 1000) / (sqrt(3) x VLL); Idemand_row = Irow x Qty x DF; Imax = max(IL1, IL2, IL3) or single-phase IL1; Sdem = sum(row kVA x DF); spare_A = available_A - Imax- Demand factors are user-entered worksheet assumptions.
- Capacity remaining is a comparison value, not an authority decision.
| Variable | Meaning | Unit | Use |
|---|---|---|---|
| Irow | Connected current for one row | A | Entered directly or calculated from kW/PF or kVA. |
| VLN | Line-to-neutral voltage | V | Default 230 V for single-phase row conversion. |
| VLL | Line-to-line voltage | V | Default 400 V for balanced three-phase row conversion. |
| PF | Power factor | decimal | Used when a kW row is converted to apparent power and current. |
| Qty | Quantity | items | Multiplies identical items in a row. |
| DF | Demand factor | % | Entered worksheet assumption applied to the connected row load. |
| IL1/IL2/IL3 | Phase demand currents | A | Used to identify the highest phase on a three-phase worksheet. |
| Imax | Maximum demand current | A | Primary worksheet result from the entered rows. |
| Sdem | Total demand apparent load | kVA | Sum of row demand kVA values. |
| spare_A | Capacity comparison margin | A | Available capacity minus Imax when a comparison value is entered. |
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Maximum demand worksheet technical guide
Build an Australian maximum-demand worksheet from entered load rows, phase allocation and user-entered demand factors.
Where maximum-demand worksheets fit in the job
Maximum-demand work usually starts with a board reference and a load schedule, not with a bare current value. A contractor or estimator may be pricing a tenancy split, an electrician may be checking a board alteration before adding plant, and an engineer may need a traceable demand current before a submain or consumer mains review. The worksheet is useful only when the rows behind the number can be checked.
Use the page as a working schedule for Australian 230/400 V, 50 Hz projects. Record the switchboard, tenancy, meter, distribution board, drawing or load-schedule reference before the result is carried into a design note, tender allowance or site review. Without that reference, a demand result is hard to defend because another reviewer cannot tell what the current belongs to.
The calculator turns entered rows into a worksheet result. It does not decide which demand factor is correct for the installation, reproduce AS/NZS demand tables, select switchgear, decide a supply connection or produce a final installation record. The useful output is the record: row source, phase allocation, quantity, power factor, entered demand factor, phase demand, total demand kVA and maximum phase current.
A 63 A result from measured loads is not the same evidence as a 63 A result made from concept allowances. The arithmetic can match while the basis is completely different. Treat the number as a pointer to the next review, not as a standalone capacity decision.
Load row evidence
Build the worksheet from rows another person can trace. The row source determines whether the result is suitable for estimating, design review, a DNSP discussion, or only early planning. Keep actual loads, future allowances, tenant allowances and spare capacity allowances separate so the basis does not blur later.
| Row source | Good use | Main risk | Record with the result |
|---|---|---|---|
| Existing DB schedule | Board alteration, tenancy split or maintenance review | Circuit names may not match real connected equipment | Board name, circuit number, phase and schedule date |
| Nameplate or manufacturer data | Plant, charger, lift, pump, HVAC or process equipment row | Output rating, duty rating or control mode may not equal electrical input | Model, rating type, voltage, phase, duty and operating mode |
| Measured current or metering | Existing-site capacity review | Measurement interval may miss the design case or seasonal peak | Meter source, date, interval, load state and operating conditions |
| Project load schedule | Design or tender review | Revision may be stale or diversity may be handled elsewhere | Drawing or schedule revision, row ID and author |
| kW or kVA allowance | Estimating before final equipment data | Power factor, quantity or duty may be assumed | Assumption owner, project stage and replacement trigger |
| Future load or spare allowance | Board-capacity and tenancy-capacity discussion | Allowance can be mistaken for connected load | Reason for allowance and when it must be reviewed |
| EV charger row | Charger addition or load-management review | Charger data, control strategy and DNSP conditions may govern the final decision | Charger rating, phase, management basis and DNSP/design check |
The worksheet accepts A, kW or kVA because real schedules arrive in mixed forms. A current value may come from a circuit schedule, a kW value may come from equipment data, and a kVA value may come from a UPS, inverter, transformer or allowance. The calculator can convert the row, but it cannot prove that the source value is the right project value.
