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 Post subject: Labeling Utilization Equipment
PostPosted: Wed Oct 07, 2009 5:52 am 
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Joined: Mon Nov 10, 2008 1:08 pm
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Location: Cincinnat, OH
I hope this is not a repeat. I spent some time digging through old threads and did not find what I was looking for. We have been having some internal discussions about labeling utilization equipment.....ie.... motor operated valve, unit heater..... our thought is that someone could potentially trouble shoot energized to find the problem. Is anyone else having this dilemma? Is anyone else labeling utilizations equipment? Is there a standard or reason not to?

Any help is appreciated.


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PostPosted: Wed Oct 07, 2009 6:27 am 
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Location: St. Louis, MO
Generally speaking, I don't label the utilization equipment, although a lot of it depends on the size and location of the enclosure.
You will not normally see very high values for the arc flash energy at the equipment, although this depends on the equipment and it's power requirements.

If it has a control cabinet that could be opened to troubleshoot, or be worked on, then I will. For most MOV's and other motors, I will label the closest disconnect. Our electricians have also been trained that the value posted on the upstream disconnect is valid for the equipment unless otherwise noted.


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PostPosted: Tue Jan 19, 2010 6:58 am 
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That is good information and I agree with that but I am wondering if there is some more concrete reason not too. I understand about not labeling them if they are a HRC of 0 but the question becomes do we have to model them and analyze to be "sure" that they are going to be a HRC 0.

How much does the NEC article 110.16 play a part in what equipment needs to be analyzed and labeled? Is it too general to be used as a guide?


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PostPosted: Tue Jan 19, 2010 9:11 am 
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This came to my thoughts the other day as well when I was asked about labeling small dry type transformers.

110.16 says equipment that "are likely to require examinatin, adjustment, servicing, or maintenance while energized shall be field marked..."

I don't think that small transformers or small motors will likely be opened while energized, and see no reason to label them individually.


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