OCPD Question

[industrial1003]

I have a unique piece of metal forming equipment that has it's own supply conductor OCPD in the form of a fused disconnect switch for the machine. The machine was built for later expansion if needed so the disconnect switch is oversized and using UL listed fuse reducers (100A switch with 50A fuses). Can I wire this to a 100A breaker in my panelboard as long as the conductors supplying the machine are rated for the 100A breaker after the required derating? It would save time if the machine is expanded down the road. Also, am I correct in assuming the breaker in question is considered a feeder OCPD since the fuses at the machine disconnect would be considered the branch OCPD?

We run into a lot of this in our facility as we use modular equipment, and most is overbuilt. Any help would be appreciated.

 

[Dennis Alwon]

As long as the machine is properly protected by the disconnect at the machine and your wire sizes are appropriate I see no issue with it. It would be like feeding a sub panel with 100 amps then take off a 50 amp breaker to a machine. Not an issue, IMO

 

[industrial1003]

Dennis,

Thanks for the reply. It was the direction we were leaning, but just wanted to get someone elses opinion. Not many people oversize things for future expansion in todays world of cost recovery, but we found out that it becomes much more costly to redo it later than oversize it from the begining. Thanks again.

 

[Dennis Alwon]

Dennis,

Thanks for the reply. It was the direction we were leaning, but just wanted to get someone elses opinion. Not many people oversize things for future expansion in todays world of cost recovery, but we found out that it becomes much more costly to redo it later than oversize it from the begining. Thanks again.

No doubt about that. We almost always size wires a bit larger if there is a chance for larger loads. Generally, for me, it would be to a sub panel or a service.