Demand factor basis matrix
Demand factors are deliberately entered by the user. This page does not supply hidden Australian rules or a universal table. That is intentional because maximum-demand factors depend on the installation context, load type, project documentation, current requirements and professional judgement.
| Factor basis | Best use | Weak when | Record or check |
|---|---|---|---|
| Current project method | Design worksheet or issued load schedule | Method is not tied to the actual row | Keep the method reference with the row |
| Verified standards process | Formal maximum-demand assessment | The user cannot verify the current requirement | Check the authorised source before relying on it |
| Measured load profile | Existing installation review | Load state, season or operating cycle is not representative | Record the measurement period and basis |
| Manufacturer or controls data | Equipment with managed demand | Controls, duty or operating mode may change | Check the product documentation |
| Tender or concept assumption | Budgeting before final data is issued | Assumption may become final by accident | Mark as preliminary and set a replacement trigger |
| Load-management allowance | EV, plant or controlled-load review | Control strategy may not be accepted, configured or commissioned | Check DNSP, manufacturer and project requirements |
A factor is not stronger because it is typed into a calculator. It becomes stronger when its source is visible and suitable for the decision being made.
Worked Australian examples
Three-phase workshop schedule
A workshop DB worksheet includes one balanced three-phase equipment row and one single-phase row on L2. The board reference is Workshop DB-1, the schedule is under review for an alteration, and the available-capacity comparison entered for the worksheet is 100 A. The three-phase equipment is entered as 30 kW at 0.85 PF with an 80 percent user-entered demand factor. The L2 workshop row is entered as 20 A with a 100 percent factor.
The three-phase row contributes about 40.75 A to each phase after the entered factor is applied. The L2 row adds 20 A to L2, so the worksheet shows about 40.75 A on L1, 60.75 A on L2 and 40.75 A on L3. The maximum demand current from the entered worksheet is 60.75 A.
The immediate finding is that L2 sets the worksheet result. Before using 60.75 A for switchboard or cable work, check the load-schedule revision, the factor source for the 30 kW equipment row, and the basis of the 100 A comparison value.
Single-phase tenancy worksheet
A small single-phase tenancy worksheet is being prepared before final equipment data is issued. The tenancy reference is recorded with the quote, a 32 A row is entered from the draft circuit schedule, and a 6 kW equipment allowance is included at PF 0.80 with a 60 percent entered factor. The available-capacity comparison is 80 A.
The 32 A row contributes 32 A. The 6 kW row converts to about 32.61 A before the factor is applied, so its demand contribution is about 19.57 A. The maximum demand current is 51.57 A, leaving 28.43 A against the entered 80 A comparison value.
That margin is useful for the estimate, but it is not a board-capacity decision. The next check is whether the 6 kW allowance is still current, whether the tenant has additional future loads, and whether the 80 A comparison value is tied to a real supply or design threshold.
EV addition review
A three-phase board review includes an existing balanced load, a 32 A single-phase EV charger row on L1 and a 16 A future allowance on L2. The board reference, charger rating and load-management basis are recorded before the result is exported. The existing load is entered as 24 kW at PF 0.88 with an 80 percent entered factor, and the available-capacity comparison is 100 A.
The existing balanced row contributes about 31.49 A to each phase. The EV row lifts L1 to about 63.49 A, while the future allowance lifts L2 to about 47.49 A. L3 remains about 31.49 A. The maximum demand current from the entered worksheet is therefore 63.49 A.
The worksheet shows that the EV row makes L1 the controlling phase. It does not decide charger acceptance, load management, DNSP conditions, installation requirements or manufacturer instructions. Use the EV charger load calculator when the charger row itself needs to be built from rating and usage assumptions.
