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 Post subject: Labeling MCC's with Main
PostPosted: Tue Jun 16, 2009 7:49 am 
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Joined: Mon Nov 10, 2008 1:08 pm
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Location: Cincinnat, OH
I have been searching for some clarification to see what industry is doing on this and reading backlog threads on the site but have not found anything that specifically addresses this. If an MCC has a main breaker is there two different IE values associated with that equipment? Let me explain a little better.... for switchgear and switchboards that have a main that is separate from the feeder breakers we calculate and label for line side of the main breaker if you are to "work" on or in the main breaker compartment. If you are to work on the feeder breaker compartments which are protected my the main we label a different value to lower the level of protection needed. We are comfortable with that approach but have questions whether the same practice is applicable for an MCC with a main.

So after that... my question is how are other people handling this situation with MCC's with a main? One label that covers the entire gear, or a label for line side of main and one for load side?


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PostPosted: Tue Jun 16, 2009 1:12 pm 
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Location: North Florida
I'm doing it the same. The secondary main breaker compartment of the PDC gets the label for the incoming side of the breaker - often an HC4 on our 600V systems. The balance of the PDC gets labeled for the secondary side of the main/primary side of feeder breakers - typically HC2. This way the equipment is labeled for the highest level of exposure when performing work.

Most of my MCCs don't have mains in them so I just label for the rating to the MCC. But if I did have mains, the main compartment would be labeled for the incoming exposure. The balance of the MCC would be labeled for the secondary side of the main so you would have two stickers. That then becomes a training issue for your personnel and any contractors doing electrical work in your facility to understand the two label system.

TxEngr


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PostPosted: Wed Jan 13, 2010 11:43 am 

Joined: Tue Nov 03, 2009 12:34 pm
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Location: New Jersey
We have taken the approach to identify the complete motor control center with the high category which usually the main compartment. Our reasoning is the purpose of labeling is for safety. I have tried to get a answer from different manufactures, company's that do arc flash studies, and different web sites and the answer are always different. I spoke with Square D represenatives and their answer was use the highest rating, An arc flash study group spoke with Allen Bradley and they say you can use different labels on main and other sections. Ask youself this if you had to put your face in a compartment what would you wear. Training people to make sure they read the right label doesn't always work use one label and there can be no mistake.


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PostPosted: Wed Jan 13, 2010 11:56 am 
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Joined: Thu Jul 19, 2007 7:54 am
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Location: St. Louis, MO
We also label the main separately, provided it is in a separate section or compartment. If it is in a column with other breakers, the entire column gets the same label.

I have heard the opinion lately, though, that you should not do this for MCC's, or even most switchgear. The thought is that unless the switchgear is fully arc rated, you cannot assume that a fault in the main compartment will not propogate to the rest of the MCC or switchgear. I don't think I agree with it, and think it is a little excessive. I could see the case being made that it should be so for a couple of columns over, however.
Has anyone else heard this?


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PostPosted: Wed Jan 13, 2010 12:56 pm 
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Location: Lawrenceburg KY
Again WDN we think the same.

IMO, the labeling method is dependent on the type of equipment and who is doing the labeling (in-house or contract). Just remember, multi-labels can or may create worker confusion. We all know that it takes more then a label to prevent accidents so training and knowledge of how the equipment is labeled and its hazards will help prevent any confusion. And we all know how many times proper training does not come about.

IMO, I would look at how a court would portray a panel with all these labels on it: “DANGER High Voltage”, “Danger 480V”, “NOTICE 3FT Clearance”, “Manufacture labels”, “Equipment ID”, “Warning Arc Flash Hazard, HRC/PPE Labels”, all these labels all over the panels.

A large picture of this panel with burn marks and all the labels being circled in red ink is setup in a courtroom.
Your Honor, My client was placed in harms way and became confused from all the labels and read HRC0. Yes he was working on the HRC4 consisting of higher hazards when the accident occurred as there is very little doubt of this because of the extent of his injuries. My client looked at all the labels and was pressured by management to get the equipment going quickly. My client seeing all these labels became confused and figuring it was a labeling mistake, as my client was never trained or informed after the labels were applied, he went with the HRC0 PPE because that's what he was wearing. The label and PPE matched and he had to fix the problem and quick because his boss MR. JONES said it had to be fixed in 10 minutes or they would find someone else to replace my client. Heck, it would take 10 minutes for my client to get to the HRC4 gear. The debat goes on and on. Does any engineering or consultant want to go through that in court?

You have to step back and say well an engineering firm would not want to go to court and have to explain this? So the contractor does the one label method per MCC. But the end user or a company doing their own study may be able to get by with more labels per MCC sections -Line/load side labeling. Since most likely the company would be in court anyways.


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PostPosted: Wed Mar 12, 2014 4:13 pm 

Joined: Mon Jun 30, 2008 12:07 pm
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Location: Charlotte, NC
It's been awhile since this question was asked. Any updates since 2010? Which of the following are you doing?
1. One label for the entire MCC. If so, where do you put it?
2. Two labels: one for the main and one for the rest of the MCC
3. Separate labels for each bucket


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PostPosted: Thu Mar 13, 2014 5:08 am 
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Location: Port Huron, Michigan
Using one designation for the entire MCC (based on the bus bars) and placing labels every two or three vertical sections.


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 Post subject: Re:
PostPosted: Tue Jul 21, 2015 5:40 pm 
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Joined: Fri Jan 11, 2008 4:35 pm
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zrjohnso wrote:
It's been awhile since this question was asked. Any updates since 2010? Which of the following are you doing?
1. One label for the entire MCC. If so, where do you put it?
2. Two labels: one for the main and one for the rest of the MCC
3. Separate labels for each bucket


We have been supplying two (Lineside MCB/Loadside MCB+BUS) as well as an additional marking and Label if Arc Flash Reduction Switch (ARMS) is installed on the MCB (ARMS ON/ARMS OFF)


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