Current Limiting Protective Devices and its effects on Fault Calculations

Question: Currently I have a protective device that is rated for 35K, but my bus fault is at 61k . The upstream device is a current limiting fuse and has a let-thru current of 13K. My question is we can modify or adjust the Fuse to show the let-thru fault of 13K in order to bring down the fault at the downstream bus?

Answer: For the purposes of fault calculations, any and all protective devices are ignored to find the maximum available fault current.

See attached for an excerpt from the IEEE 242 Buff Book regarding this.

Per IEEE Buff Book Std.242-1986 Paragraph 2.3.6, “Short-Circuit calculations should be made without considering the effects of current-limiting devices to determine the prospective short circuit current”.
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