MCP in MCC Bucket without OL

[corvalan]

I want to know the community's opinion on the following:

Situation:

An MCC bucket has only an MCP (not a circuit breaker). This bucket has not been modified in the field. It came as such.

The MCC bucket is listed as a feeder bucket by UL, not a controller bucket

Wire from the MCC bucket terminated at a downstream VFD with internal OL protection, properly configured.

Questions:

A. Does this installation meet the NEC regarding the following:

A.1: Is this cable between the MCP and the VFD a motor branch circuit or a feeder circuit?
A2.: Is it regulated by Article 430 or 240?
A.3: The cable between the MCP and VFD is not protected for an OL condition, like a high-resistance ground fault current. Is this compoliante still?
A.4: Does the NEC require the installation of an additional OL protection at the bucket for the OL protection of this cable (not the motor)?

B: Does this installation meet the UL requirements for the MCC and feeder bucket in the following:

B.1: The bucket is UL-listed as a feeder. Does this listing allow the feeder bucket to house an MCP instead of a circuit breaker?

C: Do not address the following because it is irrelevant.
C:1. If this bucket is listed as a controller bucket, this installation is obviously a violation of the listing. This is clear.
C2: Assume that the MCP satisfies the requirement of the maximum OCPD size. So there is no code violation there.
C.3: Assume that the cable between the MCP and VFD has proper short-circuit and ground-fault protection by the MCP. No violation there.

If you can, please keep your comments relevant to the situation of the two following situations:
1. OL cable protection between the MCP and VFD
2. UL requirements to install an MCP in a UL-listed feeder bucket.

Thanks so much

 

[D. Castor]

Lots of questions, but my simplistic understanding is that there is no code-compliant way to connect any load to this bucket without replacing the MCP with a circuit breaker or fuse. I frequently come across this situation when doing field data collection.

The fact that is was shipped this way doesn't change anything, imo. Mistakes are made everywhere.

 

[don_resqcapt19]

I agree...there is no code compliant way to use that device to supply a feeder or a branch circuit.
It appears the listing mark is in error and you need to take that up with the manufacturer.

 

[jim dungar]

How old is this installation? Things have changed over the years.
I remember some OCPD buckets being separate from the motor controller bucket. These were intended to be mounted above each other with interlocked doors.