Continuity, loop resistance, insulation resistance, screen / sheath and test voltage for each cable section, checked and recorded in one place.
After a cable is laid, each section is tested before it is energised. This tool takes your readings, compares the loop resistance with what the conductor and length should give at the test temperature, corrects insulation resistance to 20 °C, checks every result against your acceptance limits and issues a PDF record with sign-off boxes.
Measured on the cable or the soil beside it, not the air temperature.
Set this from the project specification or owner requirement. It is not a universal figure.
Correcting a warm reading to 20 °C raises it, so as measured is the stricter choice above 20 °C. Below 20 °C the corrected reading is lower and therefore stricter.
10-minute ÷ 1-minute reading. A value under 1 means the reading fell during the test. It is of limited use when the 1-minute reading is very high.
Loop length is the total conductor length in the measured loop, so a loop that goes out and back counts both ways. Leave a reading blank if it has not been taken; the section shows as incomplete. IR is conductor to earth, in MΩ.
| Section | Loop length (m) | Continuity | Loop R (Ω) | IR 1 min (MΩ) | IR 10 min (MΩ) | Screen cont. | Screen IR (MΩ) |
|---|
| Section | Length (m) | Cont. | Loop R meas. (Ω) | Loop R exp. (Ω) | Dev. (%) | IR 1 min (MΩ) | IR at 20 °C (MΩ) | IR × km at 20 °C (MΩ·km) | PI | Screen cont. / IR | Result |
|---|
PASS* means every limit is met but there is a note to review, such as a low polarisation index or a test voltage above the cable rating.
Every step is shown so a reading can be checked by hand.
Each conductor, and the screen or sheath where fitted, must show a continuous path end to end. A fail on any one fails the section.
The expected value comes from the conductor resistance, the loop length and the test temperature. The measured value is compared with it as a percentage.
A high reading points to a poor joint or termination, or a longer route than entered. The tool also shows the length implied by the measured value.
Insulation resistance falls as the cable warms. As a rule of thumb it halves for each 10 °C rise, so the reading is corrected to 20 °C. Multiplying by length gives a figure in MΩ·km that does not depend on how long the section is. The length is the conductor length entered, so both legs of an out-and-back loop count, which allows comparison with a manufacturer MΩ·km figure for the same cable.
If a 10-minute reading is recorded, the index is the 10-minute reading divided by the 1-minute reading. A value below the flag limit does not fail the section but is noted for review. The index is of limited meaning when the 1-minute reading is already very high (IEEE 43, a rotating-machine standard used here only as guidance, treats readings above about 5,000 MΩ this way), so do not over-read a low index on a clean, dry cable.
| Item | Value |
|---|---|
| 6 mm² Cu, 3.08 Ω/km, loop 1,200 m, 30 °C | factor 1.0393 |
| Expected loop resistance | 3.841 Ω |
| Measured 3.86 Ω, deviation | +0.49 % |
| IR at 1,000 V, 1 min, as measured | 2,500 MΩ |
| IR corrected to 20 °C | 5,000 MΩ |
| IR × length | 6,000 MΩ·km |
| PI = 3,100 ÷ 2,500 | 1.24 |
| Result against ±5 % and 100 MΩ | PASS |
A section fails if any check fails. It is incomplete if a required reading is missing or invalid, and passes with notes if only a review note is raised. The record fails if any section fails, is incomplete if any section is, and otherwise passes.
It does not hold a standard's limits: minimum insulation resistance, test voltage and tolerance are yours to set from the specification. It uses copper conductors and a rule-of-thumb insulation correction, whereas some specifications or manufacturers give their own factor. It does not cover high-voltage withstand tests, cable fault location or trend analysis across repeat tests.
Quick answers on checking and recording continuity, loop resistance and insulation resistance for each cable section.
After a cable is laid, each section is tested before it is energised. This tool takes your readings for continuity, loop resistance, insulation resistance, screen or sheath and test voltage. It compares the loop resistance with what the conductor and length should give at the test temperature, corrects insulation resistance to 20 degrees C, checks every result against your acceptance limits, and issues a PDF record with sign-off boxes.
The expected resistance is the conductor resistance at 20 degrees C times the loop length divided by 1,000, times 1 plus 0.00393 times the temperature minus 20. The deviation is the measured minus the expected, divided by the expected, times 100, and it is compared with your tolerance. A high reading points to a poor joint or termination, or a longer route than entered, and the tool also shows the length implied by the measured value.
Insulation resistance falls as the cable warms, and as a rule of thumb it halves for each 10 degrees C rise. The corrected value is the reading times 2 to the power of (temperature minus 20) divided by 10. Multiplying by length in km gives a figure in megohm-km that does not depend on how long the section is.
It is the 10-minute reading divided by the 1-minute reading. A value below the flag limit does not fail the section but is noted for review. A value under 1 means the reading fell during the test. It is of limited meaning when the 1-minute reading is already very high, and IEEE 43, a rotating-machine standard used here only as guidance, treats readings above about 5,000 megohms this way, so do not over-read a low index on a clean, dry cable.
Loop length is the total conductor length in the measured loop, so a loop that goes out and back counts both ways. Insulation resistance is conductor to earth, in megohms. Leave a reading blank if it has not been taken, and the section shows as incomplete. The minimum insulation resistance, test voltage and tolerance are yours to set from the project specification. You can apply the minimum to the reading as measured or corrected to 20 degrees C. Above 20 degrees C the as-measured choice is stricter.
A section fails if any check fails. It is incomplete if a required reading is missing or invalid, and it passes with notes, shown as PASS*, if only a review note is raised, such as a low polarisation index or a test voltage above the cable rating. The record fails if any section fails, is incomplete if any section is, and otherwise passes.
Section S1 is 6 mm squared copper at 3.08 ohms per km, with a loop of 1,200 m at 30 degrees C, so the temperature factor is 1.0393 and the expected loop resistance is 3.841 ohms. The measured 3.86 ohms is a deviation of plus 0.49 percent. An insulation reading of 2,500 megohms at 1,000 V corrects to 5,000 megohms at 20 degrees C, which is 6,000 megohm-km, and the polarisation index is 1.24. Against plus or minus 5 percent and 100 megohms, the section passes.
No. It is a working test record and not an approved test certificate. The tool applies the limits you enter and does not know your specification, so confirm limits, test voltages and the test method against the project specification and the cable manufacturer before accepting a cable. It uses copper conductors and a rule-of-thumb insulation correction, whereas some specifications give their own factor. It does not cover high-voltage withstand tests, cable fault location or trend analysis across repeat tests.
Please read before relying on any content on this page or on any result or record produced by it.