I2t
I2t meaning in Australian cable withstand and protection energy records.
I2t in energy-let-through records
I2t is a fault-current-over-time value used in cable withstand and protective-device energy records. It is commonly read as current squared multiplied by time, with the surrounding record showing the fault current, clearing time and source data.
In Australian cable and protection worksheets the term appears beside metric conductor records, protective-device let-through data and short-circuit withstand discussions. Use it as a record term, not as a final cable or device selection.
Inputs behind the value
An I2t value is only meaningful when the fault event and data source are visible. The same label may appear in a cable withstand worksheet or in product data for a fuse or other protective device.
| Record context | Keep visible | Why it matters |
|---|---|---|
| Fault event | fault current and clearing time | Shows the event used to form the value |
| Conductor withstand | conductor material, area and source basis | Keeps cable data separate from device data |
| Device let-through | product reference and manufacturer source | Separates entered product data from calculated withstand |
Cable withstand vs device let-through
Cable withstand and device let-through are related but not identical records. A cable worksheet may calculate whether entered conductor data has enough withstand margin, while a fuse or device row may supply energy information from product data.
The glossary term does not publish conductor constants, reproduce controlled tables or decide suitability. Current project, product and licensed data remain the sources for the actual review.
Using I2t with cable withstand
Use the I2t cable withstand calculator when fault current, clearing time and conductor data are available. Keep the energy value beside the source record so later cable, fuse or protection review can see which assumptions produced it.
Source and review
Check the terminology source, review timing and Australian application before carrying this term into a project record.
| Item | Value |
|---|---|
| Source | AUWiring I2t cable withstand calculator wording and cable protection guide content. |
| Source type | Australian terminology |
| Derivation basis | AUWiring Australian glossary term; no controlled standards tables are reproduced. |
| Last checked | 2026-07-13 |
| Review interval | Annual terminology review or sooner if I2t calculator wording changes. |
| Review trigger | Update when I2t calculator inputs, cable withstand guide or protection terms change. |
| Version used | T26-2026-07-13 |
| Australian application | Australia; Australian English protection terminology. |