Protective conductor check calculator
Compare an Australian protective conductor candidate area with a required area entered from a project or standards basis.
Scandidate_total = Scandidate x Nparallel; Smargin = Scandidate_total - Srequired; utilisation_percent = Srequired / Scandidate_total x 100- Candidate area and required area are entered by the user.
- Parallel conductor count multiplies the entered candidate area only when the project record supports that treatment.
- The calculator does not calculate the required area from standards tables.
- Keep the required-area source with the exported record.
| Variable | Meaning | Unit | Use |
|---|---|---|---|
| Scandidate | Candidate conductor area | mm2 | Area of one entered protective conductor or earthing conductor. |
| Nparallel | Parallel conductor count | count | Number of entered parallel conductors included in the comparison. |
| Scandidate_total | Total candidate area | mm2 | Candidate area multiplied by the entered parallel conductor count. |
| Srequired | Entered required area | mm2 | Required conductor area supplied by the user from the project, standard, manufacturer or reviewer basis. |
| Smargin | Area margin | mm2 | Total candidate area minus entered required area. |
| utilisation_percent | Requirement utilisation | % | Entered required area divided by total candidate area times 100. |
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Protective conductor check calculator technical guide
Compare an entered protective conductor area with a required area supplied from an Australian project or standards basis.
Field use cases
Use this page when the required protective conductor area is already known from a project source and the next task is to compare an entered candidate. The calculator is useful for checking a conductor schedule, reviewing an as-built row, comparing a maintenance finding or preparing a handover record where another person must see the candidate area and required-area source together.
The page is deliberately not a conductor selector. It does not reproduce controlled sizing tables and it does not decide whether the required-area value is correct. It keeps the comparison transparent so a reviewer can question the conductor path, source basis and project assumptions.
| Work setting | Useful input | Output to record |
|---|---|---|
| Switchboard schedule check | Candidate area and required area from a schedule. | Area margin and source basis. |
| Earthing conductor review | Entered conductor area and reviewer basis. | Total entered area and comparison state. |
| Parallel conductor note | Area of one conductor and count included in the record. | Equivalent entered area and margin. |
| Maintenance finding | Existing conductor area and required-area source. | Shortfall or spare area for review. |
Input basis
The strongest record starts with a clear conductor reference. Use a circuit, protective conductor, earthing conductor, bonding conductor, switchboard row or drawing reference that another reviewer can trace. A bare area value is weak because it does not show where the conductor belongs.
Candidate area is entered in mm2. The required area is also entered in mm2. If the required area came from an adiabatic calculation, a current standard, a project schedule, manufacturer data or a competent-person instruction, keep that source with the worksheet. The calculator only compares the values.
| Input | Calculator treatment | Outside the calculator |
|---|---|---|
| Candidate area | Used as the entered conductor area. | Whether the conductor material, route and installation match the record. |
| Parallel conductors | Multiplies the entered candidate area. | Whether parallel treatment is valid for the project. |
| Required area | Used as the comparison basis. | How that required area was produced or authorised. |
| Source basis | Displayed in the result record. | Current standards, manufacturer data and project documentation. |
Review workflow
- Identify the conductor path and record reference.
- Enter the candidate conductor area in mm2.
- Enter the parallel conductor count only when the project record supports that comparison.
- Enter the required area from the source basis.
- Name the source basis in plain project language.
- Review margin and utilisation.
- Keep the required-area source, conductor arrangement and reviewer note with the export.
The workflow should start from evidence, not from the desired margin. If the result is below the entered requirement, do not change the source basis until the record looks better. Review the conductor path and the source that produced the required area.
Worked Australian examples
A distribution board record compares a 16 mm2 protective conductor with a 10 mm2 required area. With one conductor entered, the total candidate area is 16 mm2, the margin is 6 mm2, and utilisation is 62.5%.
A parallel row compares two 6 mm2 conductors with a 10 mm2 entered requirement. The total candidate area is 12 mm2, and the margin is 2 mm2. That row is meaningful only if the project basis allows the parallel conductor treatment.
A maintenance review compares a 6 mm2 conductor with a 10 mm2 entered requirement. The margin is -4 mm2. The result should remain visible until the conductor record, required-area source and project assumptions are reviewed.
Boundary with I2t and loop impedance
Use the I2t cable withstand calculator when the missing question is thermal withstand from fault current, clearing time and k value. Use the fault loop impedance calculator when the starting value is a measured or calculated loop impedance. This protective conductor page starts later in the workflow: it assumes the required area has already been sourced and only compares it with an entered candidate.
| Task | Use this page? | Better route when not this page |
|---|---|---|
| Compare entered candidate area with entered required area. | Yes. | Not applicable. |
| Calculate adiabatic withstand from current and time. | No. | I2t cable withstand calculator. |
| Estimate current from loop impedance. | No. | Fault loop impedance calculator. |
| Choose final conductor size from all rules. | No. | Project design and current standards review. |
Australian standards boundary
Australian protective conductor and earthing conductor decisions sit inside current wiring rules, cable selection context, local authority requirements, product data and project documentation. This page names AS/NZS 3000 and AS/NZS 3008.1.1 as context, but it does not reproduce controlled tables or final sizing rules.
The required area remains an entered value. That conservative boundary protects the page from implying that one public worksheet can replace project review. State or territory requirements, DNSP conditions, manufacturer data and competent-person judgement can override the worksheet basis.
Stop points
- The conductor reference cannot be traced to a circuit, switchboard or drawing.
- The required-area source is missing or copied without context.
- Parallel conductor treatment is assumed rather than recorded.
- The candidate area is below the entered required area.
- The comparison is being used as a complete conductor-selection decision.
Protective conductor record
A distribution board record compares a 16 mm2 protective conductor with a 10 mm2 required area copied from the project basis.
- Conductor reference
- CPC-DB1
- Candidate area
- 16 mm2
- Parallel conductors
- 1
- Required area
- 10 mm2
- Source basis
- Project conductor schedule
- Total candidate area16 mm2
- Area margin+6 mm2
- Requirement utilisation62.5%
Entered area is at or above the entered basis.
The entered area is above the entered required area, but the source basis and conductor arrangement still need to travel with the record.
- Candidate and required areas are entered by the user.
- The worksheet does not select conductor size.
- Parallel treatment must match the project record.
Parallel conductor comparison
A reviewer compares two entered 6 mm2 protective conductors with a 10 mm2 required-area basis for the same path.
- Conductor reference
- CPC-PARALLEL
- Candidate area
- 6 mm2
- Parallel conductors
- 2
- Required area
- 10 mm2
- Source basis
- Reviewer entered requirement
- Total candidate area12 mm2
- Area margin+2 mm2
- Requirement utilisation83.3%
Entered area is at or above the entered basis.
The total entered candidate area is above the entered basis, provided the parallel conductor assumption is valid for the installation.
- Parallel conductors are entered as a count.
- No current-sharing or installation table is embedded.
- The required area remains source-controlled outside the calculator.
Below entered requirement
A maintenance note compares a 6 mm2 conductor with a 10 mm2 required-area basis and needs the shortfall made visible.
- Conductor reference
- CPC-REVIEW
- Candidate area
- 6 mm2
- Parallel conductors
- 1
- Required area
- 10 mm2
- Source basis
- Manual reviewer basis
- Total candidate area6 mm2
- Area margin-4 mm2
- Requirement utilisation166.7%
Entered area is below the entered basis.
The entered candidate is below the entered basis, so the conductor record and required-area source need review before the row is used.
- The required area is entered by the user.
- The comparison is arithmetic only.
- The conductor path and source basis remain external evidence.