double fusing

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frank melillo

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i have a job that i am coming from a 600amp fused disconnect in a service to
another fused 600 amp disconnect then to a distrubution board.
i belive that you are double fusing that feeder .
what article can i find this in
this for the 2005 code
 
There is nothing in the NEC that would prohibit multiple fused disconnects like you have discribed.

What you would have is a feeder from the first 600 amp disconnect to the second and then another feeder from that disconnect to the distribution panel.

I am not sure what you feel is wrong with this situation.

Chris
 
frank melillo said:
i have a job that i am coming from a 600amp fused disconnect in a service to
another fused 600 amp disconnect then to a distrubution board.
i belive that you are double fusing that feeder .
what article can i find this in
this for the 2005 code
Click to expand...

Are you possibly getting confused with art.240.8 Fuses in Parallel?
 
This is done all the time where multiple disconnects installed in a distribution path are needed. Most safety/disconnect switches have a withstand rating of 5kA without fuses, so a fused switch is needed instead of a non-fused disc when fault currents are >5kA.
 
ron said:
This is done all the time where multiple disconnects installed in a distribution path are needed. Most safety/disconnect switches have a withstand rating of 5kA without fuses, so a fused switch is needed instead of a non-fused disc when fault currents are >5kA.
Click to expand...


The first fused switch should take care of the interrupting current.

The issue with fuses of the same value in series is that in a fault both will likely blow. Double the cost and a major confusion factor if someone didn't know about the second set of fuses.

IMHO

RC
 
could he be thinking of tapping a taped. Hey people, you need to bring more information to the the table in order to get a more reliable answer. Always describe things in some order which helps us to form a drawing in our -mind-
 
RC,
The first set of fuses only takes care of the fault current and the withstand rating for that switch, and may take care of it if the downstream non-fused switch is listed with the specific upstream fuse, but often they are not tested as a combination unless the fuse is actually residing in the switch, making the second switch a fused switch too.
 
ron said:
RC,
The first set of fuses only takes care of the fault current and the withstand rating for that switch, and may take care of it if the downstream non-fused switch is listed with the specific upstream fuse, but often they are not tested as a combination unless the fuse is actually residing in the switch, making the second switch a fused switch too.
Click to expand...
Almost all non fusible disconnects I have seen, allow the fuse to be located anywhere 'upstream' of the switch.
 
Almost all non fusible disconnects I have seen, allow the fuse to be located anywhere 'upstream' of the switch.
Click to expand...
Although that is what logic dictates, I guess I've been seeing different switches that you have. I'll continue to check the inside cover of switches to find the ones you've been seeing.
 
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