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Why prospective fault current matters: IcnIpf is 7 kA and the breakers say 6000. Problem?
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Ipf is the most current that could flow in a fault at that point. Every protective device has a limit to what it can safely interrupt, printed on it: the number in the small rectangle — 6000 means an Icn of 6 kA.
| Rating | What it means |
|---|---|
| Icn | The most fault current it can interrupt safely — though it may not be fit to use afterwards |
| Ics | The most it can interrupt and still work as before. Equal to or lower than Icn |
Guidance Note 3 · 2.6.16 · Icn and Ics of protective devices
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