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Removing bucket from AB MCC and replacing with disconnect switch

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Customer would like to pull a 200a power feed from this MCC. Older Allen bradley unit.

There is an existing large bucket on the top right that is currently not being used. it looks like it is bolted to the MCC enclosure and there is a chase nipple for the feed. Wiring presumably terminates on lugs inside the MCC on busbar

Customer suggested removing the bucket, installing a 200a fused disconnect in its place, or installing the disconnect on the side of the MCC nippled in.

This is a little shoemaker IMO and I'd like to hear what you guys think of this.

There are knockouts on the side of the MCC where i could theoretically bolt the new disconnect on and nipple in.

Either way i will be doing a power log on the feed to the MCC to see if i even have 200a of capacity left.

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Discussion Starter · #6 ·
There might be a good reason it is tagged DO NOT USE, I would suggest that you look into the bus connection first and see why the tag is there...And power the board down before you go looking for a surprise.
i would need to pull new wiring into it either way.

I will be putting a power logger on the bus so i will inspect it at that point


im wondering how kosher it would be to re-use the bucket enclosure, installing a 200a breaker inside.
 

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or is bucket damaged...hence the DO NOT USE piece of tape.
That looks like the pump is out of service and they left the wires there for “Future” use.

That’s the bucket I would use if the glycol pump is never being used again. Pull that run out.
 

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im wondering how kosher it would be to re-use the bucket enclosure, installing a 200a breaker inside.
We do it all the time. but we insure that the breaker can be operated with the door closed.
 

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What size is the bucket disconnect, should be labeled on the side of it. If it were big enough, I would get the factory trailing fuse block kit. If it's only a 100A switch, I think your into tapping the bus, for something adequate. The bus taps to the existing switch may not be large enough.
 

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Discussion Starter · #10 ·
What size is the bucket disconnect, should be labeled on the side of it. If it were big enough, I would get the factory trailing fuse block kit. If it's only a 100A switch, I think your into tapping the bus, for something adequate. The bus taps to the existing switch may not be large enough.
considering the size of it, it was surprisingly only rated for 30 or 40a inside on the little nameplate
 

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considering the size of it, it was surprisingly only rated for 30 or 40a inside on the little nameplate
Some buckets that size had more than one contactor inside them. Maybe wye/delta setup for that pump?
 

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I have seen the tap rule applied and come off of the buss bars with a fused disconnect, it don't look like they are going to expand it.
That said I don't think I would add anything large to that old thing.

Cowboy
 

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I did some basic checking on that Size 2 part number. It was a two speed size 2 combination starter. In these size applications they typically came with a 60 or sometimes 100A disconnect switch and a trailing fuse block with 60 or100A fuse holders.

To get a 200A disconnect, you would need a size 4 bucket. So you will need to tap the bus and provide your own fused disconnect or breaker.

Here is a CUT SHEET for the current combination starter and sizing for your comparison.
 

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Just contact an aftermarket company like Southland in Burlington, NC. Get a bucket that works as-is.

If there is no such thing remove the splice plate cover. The bus is already punched with holes so you can just attach lugs there. Cut a hole in the cover and attach an LB and put your disconnect down at a convenient level or wherever you want to go to. This lets you access the full horizontal bus capacity.

If you call AB to buy new here is a little trick. Buy an MLO section and a section with the bucket you want plus fill it up with anything else you want. This will be MUCH cheaper. MCC buckets from the manufacturer are 300-500% higher priced when you buy just buckets. If you order a main breaker or main lugs then you get the “new MCC” price. On one smaller bucket it’s not worth it but on bigger ones or say two size 3s you save money.
 

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keep in mind that the size of the stabs on the back of the bucket will be rated for what the bucket is rated for
if you put a 200A breaker in a 60A bucket with 60A stabs to the buss you will have trouble

as paul said go directly to the buss with bolt on lugs

as you said make sure the capacity is available on the buss and particularly the feeder to the MCC
 

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Discussion Starter · #18 ·
keep in mind that the size of the stabs on the back of the bucket will be rated for what the bucket is rated for
if you put a 200A breaker in a 60A bucket with 60A stabs to the buss you will have trouble

as paul said go directly to the buss with bolt on lugs

as you said make sure the capacity is available on the buss and particularly the feeder to the MCC
In terms of calling it bucket, thats probably a mis-speak. It doesn't plug on to the bus on this MCC. Each seperate motor controller has a nipple into the back MCC enclosure and the disconnect is connected with wires. Unfortunately I didnt take a larger picture of the insides.

I think instead of trying to retrofit anything, I will quote to install a 200a fuses disconnect off of it.


appreciate all of the responses, I have not worked with these old MCCs much.
 
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