Reuse existing MCC bucket to feed panel

[bcm]

Happy Thursday, my sparky friends!

I have been asked to reuse a spare bucket in a 600A, 480V, 3 ph MCC to feed a 200A, 120/240V, 1 ph panelboard. I've never seen an MCC used for anything but serving motors in the past, but I haven't found anything in the NEC that prohibits serving a panelboard. It feels like a gray area code-wise.

As far as the design, the MCC is 600A, 480V 3 ph fed by 2 sets of (3) 350 MCM & 1#2 ground. The bucket is a spare from a removed 15 HP AC motor. Can I replace the "guts" (HOA, transformer, etc.) from the bucket with a 100A, 480V fuse or CB? I would then put a step-down transformer downstream which would bring voltage to 120/240 for the loadcenter, and wouldn't it also provide the required neutral?

Thanks so much for your input!

 

[tom baker]

You might be better off to purchase a new bucket. That would maintain UL listing and have MCC drawings updated

 

[jim dungar]

It is not a gray area. It is not prohibited and is actually very common.

The issue is with primarily the overcurrent protection being rated for branch circuits. If you have fuses you are good to go. If you have a circuit breaker it will probably need to be replaced.

 

[David Castor]

It's commonly done. No NEC issues as long as you have the proper overcurrent device. Just keep in mind that the Motor Circuit Protectors (MCP) commonly used in combination motor starters cannot be used to protect a feeder. MCPs do not have any overload (thermal) element, just a magnetic trip. You have to install a standard thermal-magnetic MCCB.

 

[petersonra]

Its a common practice to feed all kinds of external branch circuits from an MCC bucket.

In fact, most MCC manufacturers have standard options for feeder breakers or fused disconnects and most also have a standard option for panelboard and transformer.

If the bucket is adequately sized for the transformer I would not be at all concerned about using it. Just take out what you don't need.

Another poster mentioned being aware that there is some chance that a motor circuit protector was used instead of a MCCB. If so, you should be able to get a MCCB of the same frame size to replace the MCP that would use the same handle.