I2t cable withstand workflow
How to prepare fault current, clearing time and conductor assumptions before using an Australian I2t cable withstand worksheet.
Withstand record purpose
I2t review connects fault current, clearing time and conductor assumptions. The public calculator can compare entered fault duty with entered withstand assumptions, but it cannot know the full protective-device behaviour or final conductor requirements.
Keep the source of each input with the worksheet result.
Workflow
- Prepare fault current from source or loop data.
- Record the clearing time source.
- Record conductor material, role and cross-sectional area.
- Enter the k value or selected assumption only when it has a source.
- Compare fault duty with withstand and write the review note.
I2t record table
| Field | Record | Review point |
|---|---|---|
| Fault current | Source calculation, loop result or study value | Must match the location reviewed |
| Clearing time | Device data or project source | Device behaviour controls duty |
| Conductor role | Active, neutral, protective conductor or other role | Assumptions differ by role |
| Material and size | Entered conductor data | Must match the cable candidate |
| Withstand basis | k value or entered withstand | Needs traceable source |
| Review note | Margin and unresolved checks | Avoids final approval wording |
Reading the result
If calculated duty exceeds entered withstand, check fault current, clearing time, conductor assumptions and device data before changing conductor size. If the result has margin, still carry the input sources forward.
The result belongs beside cable sizing and protection records, not as a standalone approval.
Boundaries
- Do not use I2t as a complete cable-selection method.
- Do not invent k values without source context.
- Do not separate clearing time from device data.
- Do not describe the comparison as final compliance.