Minimum export record
Export only after the worksheet has a valid result and a traceable project reference. The PDF should be a compact calculation record, not a substitute for the project file.
| Record item | Include in or beside the export | Why it matters |
|---|---|---|
| Project reference | Switchboard, tenancy, drawing, load schedule or alteration reference | Ties the current to a real asset or project scope |
| Supply and voltage basis | Single-phase or three-phase worksheet, 230 V line-to-neutral and 400 V line-to-line where used | Lets another reviewer understand the conversion basis |
| Row evidence | Row labels, source type, phase allocation, quantity, PF and demand factor | Shows whether the result came from measured loads, nameplate data, schedule rows or allowances |
| Result summary | Maximum phase current, phase demand currents, total demand kVA and connected kVA | Carries the useful calculation values into downstream checks |
| Capacity comparison | Entered available-capacity value and remaining margin where used | Keeps the comparison separate from any authority or design decision |
| Reviewer | Electrician, engineer, estimator or reviewer name | Makes the exported record traceable to a named reviewer |
Review workflow
| Step | Worksheet action | Evidence to keep | Result check |
|---|---|---|---|
| 1. Identify the board or tenancy | Name the switchboard, tenancy, meter, distribution board or schedule reference | Drawing, site label, schedule revision or quote reference | The result belongs to a defined asset or project scope |
| 2. Separate the load inventory | Split actual loads, future allowances, tenant allowances, EV rows and spare allowances | Row source and reason for inclusion | Allowances are not mistaken for installed load |
| 3. Select the row basis | Enter A where current is known, or kW/PF or kVA where that is the available source | Nameplate, schedule, meter export, equipment list or estimate | Connected current and connected kVA are traceable |
| 4. Allocate phase loading | Put each single-phase row on L1, L2 or L3; leave balanced three-phase rows as three-phase | Phase marking, circuit schedule or proposed connection | The highest phase is meaningful |
| 5. Enter the demand factor | Use the factor adopted for that row outside the calculator | Project method, authorised source, measured profile or design assumption | The factor can be defended or replaced |
| 6. Review spare capacity | Compare only against a known board, supply or design threshold | Main switch, design limit, supply advice or project criterion | A negative value triggers review; a positive value does not settle suitability |
| 7. Carry the result forward | Record maximum phase current, total demand kVA and source basis | Exported worksheet or design record | Downstream checks know what was assumed |
This workflow keeps the calculator in the right role. It handles arithmetic and record discipline. It does not replace standards review, DNSP discussion, switchboard design, protection review, cable sizing or final verification.
| Worksheet result | What it suggests | Check next | Do not conclude |
|---|---|---|---|
| One phase is clearly highest | Single-phase allocation or a major row may be driving the demand | Phase allocation, load schedule and whether phase-balancing review is needed | The load should be moved automatically |
| Capacity remaining is positive | The entered comparison value is above the worksheet current | Source and rating basis of the comparison value | The board, supply or consumer mains is suitable |
| Capacity remaining is negative | The worksheet current exceeds the entered comparison value | Demand-factor basis, row sources, supply capacity, DNSP/network requirements and design options | The only fix is a larger board or supply |
| Total demand kVA is high but phase current looks acceptable | Three-phase apparent load may still affect upstream equipment | Transformer, supply, generator, switchboard and submain assumptions | Phase current alone settles upstream capacity |
| Connected kVA is much higher than demand kVA | Demand factors are doing heavy work | Factor source, future use and whether assumptions are preliminary | Low demand kVA proves long-term capacity |
| EV or managed load is included | Controls or load management may affect the row basis | Charger settings, manufacturer data, load-management design and DNSP conditions | The worksheet settles the charger arrangement |
Boundary with load current, EV loads, phase balancing and voltage drop
| Next question | Use this worksheet result as | Check with | Do not assume |
|---|---|---|---|
| What current does one load draw? | A source for a row if already known | Load current calculator | One-load current is the whole board demand |
| What kVA follows from kW and PF? | A row basis before demand factors | kVA, kW and PF calculator | Power relationship values include demand factors |
| What does an EV charger contribute? | One row in the worksheet | EV charger load calculator | Charger acceptance or DNSP acceptance is decided here |
| Which phase should be changed? | Phase demand evidence | Phase balancing calculator or project review | The maximum phase should be moved automatically |
| What voltage drop follows from demand current? | Demand-current input | Submain or voltage-drop calculator | Cable sizing or voltage-drop review is complete |
| Is the supply or switchboard suitable? | A documented worksheet record | Current standards, DNSP, manufacturer and competent review | Positive capacity remaining settles suitability |
Keeping these boundaries clear prevents the page from becoming a vague switchboard decision tool. Maximum demand is one important input to the next decision, not the whole design.
