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Cable Capacity Selector from Verified Reference Data

Reverse-calculate the reference ampacity needed for a load and protective device after an entered installation correction factor.

Inputs

Project inputs and assumptions

Range: 0–100,000 A

Enter the assessed design current Ib after the applicable load and diversity assessment. Use amperes; do not use a cable table value here.

Range: 0.1–100,000 A

Enter the protective-device rated current In in amperes. The selector uses the larger of Ib and In as the governing current for this arithmetic check.

Range: 0.01–2

Enter the verified product of the applicable ambient, grouping, installation-method and thermal factors. This is a project input, not a generic Australian default or a compliance factor supplied by the tool.

Range: 0.01–100,000 A

Enter the candidate cable reference ampacity in amperes before applying the entered correction factor, taken from current AS/NZS 3008.1.1 or the exact manufacturer data for the installation basis.

Result

Candidate adjusted capacity (A)
41.60
Candidate capacity margin (A)
1.60
Governing current used for the check (A)
40.00
Reference ampacity margin (A)
2.00
Required reference ampacity (A)
50.00
Capacity check
The candidate adjusted capacity meets the governing current. Confirm the exact cable, installation method, voltage drop, fault withstand and applicable requirements separately.

Formula

Calculation logic

Formula definitions and substituted values.

Before relying on the result

  • Find the minimum reference ampacity before consulting a cable table
  • Compare a candidate cable against Ib, In and a combined correction factor
  • Use the required reference ampacity to select a cable from current AS/NZS 3008 or manufacturer data; no licensed table is embedded here.

Related calculators

Use the required reference ampacity to select a cable from current AS/NZS 3008 or manufacturer data; no licensed table is embedded here.