Continuity resistance calculator

Continuity Resistance Boundary

Use this calculator after a continuity measurement has already been recorded and the next task is to correct the row for test-lead resistance. The worksheet does not decide conductor size, protective-device operation, final verification or a universal acceptance value.

The main output is corrected resistance. The margin compares that corrected value with the criterion entered by the user. This is intentionally a record worksheet: the calculator performs the arithmetic, while the project procedure, instrument record, conductor path and competent-person review govern how the row is used.

Inputs To Keep With The Record

Continuity records are weak when the conductor path is not identified. Use a reference that can be matched to a circuit protective conductor, bonding conductor, earthing conductor, switchboard row, asset register or test sheet.

Lead resistance should come from the instrument setup or test procedure, not a guess. If the leads were zeroed on the instrument, record the basis used by the original tester. If a lead value is copied into the worksheet, keep that source with the export.

Worked Australian Examples

A protective conductor row records 0.62 ohm measured resistance and 0.12 ohm test-lead resistance. The corrected resistance is 0.62 - 0.12 = 0.5 ohm. Against an entered 1 ohm criterion, the margin is 0.5 ohm, and the voltage at a 0.2 A test current is 0.1 V.

A review row records 1.4 ohm measured resistance with 0.1 ohm lead resistance. The corrected resistance is 1.3 ohm. Against a 1 ohm entered criterion, the margin is -0.3 ohm. That row should stay visible until the test setup, conductor path and criterion source are reviewed.

A bonding conductor row may use a different current and criterion. The calculator can still perform the arithmetic, but the bonding route and project record must show why those entered values belong together.

Review Workflow

Start from the continuity record. Do not shorten the result into a generic status. A useful row should show what was measured, what was subtracted, what criterion was entered and what still needs review.

1. Identify the conductor path and test sheet row.
2. Copy measured resistance from the instrument record.
3. Enter lead resistance from the same test setup or procedure.
4. Enter the test current and criterion source.
5. Review corrected resistance, margin and voltage at test current.
6. Keep the original instrument record, procedure and reviewer notes with the export.

Boundary With Other Protection Records

Continuity resistance is not the same as insulation resistance, fault-loop impedance, prospective short-circuit current or cable withstand. Use the insulation resistance record calculator when the measurement is in Mohm and the record is about insulation. Use fault-loop impedance when the measured value is a loop path used to estimate fault current. Use I2t cable withstand when fault current and clearing time are being compared with conductor thermal withstand.

Keeping those measurement tasks separate prevents one worksheet from pretending to solve the whole verification job. Each page keeps one measurement model visible and exportable.

Australian Standards Context

Australian continuity records sit within current Wiring Rules, verification requirements, workplace procedures, local authority expectations and manufacturer instructions. AS/NZS 3000 and AS/NZS 3017 are named as context because continuity records belong in that verification environment.

This page does not reproduce controlled tables, test procedures, legal thresholds or conductor-selection rules. The user enters the comparison criterion and keeps the source with the project record. State or territory requirements, workplace rules, manufacturer instructions and competent-person review can override the worksheet basis.