Replace existing ATS in MCC cubicle with new external ATS

[Designer69]

I need to remove an existing Auto Transfer Switch that is internally mounted in an MCC cubicle and replace it with a new larger externally mounted ATS.

My question is, what is the best way to make the connection of the new external ATS to the same MCC? I was thinking use a smaller bucket in the MCC with a circuit breaker and tie in there. Unless it's better to just use an empty bucket with terminal lugs only and connect there?

I'm not too experienced with this so I'd appreciate your help. Thanks

 

[Jraef]

If you have circuit protection ahead of the MCC now, sized to the MCC bus rating (or less), and the existing ATS was simply tied to the bus, then you can just tie to the bus in the same way, adding lugs if it was a direct bus-to-bus connection. All you are doing is changing the location.

But you say you are installing a LARGER ATS? Does that imply a larger source then? In that case, you may need to change to having a main breaker on the MCC, because if the breaker ahead of the ATS generator side was sized per the old generator, and the new one is bigger, it may not match the MCC rating.

You really didn't provide enough details for much more than this.