200A RK1 fuse upstreams of 250A circuit breaker

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faresos

Senior Member
Hello everyone...

We have a situation where we have to change the fuse size from 250A fuse to 200A RK1 fuse (to use 200A switch in lieu of 400A). This fuse feed a panel located in different room that has 250A circuit breaker. Is there any code violation by having 200A fuse upstream of 250A breaker?The total load on this panel approx. 70KVA (approx. 85A @ 480V).

Thanks,
 
No, there is no code that prohibits installing a smaller OCPD upstream from a MB panelboard provided that the upstream OCPD is sized for the load. The breaker in the panelboard now will act as just a disconnecting means.

Chris
 
There is no code violation, as the downstream circuits are protected at or below their ratings. From a functional standpoint, I would add a sign at the 250A breaker to indicate it is protected at 200A upstream for troubleshooting.

The new 200A fuse now essentially be comes the main OCPD.
 
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