# Arc Flash Survey



## KevinKM (Oct 8, 2012)

I recently received an Arc Flash Survey with a priority 1 item due to a breaker's fault current being too low. The breaker has an interrupt rating of 65k stamped on the break, however in the survey they rate the fault current down to roughly 25,500 what causes the breakers rating to be much less than its interrupt rating. Thanks in advance. If more specifics from the survey are needed please let me know.


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## Big John (May 23, 2010)

I've never heard of anyone derating an AIC, I don't see the sense behind that.

Might they be trying to say that in order to get a "safe" incident energy that the maximum short-circuit current in the circuit can be no greater than 25.5kA?


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## brian john (Mar 11, 2007)

KevinKM said:


> I recently received an Arc Flash Survey with a priority 1 item due to a breaker's fault current being too low. The breaker has an interrupt rating of 65k stamped on the break, however in the survey they rate the fault current down to roughly 25,500 what causes the breakers rating to be much less than its interrupt rating. Thanks in advance. If more specifics from the survey are needed please let me know.


Is this what you are saying

1. What is the fault current at the CB per the Study?
2. The engineer derated the AIC?
3. Ask him for a justification for this.

Like John I have never heard of this and seems unless he can give a justification, a call to the CB manufacture might be in order. Manufactures frown on unwarranted actions that affect their equipment ratings


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## micromind (Aug 11, 2007)

Is the 65KAIC a series rating? 

If so and the system has been modified, the series rating may no longer apply.


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