2500A Breaker inside MCC or Switchgear

[Electriman]

Greetings,

I have a question. I am working on a MCC that has a 2500 A main breaker. I was wondering if that 2500A section would it be placed in a MCC or switchgear. The size of the section that has a 2500A breaker is 36" x 36" and I don't know whether this is classified as a MCC or switchgear. System voltage is 480 V.

 

[ron]

It could be built to UL 845 (MCC), UL 891 (Switchboard) or 1558 (Switchgear), depends on what you bought or specified.

 

[Electriman]

It could be built to UL 845 (MCC), UL 891 (Switchboard) or 1558 (Switchgear), depends on what you bought or specified.

Thanks for the reply. What would be the differences?

 

[ron]

Thanks for the reply. What would be the differences?

Each one has different construction minimums and conditions.

For example, UL 1558 can withstand a short circuit for 30 cycles at its rating, whereas 891 is 3 cycles. Plus many many more differences

 

[Jraef]

History lesson: The original "Motor Control Center" was the Westinghouse 1100 Series released in 1956, as a "specialized" version of their 1100 Series Switchboards, modified to hold motor starters in individual compartments that could be plugged in and out of the bus.

If it's a main for an MCC, connecting directly to the MCC bus, it's usually UL845, but really, there is virtually no difference between UL891 and 845 when it comes to a single breaker in a section like that. So for people that make both MCCs and Switchboards, it could go either way; most of them will offer it as an option, especially if you need a SUSE label and metering section on it (in which case it will probably be 891). For those like Allen Bradley that only make MCCs, it will be UL845 listed.

If you are going to connect to the MCC via cable, a Switchboard format would probably cost less for the breaker, but then you would need to add a 2500A MLO to the MCC lineup so altogether it would cost you more.

 

[Electriman]

History lesson: The original "Motor Control Center" was the Westinghouse 1100 Series released in 1956, as a "specialized" version of their 1100 Series Switchboards, modified to hold motor starters in individual compartments that could be plugged in and out of the bus.

If it's a main for an MCC, connecting directly to the MCC bus, it's usually UL845, but really, there is virtually no difference between UL891 and 845 when it comes to a single breaker in a section like that. So for people that make both MCCs and Switchboards, it could go either way; most of them will offer it as an option, especially if you need a SUSE label and metering section on it (in which case it will probably be 891). For those like Allen Bradley that only make MCCs, it will be UL845 listed.

If you are going to connect to the MCC via cable, a Switchboard format would probably cost less for the breaker, but then you would need to add a 2500A MLO to the MCC lineup so altogether it would cost you more.

Thanks for the insightful reply. Is there anyway to find out whether a 2500 A breaker section is a switchgear or MCC simply by just looking at it?

 

[Jraef]

Thanks for the insightful reply. Is there anyway to find out whether a 2500 A breaker section is a switchgear or MCC simply by just looking at it?

The label on the front that says "Motor Control Center" would be a dead giveaway, but other than that, not absolutely.

In a lot of cases a Switchboard will just have the breaker toggle handle sticking out of the front.

In an MCC, that's usually going to have a separate disconnect mechanism operated with the door closed and you don't see the actual breaker handle on the outside.