Stop points
- The demand factor source is unknown, guessed, stale or not tied to the project basis.
- The row source is unclear: nameplate, measured value, schedule value, allowance or per-item value.
- The board, tenancy, meter or load-schedule reference is missing.
- The available-capacity value is not tied to a real board, supply, main switch, design threshold or authority basis.
- Single-phase rows have not been allocated to actual or proposed phases.
- Future loads, EV chargers, load management, lifts, motors, cyclic plant or tenant allowances are present but not separately reviewed.
- The result is being used to select cable size, protection, consumer mains, switchgear or supply capacity directly.
- The result will be affected by DNSP/network requirements, local authority requirements, manufacturer data, project documentation or current Australian standards.
- The worksheet current is being treated as a final installation decision rather than a calculation record.
These stop points do not make the worksheet useless. They identify where the entered arithmetic stops being the strongest evidence for the next decision.
Standards and authority context
Australian maximum-demand work must be checked against current standards, project documentation, local authority or DNSP conditions, equipment data and professional judgement. This worksheet does not reproduce AS/NZS demand tables and does not encode a universal maximum-demand method. It lets the user enter the factors being used and records the arithmetic result.
The wording matters. A result can be "the maximum demand current from this entered worksheet" without being "the authorised maximum demand for the installation." The first is an arithmetic statement. The second requires design, authority and verification context outside this page.
Recording the basis
A useful maximum-demand record should state the switchboard or load-schedule reference, supply context, voltage basis, row sources, phase allocation, demand factors, maximum phase current, total demand kVA, available-capacity comparison and reviewer.
Example record: "Workshop DB-1, three-phase worksheet, 400/230 V, maximum phase demand 60.75 A on L2, total demand load recorded from entered rows, demand factors entered from project worksheet, available-capacity comparison 100 A."
That record gives another reviewer a clear starting point. It does not replace the project review, standards assessment, supply authority process, switchboard design or final verification of the installation.
Three-phase workshop schedule
A workshop worksheet includes one balanced three-phase equipment load and one single-phase L2 load, with both demand factors entered by the reviewer.
- Supply
- Three phase
- Rows
- 2
- Available capacity
- 100 A
- Voltage context
- 400/230 V
- L1 demand40.75 A
- L2 demand60.75 A
- L3 demand40.75 A
- Total demand load32.84 kVA
Capacity remaining from the entered comparison value is 39.25 A.
The L2 phase sets the maximum demand current in this entered worksheet. The result should be reviewed with the load schedule source and project requirements.
- 400 V three-phase and 230 V line-to-neutral context.
- Demand factors are entered by the user.
- No fixed maximum-demand rule or final installation decision is embedded.
Single-phase small tenancy worksheet
A small single-phase worksheet combines an entered 32 A circuit and a 6 kW equipment allowance with a user-entered 60% demand factor.
- Supply
- Single phase
- Rows
- 2
- Available capacity
- 80 A
- Voltage context
- 230 V
- L1 demand51.57 A
- L2 demand0 A
- L3 demand0 A
- Total demand load11.86 kVA
Capacity remaining from the entered comparison value is 28.43 A.
The worksheet result is a planning current for the entered assumptions, not a final supply-capacity or switchboard decision.
- 230 V single-phase context.
- Power factor is entered for the kW equipment row.
- Available capacity is an entered comparison value.
EV addition review
A three-phase board review adds a 32 A single-phase EV charger row and a future allowance beside an existing balanced load row.
- Supply
- Three phase
- Rows
- 3
- Available capacity
- 100 A
- Voltage context
- 400/230 V
- L1 demand63.49 A
- L2 demand47.49 A
- L3 demand31.49 A
- Total demand load32.86 kVA
Capacity remaining from the entered comparison value is 36.51 A.
The EV charger is one entered row in the worksheet. Charger selection, load management and DNSP review remain separate tasks.
- The EV charger row is entered at 32 A.
- The existing load demand factor is entered by the reviewer.
- Supply upgrade and DNSP decisions are outside this worksheet.