How to size cable in Australia
A practical guide for moving from load current to a traceable Australian cable-size candidate without replacing current standards or project review.
What cable sizing means here
In this site, cable sizing means checking whether a user-entered metric cable-size candidate is worth carrying forward. It is not a complete selection service. The workflow is useful when a project already has a load, a route, a candidate label and source data for current-carrying capacity or voltage drop.
The useful outcome is a clear record: current basis, candidate label, entered current-carrying-capacity source, voltage-drop data, route length, target and review result. That record can then move into current standards, project documentation, protection and installation review.
Review sequence
- Confirm the load current. Use known current where available, or calculate current from kW or kVA with the correct phase and voltage basis.
- Name the cable run. Keep board, circuit, equipment and drawing references visible.
- Enter the candidate metric cable-size label exactly as it appears in the project record.
- Enter current-carrying capacity from the project source, manufacturer data, reviewed design document or standards source document.
- Enter voltage-drop data that belongs to the same candidate and circuit context.
- Enter route length as the installed one-way path.
- Compare current-carrying capacity margin and voltage-drop margin together.
- Carry forward only with the source documents attached.
Candidate review matrix
| Review area | What to check | Why it changes the answer |
|---|---|---|
| Load basis | Current, kW, kVA, voltage, phase and power factor | A different current changes capacity and voltage-drop margins |
| Candidate label | Metric size, material and cable family | The label alone does not define current-carrying capacity |
| Current-carrying capacity | Source value in A and the basis behind it | Installation and derating assumptions can change the value |
| Voltage-drop data | mV/A/m or R/X values for the candidate | A mismatched data source changes the voltage-drop result |
| Route length | Installed one-way path | Long routes can fail voltage drop even when current margin exists |
| Protection context | Protective device, fault duty and withstand review | A cable can pass load checks and still need protection review |
Reading candidate outcomes
A carry-forward result means both entered comparisons have margin in the worksheet. It does not mean the cable is approved for installation. It means the candidate has enough arithmetic support to continue into project review with the source data attached.
A current-carrying capacity review result points to the current source, capacity source, installation basis or candidate label. A voltage-drop review result points to route length, data source, target, voltage basis or candidate label. If both checks need review, the candidate should not progress until both source chains are corrected.
Records that prevent rework
| Field | Record it as | Avoid |
|---|---|---|
| Candidate size | Metric label plus material where known | Label with no source |
| Current-carrying capacity | Value, source and installation basis | Bare amp value |
| Voltage-drop data | mV/A/m or R/X value and source | Data copied from another cable |
| Route | One-way installed path | Drawing shortcut |
| Target | Project review value and source | Habit-based percentage |
| Reviewer note | Limiting comparison and next check | Unqualified pass wording |
Boundaries
- Do not infer current-carrying capacity from the metric label alone.
- Do not publish or copy controlled cable-selection table values into the worksheet.
- Do not skip derating, grouping, installation method, protection, fault withstand or project documentation.
- Do not rely on a candidate review if source data cannot be traced.
- Do not treat a calculator result as an installation approval.
How to size cable in Australia in Australian work
Show the sequence for checking a user-entered metric cable-size candidate against current, voltage-drop and source-data requirements. The useful record is not just the final number or definition; it is the combination of the entered value, the supply arrangement, the equipment or circuit reference and the decision that still needs project review.
cable size workflow for Australian projects using user-entered current-carrying capacity and metric cable data Keep the wording in Australian English, use metric units, and treat 230/400 V a.c. at 50 Hz as the ordinary low-voltage context unless the project information states a different value.
Checks that belong beside this page
- Regional scopeAustralia; Australian English; project, product, DNSP, local authority and standards source documents can override worksheet assumptions.
- Standards contextAS/NZS 3000 and AS/NZS 3008 context noted for project review; current editions, installation conditions, protection data and source documents remain controlling inputs.
- Review timingReview cadence: Annual or when cable-size calculator fields, table/chart pages, Australian standards context, manufacturer data practice or project documentation practice changes.. Update trigger: Calculator field change, metric cable label table change, standards update, manufacturer data convention change or project feedback.
Practical use sequence
For How to size cable in Australia, begin with the circuit, board, load, cable route, equipment item or measurement record named by this topic. Record the value basis, such as current, voltage, kW, kVA, route length, test value, product rating, tariff value or worksheet field, then note the review boundary so another person can see what this page explained and what still needs a project decision.
The strongest How to size cable in Australia record is specific enough to be reviewed later. It names the Australian context, keeps the entered assumptions visible, separates calculation support from compliance decisions and shows where a calculator, table, chart or term definition should be opened next.
Record detail to capture
Keep the How to size cable in Australia note attached to Australia; Australian English; project, product, DNSP, local authority and standards source documents can override worksheet assumptions.. When the page is used during design, estimating, testing, review or study work, write the entered assumption, the source that supplied it, the circuit or equipment label and the person or role that must review the following action.
For How to size cable in Australia, the review cadence is Annual or when cable-size calculator fields, table/chart pages, Australian standards context, manufacturer data practice or project documentation practice changes. and the update trigger is Calculator field change, metric cable label table change, standards update, manufacturer data convention change or project feedback.. If the topic connects to Cable size, open that page after the current definition, input basis or boundary has been recorded, so the next calculation inherits the right Australian context.
A complete How to size cable in Australia record leaves four facts visible: why the page was opened, which Australian supply or equipment context applies, which value remains user-entered and what later change would alter the result. That makes the page useful as a working note instead of a loose reference copied away from the project evidence.
- InputsWrite down the entered values and their units before comparing results across calculators or reference pages.
- LocationKeep the value tied to the board, circuit, cable run, equipment terminal, supply point or worksheet row it describes.
- Authority checkCompare the record with current Australian requirements, DNSP or local authority conditions and product information.
- Review trailRetain the date, edition context and reason for the calculation so later changes can be traced.
Connected AUWiring pages
Use the related pages for How to size cable in Australia when the topic needs a calculator input, lookup table, formula chart or supporting term before the project record is complete. Open Cable size first when that page owns the next value or definition.
- Cable sizeScreen a user-entered cable-size candidate against current-carrying capacity and voltage drop.
- Load currentConvert kW or kVA into design current before cable review.
- Voltage dropCheck voltage-drop arithmetic for the selected run.
- I2t cable withstandReview thermal withstand after protection data is known.