230.95 paragraph about fuses

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While not as common as it used to be, bolted pressure fusible switches were often used in the larger sizes in services. This is to ensure that the components are rated adequately for the available fault current in the event of a line to line fault where the GFP system would not be in play.
 
But that paragraph seems to link the rating of the fuse to the rating of the switch, rather than both depending upon the availability fault current.

??

Jon
 
This is my vision of situation in example.
At the point of installation we have 100kA available S.C.
800A rated switch with a trip relay controlled by ground fault controller opens the switch at current between 1,100A - 10,000A.
At 10kA and above ground fault, the controller will allow fuses to open the fault.
 
Ahh, so the trip relay operates in a limited range and does not attempt to open the switch if the fault current exceeds a certain amount, and the fuse has to be capable of opening anything above that.

Thanks for clarifying.

-Jon
 
victor.cherkashi said:
This is my vision of situation in example.
At the point of installation we have 100kA available S.C.
800A rated switch with a trip relay controlled by ground fault controller opens the switch at current between 1,100A - 10,000A.
At 10kA and above ground fault, the controller will allow fuses to open the fault.
Click to expand...
Yep. Once, a vendor installed a motor controller (contactor switch) and routed the GF relay contacts to open the switch (contactor) if a ground occurs! The contactor switch contacts got damaged due excessive ground fault current experienced after a motor ground fault! The solution to the problem was routing the GF contact trip to the shunt trip contact of the supply breaker! The breaker has a higher interrupting rating than the contactor switch!
 
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