What distinction does the manufacturer make?
Schneider Electric's cited switch-disconnector guidance describes Icw as an RMS current with a stated duration, and Icm as a peak making-current quantity. It also distinguishes a device-alone value from a value conditional on upstream protection. Those descriptions concern the named product context, not an interchangeable rating system for all equipment.
Critical Power Drafting is independent and is not affiliated with Schneider Electric. Preserve the actual manufacturer terminology and engineering study basis, especially when documents use different standards or rating conventions.
Sources: Schneider Electric: Compact NSX switch-disconnector Icm and Icw definitions
Which fields stop an incomplete comparison?
A schedule cell reading only 25 kA leaves important questions unanswered. Trace the approved equipment tag and data-sheet revision to the exact row and footnote. Keep a study result separate from an equipment rating so the engineer can compare the appropriate quantities.
| Field | Record | Review |
|---|---|---|
| Quantity | Peak or RMS and manufacturer symbol | Do not compare bare numbers |
| Function | Making, withstand or interruption | Retain the actual rating category |
| Duration | Time attached to a withstand value | Do not omit it from the note |
| Conditions | Voltage and stated equipment arrangement | Use the approved case |
| Protection basis | Device alone or specified combination | Retain the limiting-device reference |
| Review | Study revision and engineering disposition | Do not infer suitability from a unit match |
Why do matching kA numbers not establish equivalence?
Illustrative example. Fictional source A states 25 kA RMS for one second. Fictional source B states 25 kA peak making current. The two labels have the same numeral and current unit but describe different quantities and functions. Mark the comparison unresolved instead of copying a matched rating into the schedule.
No universal conversion factor is applied here. Fault waveforms, asymmetry, rating definitions and approved protection arrangements matter. These numbers are synthetic, are not ratings of the cited product and do not establish an equipment pass or fail.
What should remain with the issued annotation?
Retain the actual source table, its applicable footnotes, the study reference and the engineer's approved wording. If a value depends on an upstream device, check that the identified combination is the one represented on the approved one-line. A higher isolated number is not evidence that a different assembly is suitable.
The drawing review records approved engineering inputs. It does not perform a fault study, select protection, certify coordination or authorize work. Engineering sign-off is performed only by the registered engineer on the job.
Common questions
What else should the bid team know?
Does kA alone identify the rating?
No. Record the quantity, function and applicable duration or conditions.
Can a making rating replace an interrupting rating?
No. Preserve the distinct rating categories for engineering review.
Should every peak value be divided by the same factor?
No. Use the actual approved rating and study definitions.
Primary sources
- Compact NSX switch-disconnector Icm and Icw definitionsSchneider Electric