Is it an MCC or not ?

Status
Not open for further replies.
ibew441dc

ibew441dc

Senior Member
I have a disconnect , mag-starter , ct's , relays , etc. installed inside of a cabinet or cut-out box , Is this piece of equipment a motor control center ?

I say yes, some of my peers say no. The arguement started at work in reguards to 110.26(E).(Does it apply or not)

I'm sure many that are on the forum have had similar discussions. Any feedback would be great.

Thanks Ibew441dc
 
MCC...DEF... NEC....An assembly of one or more enclosed sections having a common power bus and principally containing motor control units.....Sounds like Yes.
 
iwire said:
It does not sound like an MCC to me.

It is missing the common bus.
Click to expand...


Ok, now you have me thinking:-? :-?

What is the definition of a common bus? This is easy for me in reguads to the large units but.......?
 
To me that would be a enclosure or group of enclosures with one set
of line lugs suppling two or more motor starters, or buckets as we
normally call them.

This one is obviously a large one but IMO it could be just one vertical
section with at least two buckets in order for it to have a common buss.

cogen05c.jpg
 
Iwire,

If I added a circuit breaker to my original scenario would you say that it could be a MCC as defined by article 100 def.

Inside of a cabinet I have a circuit breaker(common bus), disconnect, relays ,ct's etc. now would you say that it might be a MCC.

ibew441dc
 
Part VIII of Art 430 is Motor Control Centers
Does your MCC or what you feel is an MCC comply with the sections in Part VIII?
And take a close look at
430.98 Marking.
(A) Motor Control Centers. Motor control centers shall be marked according to 110.21.
I believe the intent is the MCC is a manufactured product, and there are Ul and NEMA standards for MCCs. What the NEC does not say is a MCC has to be listed as an MCC.
 
ibew441dc said:
Iwire,

If I added a circuit breaker to my original scenario would you say that it could be a MCC as defined by article 100 def.
Click to expand...

I think that would be a stretch.

I see it as Tom sees it, an MCC is a factory assembly.

Any that I have worked on have removable buckets that plug into a common bus.

If the equipment contained in the bucket goes bad you loosen a couple of screws, pop off a control wire terminal strip, slide the bucket out, slide in a spare and your up and running again.
 
Bob,
It looks like the MCC in the picture is fed from an ungrounded system and has a C phase ground fault. I am thinking that the lights on the right end are ground fault detection lights and it appears that 2 lamps are out and the other 4 are burning brightly. Would this be a 480 volt MCC where they used 3 sets of 240 volt lamps in series for the groung fault detection?
Don
 
Not all motor control centers have vertical sections and plug-in units. I think there should be multiple combination starters involved. I would have a hard time calling a single "back plate" custom wired enclosure an MCC.

This is from Crouse Hinds page 40.

809523f4.gif
 
Last edited:
Tom and Iwire,

thanks for the feedback

Tomorrow I will check this piece of equipment to see what it is listed as.

Just off hand do either of you know what a combo-starter , vfd , or similar motor controllers would be listed as?

Until now I thought all of these fell under 110.26(f)


ibew441dc
 
jim dungar said:
I would have a hard time calling a single "back plate" custom wired enclosure an MCC.

The original piece of equipment I was describing is not a custom wired enclosure. It is a controller made by danfous for large air handlers.

ibew441dc
Click to expand...
 
ibew441dc said:
jim dungar said:
I would have a hard time calling a single "back plate" custom wired enclosure an MCC.

The original piece of equipment I was describing is not a custom wired enclosure. It is a controller made by danfous for large air handlers.

ibew441dc
Click to expand...

Personal preference Alert - If it has a single back plate then I would call it a motor control cabinet or a motor controller not a motor control center.

Listing of equipment (i.e. UL508A for control panels) has nothing at all to do with NEC articles.
Click to expand...
 
ibew441dc said:
I have a disconnect , mag-starter , ct's , relays , etc. installed inside of a cabinet or cut-out box , Is this piece of equipment a motor control center ?

I say yes, some of my peers say no. The arguement started at work in reguards to 110.26(f).(Does it apply or not)

I'm sure many that are on the forum have had similar discussions. Any feedback would be great.

Thanks Ibew441dc
Click to expand...


Duh! What I have discribed is absolutly not a motor control center:rolleyes:

All this self imposed confusion:confused:

This equipment is an industrial control panel.

I made a common mistake of focusing on the wrong sections for the wrong answers. Thankfully this forum is here and I am able to get feedback that gets my brain working.


ibew441dc
 
Status
Not open for further replies.
Top