Single-phase load distribution calculator
Summarise Australian single-phase circuit records across L1, L2 and L3 for load distribution review.
PhaseTotal = sum(Icircuit by phase); Spread = max(PhaseTotal) - min(PhaseTotal); SpreadMargin = TargetSpread - Spread; MovePrompt = movable circuit on highest phase tested against lowest phase- Circuit currents are user-entered.
- Movable markers are planning notes.
- Move prompts are not circuit instructions.
- Neutral-current and detailed phase-balancing checks remain separate.
| Variable | Meaning | Unit | Use |
|---|---|---|---|
| Icircuit | Circuit current | A | Entered single-phase circuit current. |
| PhaseTotal | Phase total | A | Sum of circuit currents on L1, L2 or L3. |
| Spread | Phase spread | A | Highest phase total minus lowest phase total. |
| TargetSpread | Target spread | A | Entered spread comparison value. |
| SpreadMargin | Spread margin | A | Target spread minus actual spread. |
| MovePrompt | Movable circuit prompt | A | Trial move from highest phase to lowest phase for review. |
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Single-phase load distribution calculator technical guide
Summarise entered single-phase circuit currents across L1, L2 and L3 for Australian load distribution review.
Use this calculator when a board schedule lists individual single-phase circuits and you need to see how they sit across L1, L2 and L3. The output shows phase totals, spread and movable-circuit prompts while keeping circuit work outside the calculator.
Field Use Cases
| Work setting | Real question | Useful action from this page |
|---|---|---|
| Board schedule | Which phase has the highest entered single-phase load? | Sum circuit currents by phase. |
| Load distribution review | Is the spread above the entered target? | Compare highest and lowest phase totals. |
| Circuit record cleanup | Which circuits should stay fixed in the worksheet? | Mark rows as fixed or movable. |
| Phase handoff | Which circuit prompts should be discussed first? | Read move candidates sorted by trial spread. |
| Neutral-current preparation | Do phase current totals need a neutral-current estimate? | Carry totals into the neutral-current calculator. |
The page is most useful before a formal load-sharing discussion because it shows the entered circuit-level source record. It does not tell anyone to move circuits.
Data checklist
| Value | Where it normally comes from | Stop if |
|---|---|---|
| Circuit reference | Board schedule, drawing tag or circuit list | The row cannot be traced. |
| Circuit current | Schedule value, equipment data or measured record | Current values use mixed bases. |
| Phase label | Board schedule or measured record | Phase labels are missing or uncertain. |
| Movable marker | Project planning note | The marker is being treated as a work instruction. |
| Target spread | User-entered review value | The target has no project context. |
If the phase labels are uncertain, use the output only as a list-cleaning prompt. A distribution worksheet is only as useful as the circuit records behind it.
Review Workflow
| Step | Record to check | Move to |
|---|---|---|
| Confirm circuit list | Board schedule or load list | Enter circuit references. |
| Enter circuit current | Schedule current or measured record | Sum phase totals. |
| Confirm phase labels | L1, L2 or L3 record | Read phase spread. |
| Mark movable rows | Project planning note | Read move prompts if spread is above target. |
| Choose next check | Phase balancing, load sharing or neutral current | Use the linked calculator that owns that question. |
The move prompt only tests arithmetic: what the phase spread would be if a movable row from the highest phase were compared against the lowest phase. It does not account for wiring route, protection, isolation, cable entries, switchboard layout or project constraints.
Worked distribution record
A schedule enters four single-phase circuit rows: Circuit A at 30 A on L1, Circuit B at 26 A on L1, Circuit C at 18 A on L2 and Circuit D at 12 A on L3. The target spread is 20 A. The 18 A L2 row is fixed; the others are marked movable.
The phase totals are L1 56 A, L2 18 A and L3 12 A. The spread is 44 A, which is above the entered target. The first move prompt is the 26 A L1 circuit compared against L3, because that trial gives a 20 A spread.
| Value | Result |
|---|---|
| L1 total | 56 A |
| L2 total | 18 A |
| L3 total | 12 A |
| Phase spread | 44 A |
| Target spread | 20 A |
| First move prompt | Circuit B from L1 to L3 |
| Trial spread | 20 A |
The result gives a discussion record for the next check. Any actual circuit work must stay with project documentation and competent review.
Method boundary
| Method element | What this page does | What remains outside |
|---|---|---|
| Phase total | Adds entered circuit currents by phase. | Confirming phase labels and circuit records. |
| Spread | Compares highest and lowest phase totals. | Deciding whether the board arrangement should change. |
| Move prompt | Tests movable circuits on the highest phase against the lowest phase. | Circuit movement, isolation, protection and switchboard work. |
| Status | Compares spread with the entered target. | Project suitability and standards review. |
This calculator is intentionally a worksheet. It exposes the arithmetic behind a distribution question without replacing the professional review around the circuit records.
Stop points
- Circuit references do not match the board schedule.
- Current values use different bases or measurement periods.
- Phase labels are unknown or copied from an older record.
- Movable markers are being read as work instructions.
- The output is being used without checking protection, routing or switchboard layout.
- The real task is aggregate phase balancing or neutral current.
When a stop point appears, keep the output as a distribution note and resolve the source record before taking it into a detailed phase or board review.
Single-phase circuit distribution
A board schedule has two larger single-phase circuits on L1 and needs a spread worksheet before any load-sharing discussion.
- Schedule reference
- SPLD-1
- Circuits
- 4
- Target spread
- 20 A
- Spread44 A
- Highest phaseL1
- Move promptCircuit B
Use the status as a phase-distribution prompt before load-sharing review.
The entered spread is above the target and the first move prompt identifies the movable L1 circuit that gives the lowest trial spread.
- Circuit currents are user-entered.
- Movable markers are planning notes.
- Circuit movement remains outside the worksheet.
Balanced circuit list
A small list has similar phase totals and does not need a move prompt.
- Schedule reference
- SPLD-BALANCED
- Circuits
- 3
- Target spread
- 15 A
- Spread4 A
- Highest phaseL1
- Move promptNone
Use the status as a phase-distribution prompt before load-sharing review.
The phase spread remains below the entered target, so the worksheet can be kept as a distribution record.
- All rows are single-phase current records.
- Target spread is user-entered.
- Neutral current can be checked separately if needed.
Workshop single-phase record
A workshop board has several single-phase rows and one fixed circuit that should not be moved in the worksheet.
- Schedule reference
- SPLD-WORKSHOP
- Circuits
- 4
- Target spread
- 18 A
- Spread32 A
- Highest phaseL2
- Move promptTool B
Use the status as a phase-distribution prompt before load-sharing review.
The move prompt stays limited to movable rows on the highest phase so fixed circuit notes remain visible.
- Fixed circuit notes come from the project record.
- Phase labels are user-entered.
- Load sharing remains a separate task.